Plus One Botany Notes Chapter 7 Transport in Plants

Students can Download Chapter 6 Cell Cycle and Cell Division Notes, Plus One Botany Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Botany Notes Chapter 7 Transport in Plants

Translocation:
It is the transport over longer distances takesplace through the vascular system (the xylem and the phloem)

Means of transport:
Diffusion:

  • It is passive process takes place from the regions of higher concentration to regions of lower
  • Diffusion is a slow process and is not dependent on a ‘living system’, it mainly occurs in gases and liquids.
  • Diffusion is very important to plants for gaseous movement within the plant body.

Plus One Botany Notes Chapter 7 Transport in Plants

Rate of diffusion:
Factors influencing diffusion are

  1. Gradient of concentration
  2. The permeability of the membrane separating them
  3. Temperature and pressure.

Facilitated Diffusion:
Substances that have a hydrophilic moiety difficult to pass through the membrane, their movement to be facilitated by protein.
Plus One Botany Notes Chapter 7 Transport in Plants 1
What is the requirement for facilitated diffusion?

  • Special membrane proteins help the movement of substances across membranes
  • Movement of substance takes place without the expenditure of ATP or energy.

Rate of facilitated diffusion:
The diffusion rate depends on the

  1. size of the substances.
  2. solubility in lipids

Features:

  1. Substances soluble in lipids diffuse through the membrane faster.
  2. It is specific and allows the cell to select substances for uptake.
  3. It is sensitive to inhibitors which react with protein side chains.
  4. Transport rate reaches a maximum when all of the protein transporters are being used (saturation).
  5. The proteins form channels in the membrane. Some channels are always open others can be controlled

Nature of transport protein:
1. The porins are proteins that form huge pores in the outer membranes of the plastids, mitochondria and some bacteria that allowing molecules up to the size of small proteins to pass through.

2. Some of the transport protein rotates and releases the molecule inside the cell, eg: water channels – made up of eight different types of aquaporins.

Plus One Botany Notes Chapter 7 Transport in Plants 2

Plus One Botany Notes Chapter 7 Transport in Plants

Passive symports, antiports and uniport:

  1. In a symport, both molecules cross the membrane in the same direction with help of carrier or transport proteins.
  2. In an antiport, they move in opposite directions.
  3. When a molecule moves across a membrane independent of other molecules, the process is called uniport.

Active Transport:
Active transport is a uphill process why?

  • Proteins transport substances from a low concentration to a high concentration (‘uphill’ transport) by using energy
  • It is carried out by membrane-proteins.
  • Transport rate reaches a maximum when all the protein transporters are being used or are saturated.
  • This carrier protein is very specific in transport and sensitive to inhibitors that react with protein side chains.

Comparison of Different Transport Processes:

  • Proteins in the membrane show common characteristics of being highly selective; they are liable to saturate, respond to inhibitors and are under hormonal regulation.
  • But diffusion whether facilitated or not take place only along a gradient and do not use energy.

Plus One Botany Notes Chapter 7 Transport in Plants 3

Plant- Water relations:

  • Water is the medium in which most substances are dissolved.
  • The protoplasm of the cell contains water in which different molecules are dissolved and suspended.
  • A watermelon has over 92 percent water; most herbaceous plants have only about 10 to 15 percent of its fresh weight as dry matter.
  • Terrestrial plants take up huge amount water daily but most of it is lost to the air through evaporation from the leaves, i.e., transpiration.
  • A mature corn plant absorbs almost three litres of water in a day, while a mustard plant absorbs water equal to its own weight in about 5 hours.
  • Water is the limiting factor for plant growth and productivity.

Plus One Botany Notes Chapter 7 Transport in Plants

Water Potential:

  • It is the sum of Solute potential and pressure potential.
    • \(\Psi_{w}=\Psi_{x}+\Psi_{p}\)
  • Water potential is denoted by the Greek symbol Psi.
  • It is expressed in pressure units such as pascals (Pa).

Solution have a lower water potential than pure water why?
When solute dissolves water potential is decreased called solute potential (negative sign)

  • Water molecules possess kinetic energy. The greater the concentration of water in a system, the greater is its kinetic energy or ‘water potential’.
  • Water move from the higher water potential to the lower water potential.

How can increase water potential?

  • If a pressure greater than atmospheric pressure is applied to pure water or a solution, its water potential increases
  • Water enters a plant cell due to diffusion causing a pressure built up against the cell wall, it makes the cell turgid, this increases the pressure potential. (sign is positive)
  • Water potential of a cell is affected by both solute and pressure potential.
For a solution at atmospheric pressure (water potential) = (solute potential)
Pure water have the greatest water potential. It is taken as zero.

Osmosis:
It is the diffusion of water across the semi-permeable membrane.
Rate of osmosis: It is influenced by

  • pressure gradient
  • concentration gradient.

1. In plant cells, the cell membrane the membrane of the vacuole (tonoplast) are together determines the movement of molecules in or out of the cell.

2. Water flows from its region of higher chemical potential (or concentration) to its region of lower chemical potential until equilibrium is reached.

3. At equilibrium the two chambers should have the same water potential.
Plus One Botany Notes Chapter 7 Transport in Plants 4

Plus One Botany Notes Chapter 7 Transport in Plants

Experiment to demonstrate osmosis:
1. In potato osmometer experiment, the tuber is placed in water the cavity in the potato tuber containing a concentrated solution of sugar collects water due to osmosis.

2. In thistle funnel experiment, sucrose solution in a funnel is separated from pure water in a beaker through a semi-permeable membrane .After some time water will move into the funnel resulting in rise in the level of the solution in the funnel. This will continue till the equilibrium is reached.

Reverse osmosis:
If an external pressure is applied from the upper part of the funnel, no water diffuses into the funnel through the membrane.
1. This pressure required to prevent water from diffusing is the osmotic pressure and this is the function of the solute concentration.

2. If increasing the solute concentration, the greater pressure is required to prevent water from diffusing in. Osmotic pressure is the positive pressure applied, while osmotic potential is negative.

3. A demonstration of osmosis. A thistle funnel is filled with sucrose solution and kept inverted in a beaker containing water, (a) Water will diffuse across the membrane (as shown by arrows) to raise the level of the solution in the funnel (b) Pressure can be applied as shown to stop the water movement into the funnel.
Plus One Botany Notes Chapter 7 Transport in Plants 5

Plasmolysis:
Importance of hypertonic solution:
When a cell is placed in a hypertonic solution water moves out due exosmosis, it causes the protoplast to shrink away from the walls. This is called plasmolysis. The cell become flaccid in state. The process of plamolysis is usually reversible.
Plus One Botany Notes Chapter 7 Transport in Plants 6

Cells become turgid state in pure water?
When the cells are placed in a hypotonic solution (higher water potential or dilute solution as compared to the cytoplasm), water diffuses into the cell due to endosmosis causing the cytoplasm to build up a pressure against the wall, that is called turgor pressure.

Isotonic solution:
If the external solution balances the osmotic pressure of the cytoplasm,it is said to be isotonic. When the cell (or tissue) is placed in an isotonic solution, there is no net flow of water towards the inside or outside. If the external solution is more dilute than the cytoplasm, it is hypotonic, cells swell in hypotonic solutions and shrink in hypertonic ones.

Plus One Botany Notes Chapter 7 Transport in Plants

Imbibition:
Imbibition is a special type of diffusion when water is absorbed by hydrophilic colloids and increase in volume.
Examples of imbibition:

  1. Absorption of water by seeds and dry wood
  2. Emerging out of seedlings from the soil

Water potential gradient between the absorbent and the liquid imbibed is essential for imbibition.

Long distance transport of water:

  • Mass flow is the movement of substances in bulk or en masse from one point to another as a result of pressure differences between the two points.
  • The bulk movement of substances through the conducting or vascular tissues of plants is called translocation.
  • Xylem is associated with translocation of water, mineral salts, some organic nitrogen and hormones, from roots to the aerial parts of the plants.
  • Phloem translocates organic and inorganic solutes, mainly from the leaves to other parts of the plants.

How do Plants Absorb Water?
Water is absorbed along with mineral solutes move deeper into root layers by two distinct pathways.
1. Apoplast pathway:

  • The apoplastic movement of water occurs exclusively through the intercellular spaces and the walls of the cells except at the casparian strips of the endodermis in the roots.
  • The apoplast does not provide any barrier to water movement and water movement is through mass flow i.e tension develop in the continuous stream of water in the apoplast due to the adhesive and cohesive properties of water

Plus One Botany Notes Chapter 7 Transport in Plants 7

2. Symplast pathway:

  • In symplastic movement the water travels through the cytoplasm of the cells
  • This intercellular movement takes place through the plasmodesmata. ‘Symplastic movement is aided by cytoplasmic streaming.
  • eg: cytoplasmic streaming in cells of the Hydrilla leaf; the movement of chloroplast due to streaming is easily visible.

Plus One Botany Notes Chapter 7 Transport in Plants 8

Plus One Botany Notes Chapter 7 Transport in Plants

Apoplastic pathway is not always continuous through cell wall why?
Apoplastic pathway is continuous upto the inner boundary of the cortex, the endodermis, is impervious,to water because of a band of suberised matrix called the casparian strip.

The water then moves through the symplast and again crosses a membrane to reach the cells of the xylem. This is the only way water and other solutes can enter the vascular cylinder.

Additional structures in water and mineral absorption:
1. A mycorrhiza is a symbiotic association of a fungus with a root system. The hyphae have a very large surface area that absorb mineral ions and water from the soil. The fungus provides minerals and water to the roots, in turn the roots provide sugars and N-containing compounds to the mycorrhizae.

2. Some plants have an obligate association with the mycorrhizae. For example, Pinus seeds cannot germinate and establish without the presence of mycorrhizae.

Water Movement up a Plant:
Root Pressure:

  • As various ions from the soil are actively transported into the vascular tissues of the roots, water flows (its potential gradient) and increases the pressure inside the xylem.
  • This positive pressure is called root pressure.
  • It helps to pushing up water to small heights.

Experiment to demonstrate root pressure:
When a small soft-stemmed plant is taken and cut the stem horizontally near the base with a sharp blade, early in the morning ,the drops of solution ooze out of the cut stem; this occurs due to positive root pressure.

When root pressure is high in herbaceous plants?
Effects of root pressure is also observable at night and early morning when evaporation is low, and excess water collects in the form of droplets around special openings of veins near the tip of grass blades, and leaves of many herbaceous parts.

Such water loss in its liquid phase is known as guttation. Root pressure do not play a major role in water movement up tall trees but it occurs in most plants by transpiratory pull

Transpiration pull:

  • Water is mainly ‘pulled’ through the plant with help of driving force – transpiration from the leaves referred to as the cohesion – tension – transpiration pull model of water transport.
  • Less than 1 percent of the water reaching the leaves is used in photosynthesis and plant growth.
  • Most of it is lost through the stomata in the leaves. This water loss is known as transpiration.

Plus One Botany Notes Chapter 7 Transport in Plants

Transpiration:
Transpiration is the evaporative loss of water occurs mainly through the stomata in the leaves.

  • Normally stomata are open in the day time and close during the night.
  • The opening or closing of the stomata is due to change in the turgidity of the guard cells.
  • The inner wall of each guard cell is thick and elastic.
  • When turgidity increases within the two guard cells the thin outer walls bulge out and opens the stoma. This is also aided due to the orientation of the microfibrils in the cell walls of the guard cells.
  • When the guard cells lose turgor, due to water loss (or water stress) the guard cells become flaccid and the stoma closes.

Plus One Botany Notes Chapter 7 Transport in Plants 9
Distribution of stomata in leaf:

  • The dorsiventral (often dicotyledonous) leaf has a greater number of stomata in the lower surface
  • Isobilateral (often monocotyledonous) leaf they are equally distributed on both surfaces.

Factors influencing transpiration:
External factors:
Temperature, light, humidity, wind speed

Plant factors:
Number and distribution of stomata, number of stomata open, per cent, water status of the plant, canopy structure, etc.

The transpiration driven ascent of xylem sap depends mainly on the following physical properties of water:

1. Cohesion: mutual attraction between water molecules.
2. Adhesion: attraction of water molecules to polar surfaces (such as the surface of tracheary elements).
3. Surface Tension: water molecules are attracted to each other in the liquid phase more than to water in the gas phase.
  • These properties give water high tensile strength, i.e., an ability to resist a pulling force, and high capillarity, i.e., the ability to rise in thin tubes.
  • In plants capillarity is aided by the small diameter of the tracheary elements – the tracheids and vessel elements
  • As water evaporates through the stomata results in pulling of water molecule by molecule, into the leaf from the xylem.
  • This occurs due to lower concentration of water vapour in the atmosphere as compared to the substomatal cavity and intercellular spaces, water diffuses into the surrounding air. This creates a ‘puli’.

Plus One Botany Notes Chapter 7 Transport in Plants 10

Plus One Botany Notes Chapter 7 Transport in Plants

Transpiration and Photosynthesis – a Compromise:
Advantageous of transpiration:

  1. creates transpiration pull for absorption and transport of plants
  2. supplies water for photosynthesis
  3. transports minerals from the soil to all parts of the plant
  4. cools leaf surfaces, sometimes 10 to 15 degrees, by evaporative cooling
  5. maintains the shape and structure of the plants by keeping cells turgid
  6. When water depleted by transpiration, photosynthesis is limited.
  7. The evolution of the C4 photosynthetic system maximising the availability of CO2 while minimising water loss.
  8. C4 plants are twice as efficient as C3 plants in terms of fixing carbon (making sugar). C4 plant loses only half as much water as a C3 plant for the same amount of CO2 fixed.

Uptake and transport of mineral nutrients: The nutritional requirements are obtained from minerals in the soil.
Uptake of Mineral Ions:
All minerals cannot be passively absorbed by the roots because

(i) minerals are present in the soil as charged particles (ions) which cannot move across cell membranes.
(ii) the concentration of minerals in the soil is usually lower than the concentration of minerals in the root. Therefore, most minerals must enter the root by active absorption. This needs energy in the form of ATP
  • The active uptake of ions is partly responsible for the water potential gradient in roots, and therefore for the uptake of water by osmosis.
  • Specific proteins in the membranes of root hair cells actively pump ions from the soil into the cytoplasm of the epidermal cells.
  • Root endodermis because of the layer of suberin has the ability to actively transport ions in one direction only.

Translocation of Mineral Ions:
Chiefsinks:

  1. Apical and lateral meristems
  2. young leaves
  3. developing flowers
  4. fruits and seeds
  5. the storage organs

Unloading of mineral ions occurs at the fine vein endings through diffusion and active uptake by these cells.

Mineral ions are frequently remobilized from older senescing parts to younger leaves. Some decidous plants, before leaf fall minerals are removed to other parts Mobilising elements are phosphorus, sulphur, nitrogen and potassium.
  • Some elements that are structural components like calcium are not remobilised.
  • An analysis of the xylem exudates shows that though more amount of nitrogen carried in the organic form as amino acids small amounts of P and S are carried as organic compounds.
  • Small amount of exchange of materials does take place between xylem and phloem.

Plus One Botany Notes Chapter 7 Transport in Plants

Phloem transport: flow from source to sink:
Phloem transport is bidirectional but xylom transport is unidirectional why?
Source is the part of the plant which synthesises the food. Sink is the part that needs or stores the food. Food ( sucrose) is transported by phloem from a source to a sink.lt is the downward transport Sugar stored in roots are mobilized to the buds of trees during early spring and act as sink.

This is called upward transport .Hence phloem transport is bi-directional. Phloem sap is mainly water and sucrose, but other sugars, hormones and amino acids are also transported or translocated through phloem. Xylem transport is always unidirectional, i.e. upwards.

The Pressure Flow or Mass Flow Hypothesis:
The accepted mechanism used for the translocation of sugars from source to sink is called the pressure flow hypothesis.
What is the loading of phloem?
The sugar is moved in the form of sucrose(a disaccharide) into the companion cells and then Tlpo!stem. into the living phloem sieve tube cells by active transport. This process is called loading. It produces a hypertonic condition in the phloem.

  • Phloem tissue is composed of sieve tube cells, which form long columns with holes in their end walls called sieve plates. ‘Cytoplasmic strands pass through the holes in the sieve plates,
  • Water in the adjacent xylem moves into the phloem by osmosis.
  • As hydrostatic pressure( Osmotic pressure) builds up in the in the phloem sieve tube, pressure flow begins and phloem sap move to areas of lower pressure
  • Active transport is necessary to move the sucrose out of the phloem sap and sugars are removed, the osmotic pressure decreases and water moves out of the phloem.
  • The loss of solute produces a high water potential in the phloem, and water passes out to xylem.

Plus One Botany Notes Chapter 7 Transport in Plants 11

Plus One Botany Notes Chapter 7 Transport in Plants

Girdling experiment:
It is used to identify the tissues through which food is transported. On the trunk of a tree a ring of bark up to a depth of the phloem layer is removed. In the absence of downward movement of food ,the portion of the bark above the ring on the stem becomes swollen after a few weeks.

This simple experiment shows that phloem is the tissue responsible for translocation of food and transport takes place in one direction, i.e., towards the roots.

Plus One Botany Notes Chapter 6 Cell Cycle and Cell Division

Students can Download Chapter 6 Cell Cycle and Cell Division Notes, Plus One Botany Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Botany Notes Chapter 6 Cell Cycle and Cell Division

Cell cycle:
It involves

  1. Cell division
  2. DNA replication
  3. Cell growth

these all process take place in a coordinated way. The replicated chromosomes (DNA) are then distributed to daughter nuclei.

Plus One Botany Notes Chapter 6 Cell Cycle and Cell Division

Phases of Cell Cycle:
Time taken for division:
The duration of cell cycle vary from organism to organism and also from cell type to cell type

  • In typical eukaryotic cell cycle (human cells in culture) cells divide once in every 24 hours
  • Yeast cell divide in every 90 minutes.

The cell cycle and two basic phases:

  • Interphase
  • M Phase (Mitosis phase)

Interphase:
The interphase lasts more than 95% of the duration of cell cycle. It is divided into three phases.
1. G1 phase (Gap 1):
G phase is the interval between mitosis and initiation of DNA replication. In this phase cell is metabolically active and continuously grows.

2. S phase (Synthesis):
It is the period which DNA synthesis or replication takes place.

What happens to DNA after S phase?
During S phase amount of DNA per cell doubles. If the initial amount of DNA is denoted as 2C then it Increases to 4C. But the chromosome number is not changed

Events in nucleus and cytoplasm:
In animal cells, during the S phase, DNA replication begins nucleus, and the centriole duplicates in the cytoplasm.

3. G2 phase (Gap 2):
During the G2 phase, proteins are synthesised in preparation for mitosis while cell growth continues.
Plus One Botany Notes Chapter 6 Cell Cycle and Cell Division 1

M Phase (Mitosis phase):

  • M Phase represents actual cell division or mitosis
  • The M Phase starts with the nuclear division and the separation of daughter chromosomes (karyokinesis).
  • It ends with division of cytoplasm (cytokinesis).

Quiescent stage (Go)L
Some cells in the adult animals do not exhibit division (e.g, heart cells), exit G1 phase to enter an inactive stage called quiescent stage.

Common features:
Cells in this stage remain metabolically active but no longer proliferate .But proliferate depending on the requirement of the organism.

Plus One Botany Notes Chapter 6 Cell Cycle and Cell Division

M Phase:
This is the most dramatic period of the cell cycle.
Mitosis is an eauational division why?
The number of chromosomes in the parent and progeny cells is the same hence* it is also called as equational division. Mitosis is divided into the following four stages:

  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase

1. Prophase:
It starts after cthe completion of G2 phase.
Key features:

  • Chromosomal material condenses to form compact mitotic chromosomes. It consists of two chromatids attached together at the centromere.
  • Initiation of the assembly of mitotic spindle fibres.
  • At the end of prophase golgi complexes, endoplasmic reticulum, nucleolus and the nuclear envelope disappears.
  • The centriole begins to move towards opposite poles of the cell.

Plus One Botany Notes Chapter 6 Cell Cycle and Cell Division 2

2. Metaphase:
The plane of alignment of the chromosomes at metaphase is referred to as the metaphase plate.
Maximum condensation of chromosome:
In this stage, condensation of chromosomes is completed and morphology of chromosomes can be easily studied. key features:

  • Spindle fibres attach to kinetochores of chromosomes.
  • Chromosomes are moved to spindle equator and get aligned along metaphase plate through spindle fibres to both poles.

Plus One Botany Notes Chapter 6 Cell Cycle and Cell Division 3

Plus One Botany Notes Chapter 6 Cell Cycle and Cell Division

3. Anaphase:
key features:

  • Centromeres split and daughter chromatids separate.
  • Chromatids move to opposite poles and centromere of each chromosome is towards the pole.

Plus One Botany Notes Chapter 6 Cell Cycle and Cell Division 4

4. Telophase
It is the final stage of mitosis, in which the chromosomes reached their respective poles
key features:

  • Chromosomes cluster at opposite spindle poles and their identity is lost as discrete elements. Chromosome decondense as chromatin material.
  • Nuclear envelope assembles around the chromosome clusters.
  • Nucleolus, golgi complex and ER reappears.

Plus One Botany Notes Chapter 6 Cell Cycle and Cell Division 5

Plus One Botany Notes Chapter 6 Cell Cycle and Cell Division

Cytokinesis:
In this two daughter cells separate by a process called cytokinesis.
Cytokinesis in animal cell:
In an animal cell, the appearance of a furrow in the plasma membrane which gradually deepens and ultimately joins in the centre, dividing the cell cytoplasm into two.

Cytokinesis in plant cell:
In plant cells, wall formation starts in the centre of the cell and grows outward to meet the lateral walls. The formation of the new cell wall begins with the formation of a simple precursor, called the cell-plate that represents the middle lamella between the walls of two adjacent cells.

How does a cell become multinucleated?
In some organisms karyokinesis is not followed by cytokinesis as a result of which multinucleate condition arises leading to the formation of syncytium (eg: liquid endosperm in coconut).

Significance of Mitosis:
Mitosis is restricted to the diploid cells only. But in some lower plants and in some social insects haploid cells also divide by mitosis.

  1. Mitosis results in the production of diploid daughter cells with identical genetic constitution.
  2. The growth of multicellular organisms is due to mitosis.
  3. Cell growth results in disturbing the ratio between the nucleus and the cytoplasm.
  4. Mitosis helps to cell repair, i.e cells of the upper layer of the epidermis, cells of the lining of the gut, and blood cells are being constantly replaced.
  5. Mitotic divisions in the meristematic tissues – the apical and the lateral cambium, result in a continuous growth of plants throughout their life.

Plus One Botany Notes Chapter 6 Cell Cycle and Cell Division

Meiosis:
The cell division that reduces the chromosome number by half results in the production of haploid daughter cells. This kind of division is called meiosis.

What is common to sexually reproducing organisms?
Meiosis ensures the production of haploid phase in the life cycle of sexually reproducing organisms whereas fertilisation restores the diploid phase.

Key features:

  1. Meiosis involves two sequential cycles of nuclear and cell division called meiosis I and meiosis II but only a single cycle of DNA replication.
  2. Meiosis I is initiated after the parental chromosomes have replicated to produce identical sister chromatids at the S phase.
  3. Meiosis involves pairing of homologous chromosomes and recombination between them.
  4. Four haploid cells are formed at the end of meiosis II.
Meiosis I Meiosis II
Prophase I Prophase II
Metaphase I Metaphase II
Anaphase I Anaphase II
Telophasel I Telophasel II

Meiosis I:
Prophase I:
Prophase is typically longer and more complex when compared to prophase of mitosis. It is subdivided into five phases based on chromosomal behaviour i.e., Leptotene, Zygotene, Pachytene, Diploteneand Diakinesis.

1. Leptotene stage:
The chromosomes become gradually visible under the light microscope. The compaction of chromosomes continues throughout leptotene.
2. Zygotene stage:
During this stage homologous chromosomes start pairing together and this process is called synapsis. Synapsis is accompanied by the formation of complex structure called synaptonemal complex. Synapsed homologous chromosome is called a bivalent or a tetrad. The first two stages of prophase I are relatively short-lived.
3. Pachytene stage:
During this stage bivalent chromosomes appears as tetrads. This stage is characterised by the appearance of recombination nodules, the sites at which crossing over (exchange of genetic material between two homologous Chromosomes) occurs between non-sister chromatids. The enzyme involved is called recombinase.
4. Diplotene stage:
During this stage dissolution of the synaptonemal complex and the tendency chromosomes of the bivalents to separate from each other except at the sites of crossovers. These X-shaped structures, are called chiasmata. In oocytes of some vertebrates, diplotene stage last for months or years
5. Diakinesis stage:
During this stage terminalisation of chiasmata occurs. The chromosomes are fully condensed and the meiotic spindle is assembled for separation of chromosomes. By the end of diakinesis, the nucleolus and the nuclear envelope disappears.

Plus One Botany Notes Chapter 6 Cell Cycle and Cell Division

Metaphase I:
The bivalent chromosomes align on the equatorial plate. The spindle fibers attach to the pair of homologous chromosomes.

Anaphase I:
The homologous chromosomes separate, while sister chromatids remain associated at their centromeres.

Telophase I:
The nuclear membrane and nucleolus reappear. After cytokinesis diad of cells are formed. The stage between the two meiotic divisions is called interkinesis. It is short lived. Interkinesis is followed by prophase II, a much simpler prophase than prophase I.
Plus One Botany Notes Chapter 6 Cell Cycle and Cell Division 6

Meiosis II:
Meiosis II resembles a normal mitosis

Prophase II:
Meiosis II begins after cytokinesis, The nuclear membrane disappears by the end of prophase II. The chromosomes again become compact.

Metaphase II:
At this stage the chromosomes align at the equator and Spindle fibers get attached to the kinetochores of sister chromatids.

Anaphase II:
It begins with splitting of the centromere of each chromosome allowing them to move toward opposite poles of the cell.

Telophase II:
Meiosis ends with telophase II, in which the two groups of chromosomes get enclosed by a nuclear envelope; cytokinesis follows resulting in the formation of tetrad of cells i.e., four haploid daughter cells.
Plus One Botany Notes Chapter 6 Cell Cycle and Cell Division 7

Plus One Botany Notes Chapter 6 Cell Cycle and Cell Division

Significance of meiosis:

1. Meiosis conserves the specific chromosome number of each species across generations in sexually reproducing organisms.
2. It results in reduction of chromosome number by half.
3. It increases the genetic variability from one generation to the next.
4. Variations are very important for the process of evolution.

Plus One Botany Notes Chapter 5 Cell The Unit of Life

Students can Download Chapter 5 Cell The Unit of Life Notes, Plus One Botany Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Botany Notes Chapter 5 Cell The Unit of Life

What is a cell?
Cell is the structural and functional unit of all living organisms. Anton Von Leeuwenhoek first saw and described a living cell Robert Brown discovered the nucleus Unicellular organisms are capable of

  • independent existence and
  • performing the essential functions of life.

Plus One Botany Notes Chapter 5 Cell The Unit of Life

Cell theory:
Schleiden and Schwann together formulated the cell theory:

  • In 1838, Malthias Schleiden, a German botanist proposed that all plants are composed of different kinds of cells.
  • In 1839 Schwannan British Zoologist, studied different types of animal cells and reported plasma membrane.

Rudolf Virchowd 855) -Contribution of modification of cell theory:
The new cells arise from pre-existing cells (Omnis cellula-e cellula)
Core elements of cell theory:

(i) All living organisms are composed of cells and products of cells.
(ii) All cells arise from pre-existing cells

An overview of cell:
Cell boundary of plant cell and animal cell:

  • The onion cell which is a typical plant cell, has a distinct cell wall and inner cell membrane.
  • The cells of the human cheek have an outer membrane as the delimiting structure of the cell.

Plus One Botany Notes Chapter 5 Cell The Unit of Life 1

Prokaryotic and eukaryotic cell body:

  • Cells that have membrane bound nuclei are called eukaryotic whereas cells that lack a membrane bound nucleus are prokaryotic.
  • In both prokaryotic and eukaryotic cells, a semi-fluid matrix forms the cytoplasm.

Membrane bound cell organelle of eukaryotes:

  1. Nucleus
  2. Endoplasmic reticulum (ER)
  3. Golgi complex
  4. Lysosomes
  5. Mitochondria
  6. Microbodies
  7. Vacuoles.

Which is the common cell organelle found in both prokaryotes and eukaryotes?
Ribosomes are non-membrane bound organelles found in both eukaryotic and prokaryotic cell.

  • Ribosomes are found not only in the cytoplasm but also within the organelles – chloroplasts and mitochondria and on rough ER.
  • Animal cells contain another non-membrane bound organelle called centriole which helps in cell division.

Cells in different measurement:

Mycoplasmas, the smallest cells, are only 0.3μm in length while bacteria is 3 to 5μm
Human red blood cells are about 7.0μm in diameter.

The largest cell is the egg of an ostrich and the longest is Nerve cells.

Plus One Botany Notes Chapter 5 Cell The Unit of Life

Prokaryotic cells:
The prokaryotic cells are represented by {bacteria, blue-green algae, mycoplasma and PPLO (Pleuro Pneumonia Like Organisms)}
Classification based on the shape:

  1. Bacillus (rod like)
  2. Coccus (spherical
  3. Vibrium (comma shaped)
  4. Spirillum (spiral)

(a) The fluid matrix found in the prokaryotic cell is the cytoplasm.

(b) There is no well-defined nucleus

Plasmids:
In addition to the genomic DNA, many bacteria have small circular DNA outside the genomic DNA. These are called plasmids .So they are organisms resistance to antibiotics. The invaginations of plasma membrane seen inside the cell is called mesosome
Plus One Botany Notes Chapter 5 Cell The Unit of Life 2

Cell Envelope and its Modifications:
Three layers of Cell boundary:

  1. Glycocalyx (Outer)
  2. The cell wall (Middle)
  3. Plasma membrane (Inner)

(a) In some bacteria, Glycocalyx is a loose sheath called the slime layer while in others it is thick and tough, called the capsule

(b) Cell wall determines the shape of the cell and provides a strong structural support to prevent the bacterium from bursting.

Mesosome:
They are the extensions of plasma membrane in the form of vesicles, tubules and lamellae.

Functions
They help in

  1. cell wall formation 1
  2. DNA replication, distribution.to daughter cells
  3. respiration
  4. secretion processes
  5. increase the surface area of the plasma membrane.

Chromatophores:
Membranous extensions in the cytoplasm which contain pigments. eg: cyanobacteria
Plus One Botany Notes Chapter 5 Cell The Unit of Life 3
Three parts of bacterial flagellum

  1. Filament
  2. Hhook
  3. Basal body.

The other important surface structures in bacteria:

  1. The pili are elongated tubular structures helps in conjugation
  2. The fimbriae are small bristle like fibres helps to attach the bacteria on rocks in streams and the host tissues.

Gram +ve and gram -ve:
Christian Gram introduced this method for classifying bacteria. Bacteria that can retain stain(crystal violet) are called Gram positive Bacteria that cannot retain stain are called Gram negative.

Plus One Botany Notes Chapter 5 Cell The Unit of Life

Ribosomes and inclusion Bodies:

  • In prokaryotes 70S prokaryotic ribosomes consists of subunits – 50S and 30S units.
  • Several ribosomes attach to a single mRNA and form a chain called polyribosomes or polysome.

Function:
The ribosomes translate the mRNA into proteins.

Inclusion bodies:

  • The examples are phosphate granules, cyanophycean granules and glycogen granules.
  • Gas vacuoles are found in blue green and purple and green photosynthetic bacteria.

Eukaryotic cells
They possess well defined and membrance bound cell organelles include

  1. protists
  2. plants
  3. animals
  4. fungi.

Cell Membrane:
Structure of membrane:

  • It consist of lipid bilayer arranged within the membrane with the polar head towards the outer sides and the hydrophobic tails towards the inner part.
  • The non polar tail of saturated hydrocarbons is protected from the aqueous environment
  • The ratio of protein and lipid varies in different cell types.
  • In human beings, the membrane of the erythrocyte has approximately 52 per cent protein and 40 per cent lipids
  • The peripheral proteins lie on the surface of membrane while the integral proteins are buried in the membrane.

Plus One Botany Notes Chapter 5 Cell The Unit of Life 4

Who proposed the well accepted model of membrane?
Singer and Nicolson (1972) proposed the fluid mosaic model.The quasi-fluid nature of lipid enables lateral movement of proteins within the bilayer.
Functions:

  1. Transport molecules without energy requirement called as passive transport
  2. Neutral solutes move across the membrane from higher concentration to the lower by the process of simple diffusion.
  3. Water move across this membrane from higher to lower concentration by diffusion is called osmosis.

Carrier protein in transport:
As the polar molecules cannot pass through the non polar lipid bilayer, they require a carrier protein to facilitate their transport across the membrane.

Carrier protein and energy in transport:
A few ions or molecules are transported across the membrane from lower to the higher concentration with the help of energy (ATP is utilized). It is called active transport eg: Na+/K+ Pump.

Plus One Botany Notes Chapter 5 Cell The Unit of Life

Cell Wall:
Function:
Cell wall gives shape and protects the cell from mechanical damage and infection. It also helps in cell-to-cell interaction and provides barrier to undesirable macromolecules.

Algal cell wall:
It consists Cellulose, galactans, mannans and minerals like calcium carbonate.

Plant cell wall:
It consists of cellulose, hemicellulose, pectins and proteins.

  • The cell wall of a young plant cell, the primary wall is capable of growth, which later disappears and secondary wall is formed on the inner (towards membrane) side of the cell
  • The middle lamella is made up of calcium pectate which holds the neighbouring cells together.
  • Cytoplasmic strands like plasmodesmata which connects cytoplasm of one cell to another through cell wall and middle lamellae.

Endomembrane System:
The endomembrane system include

  1. endoplasmic reticulum (ER)
  2. golgicomplex
  3. lysosomes
  4. vacuoles.

1. The Endoplasmic Reticulum (ER):
Salient features:

  • It is the network of tubular structures scattered in the cytoplasm
  • ER divides the intracellular space into two distinct compartments, i.e., luminal(inside ER) and extra luminal (cytoplasm)compartments.

Rough endoplasmic reticulum and Smooth endoplasmic reticulum:
The endoplasmic reticulum bearing ribosomes on their surface is called rough endoplasmic reticulum (RER). It is involved in protein synthesis and secretion.

The endoplasmic reticulum devoid of ribosome are called smooth endoplasmic reticulum (SER). It is involved in synthesis of lipids In animal cells, lipid-like steroidal hormones are synthesised
Plus One Botany Notes Chapter 5 Cell The Unit of Life 5

2. Golgi apparatus:
It was first observed Camillo Golgi (1898) as densely stained reticular structures near the nucleus.
Function:

  • Packaging of materials
  • It is the important site of formation of glycoproteins and glycolipids.

Plus One Botany Notes Chapter 5 Cell The Unit of Life

Salient features:

  • They consist of many flat, disc-shaped sacs or cisternae of 0.5 μm to 1.0 μm diameter stacked parallel to each other
  • The Golgi cisternae are concentrically arranged near the nucleus with distinct convex cis or the forming face and concave trans or the maturing face. The cis and the trans faces are interconnected.
  • Materials to be packaged in the form of vesicles from the ER fuse with the cis face of the golgi apparatus and move towards the maturing face.
  • The proteins arise from the endoplasmic reticulum are modified in the cisternae of the golgi apparatus and are released from its trans face.

Plus One Botany Notes Chapter 5 Cell The Unit of Life 6

3. Lysosomes:
Salient features:

  • * They are membrane bound vesicular structures formed by the process of packaging in the golgi apparatus.
  • The hydrolytic enzymes found in these vescicles (hydrolases – lipases, proteases, carbohydrases) are active at the acidic pH.
  • These enzymes are capable of digesting carbohydrates, proteins, lipids and nucleic acids.

4. Vacuoles:
Salient features:

  • It is the membrane-bound space found in the cytoplasm.
  • It contains water, sap, excretory product and other materials
  • In plant cells the vacuoles occupy up to 90 percent of the volume of the cell.
  • The membrane surrounding the vacuole is the tonoplast,

Function:
It facilitates the transport of ions and other materials against concentration gradients into the vacuole

Type of vacuoles in lower organisms:
In Amoeba the contractile vacuole is important for excretion. In protists, food vacuoles are formed by engulfing the food particles.

Mitochondria:
Salient features:

  1. It is the cylindrical structure having a diameter of 0.2 to 1.0μm
  2. Each mitochodrion is a double membrane bomd structure.
  3. The inner compartment is called matrix
  4. The outer membfrane forms the continous limiting boundary of the oraganelle
  5. The inner membrane forms a number of infoldings called the cristae that uncreases surface area.
  6. The matrix possess single circular DNA molecule, a few RNA molecules, and ribosomes(70s)
  7. The mitochondria divide by fission.

Function:
Mitochondria are the sites of aerobic respiration.

Plus One Botany Notes Chapter 5 Cell The Unit of Life

Power house of a cell:
They produce cellular energy in the form of ATP, hence they are called ‘power houses’ of the cell.
Plus One Botany Notes Chapter 5 Cell The Unit of Life 7

Plastids:
Plastids are found in all plant cells and in euglenoids.
Classification of plastids based on the type of pigments:
1. Chloroplasts:
The chloroplasts contain chlorophyll and carotenoid pigments which are responsible for trapping light energy essential for photosynthesis.

2. Chromoplasts:
In the chromoplasts, fat soluble carotenoid pigments like carotene and xanthophylls are present

3. Leucoplasts:
The leucoplasts are the colourless plastids of varied shapes and sizes with stored nutrients:

Classification of leucoplast:

Amyloplasts store carbohydrates (starch), eg: potato;
Elaioplasts store oils and fats
Aleuroplasts store proteins

Chloroplast:
It is found in the mesophyll cells of the leaves. These are lens-shaped,oval, spherical, discoid or even ribbon-like organelles having variable length.

Structure of chloroplast:

  • Chloroplasts are also double membrane bound.
  • The space limited by the inner membrane of the chloroplast is called the stroma.
  • The stroma contains enzymes required for the synthesis of carbohydrates and proteins.
  • It also contains small, double-stranded circular DNA molecules and ribosomes(70S).
  • A number of organised flattened membranous sacs called the thylakoids (Chlorophyll pigments seen) are present in the stroma These are arranged in stacks like the piles of coins called grana.
  • Stroma lamellae connecting the thylakoids of the different grana.

Plus One Botany Notes Chapter 5 Cell The Unit of Life 8

Plus One Botany Notes Chapter 5 Cell The Unit of Life

Ribosomes:
These are granular structures first observed under the electron microscope as dense particles by George Palade(1953).
Chemical composition:
They are composed of ribonucleic acid (RNA) and proteins

Salient features:

  • The eukaryotic ribosomes are 80S. Here ‘S’ stands for the sedimentation coefficient
  • It consists of two sub units 60S and 40S.
  • It translate coded information in mRNA into protiens

Cytoskeleton:
Salient features:
These are network of filamentous proteinaceous structures present in the cytoplasm
Function:

  1. Mechanical support
  2. Motility
  3. Maintenance of the cell shape.

Cilia and Flagella:
Salient features:

  • Cilia and flagella are hair-like outgrowths of the cell membrane..
  • Flagella are longer and responsible for cell movement.
  • Their core is called the axoneme, possesses a number of microtubules running parallel to the long axis
  • The axoneme has nine pairs of doublets of radially arranged peripheral microtubules, and a pair of centrally located microtubules.Such an arrangement is 9 + 2.

Plus One Botany Notes Chapter 5 Cell The Unit of Life 9

Plus One Botany Notes Chapter 5 Cell The Unit of Life

Centrosome and Centrioles:
Salient features:

  • Centrosome is an organelle containing two cylindrical structures called centrioles
  • Both the centrioles in a centrosome lie perpendicular to each other.
  • It has cartwheel like organisation and made up of nine peripheral triplet fibrils of tubulin.
  • The central part of the centriole is also proteinaceous and called the hub, which is connected with tubules of the peripheral triplets by radial spokes.

Function:
The centrioles form the basal body of cilia or flagella and spindle fibres (give rise to spindle apparatus during cell division in animal cells)

Nucleus:
It was first described by Robert Brown in 1831. Nucleus stained by the basic dyes was given the name chromatin by Flemming

Non nucleated plant and animal cells:

  • Erythrocytes of many mammals
  • Sieve tube cells of vascular plants

Components of nucleus:

  1. nucleoplasm
  2. chromatin
  3. nuclear matrix
  4. nucleoli.

Plus One Botany Notes Chapter 5 Cell The Unit of Life 10
Salient Features:

  • The outer membrane is continuous with endoplasmic reticulum and bears ribosomes on it.
  • These nuclear pores are the passages through which RNA and protein molecules moves.
  • The space between two membrane is called the perinuclear space(10 to 50 nm). The nuclear matrix or the nucleoplasm contains nucleolus and chromatin.
  • The nucleoli are spherical structures (site for active ribosomal RNA synthesis).
  • Larger and numerous nucleoli are present in cells actively carrying out protein synthesis.
  • During cell division chromatin condensed to form chromosomes.

Components of chromosome:

  1. DNA
  2. basic proteins(histones)
  3. non-histone proteins
  4. RNA.

Plus One Botany Notes Chapter 5 Cell The Unit of Life

Parts of chromosome:
It has primary constriction or the centromere on the sides of which disc shaped structures called kinetochores. A few chromosomes have non-staining secondary constrictions that possess knob like structure called satellite.
Plus One Botany Notes Chapter 5 Cell The Unit of Life 11

Classification of chromosome based on position of centromere:

  1. Metacentric chromosome has middle centromere forming two equal arms.
  2. Sub-metacentric chromosome has centromere nearer to one end of the chromosome so it has shorter arm and one longer arm.
  3. In acrocentric chromosome the centromere is situated close to its end so it has one extremely short and one very long arm.
  4. Telocentric chromosome has a terminal centromere.

Microbodies:
It is the membrane bound vesicles called microbodies (contain various enzymes) are present in both plant and animal cells.

Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants

Students can Download Chapter 4 Anatomy of Flowering Plants Notes, Plus One Botany Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants

What is plant anatomy?
It is the study of internal structure of plants. In angiosperms, the monocots and dicots are anatomically different.

Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants

The Tissues:
Group of cells having a common origin and function.
Do you agree that all tissue in plants are capable of division?
Some tissues are capable of division they are called meristemetic tissues, while others are capable of divisor , they are called permanent tissues.

Meristemetic Tissue:
They are found in specific region of plant i.e. growing region the tips of roots and shoots
Classification based on the position:

  1. Apical meristem
  2. Inter calary meristem
  3. Lateral meristem.

Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants 1

1. Apical meristem:
In root it is situated at the tip while in shoot it lies in the distant most region of the stem axis. The portion of shoot apical meristem i.e axillary bud present in the axils of leaves forms branch or a flower.

2. Intercalary meristem:
It occurs between mature tissues or base of internode of grasses. The above two meristems are primary meristems because they appear early in the life of a plant.

Grasses in an area are cut and removed by cows, after few days regeneration occurs and new grasses are formed. Why?
Due to the activity of intercalary meristem.

3. Secondary or lateral meristem:
It occurs in the mature regions of roots and shoots of plants particularly in woody axis. Eg-Fascicular vascular cambium, interfascicular cambium and cork-cambium.

For example: In some woody species after few years thickness of plant body increases from 5 inch diameter to 10 inch diameter. Why this happens?
Due to the activity of lateral meristem

What is permanent tissues?
Meristems structurally and functionally specialised and lose the ability to divide. Such cells are termed as permanent tissues.

Permanent Tissues:
Classification:

  • Simple tissues: They are made up of similar kind of cells
  • Complex tissues: They are made up of different kind of cells

Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants

Simple Tissue:
1. Parenchyma:

  • They are isodiametric, spherical, oval, round, polygonal or elongated in shape.
  • Their walls are thin and made up of cellulose.
  • They may either be closely packed or have small intercellular spaces.

Functions:
Photosynthesis, storage and secretion.

 

2. Collenchyma:

  • It occurs just below the epidermal layer.
  • Cells of this tissue are thickened at the corners due to a deposition of cellulose, hemicellulose and pectin.
  • Collenchymatous ceils may be oval, spherical or polygonal and contain chloroplasts.
  • Intercellular spaces are absent.

Function:
Mechanical support.
Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants 3

3. Sclerenchyma:

  • They are thick, dead and lignified with few or numerous pits.
  • They are classified into fibres and sclereids.
  • The fibres are thick-walled, elongated and pointed cells occuring in groups.

Function:
Mechanical support to organs.

Structure and position of sclereids in plants:
They are spherical, oval or cylindrical, highly thickened dead cells with very narrow cavities (lumen). These are found in the fruit walls of nuts; pulp of fruits like guava, pear and sapota; seed coats of legumes and leaves of tea.
Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants 4

Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants

Complex Tissues:
Xylem and phloem are considered as complex tissues in plants
Xylem:

  • It conducts water and minerals from roots to the stem and leaves.
  • It also provides mechanical strength to the plant parts.
  • Gymnosperms lack vessels in their xylem.
  • It is composed of four different kinds of elements

Tracheids, vessels, xylem fibres and xylem parenchyma.
1. Tracheids:
They are dead and without protoplasm.They are elongated or tube like cells with thick and lignified walls and tapering ends. In flowering plants, tracheids and vessels are the main water transporting elements.

2. Vessel:
It is a long cylindrical tube-like structure having lignified walls and a large central cavity. They are devoid of protoplasm and interconnected by perforations in their common walls. The presence of vessels is a characteristic feature of angiosperms.

3. Xylem fibres:
They have highly thickened walls and are dead. These may either be septate or aseptate.

Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants 5

4. Xylem parenchyma”

  • They are cellulosic, living and thin-walled.
  • They store food materials in the form of starch or fat, and other substances like tannins.
  • Radial conduction of water takes place by the ray parenchymatous cells.
  • Primary xylem is of two types – protoxylem and metaxylem. The first formed primary xylem elements are called protoxylem and the later formed primary xylem is called metaxylem.

Difference between endarch and exarch condition:
In stems, the protoxylem lies towards the centre (pith) and the metaxylem lies towards the periphery of the organ. It is called endarch. In roots, the protoxylem lies towards periphery and metaxylem lies towards the centre.lt is called exarch.

Phloem:
It transports food materials, usually from leaves to other parts of the plant. Phloem in angiosperms is composed of

Sieve tube elements, companion cells, phloem parenchyma and phloem fibres.

Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants

Gymnosperms have albuminous cells and sieve cells. They lack sieve tubes and companion cells.
1. Sieve tube elements:

  • They are also long, tube-like structures.
  • Their end walls are perforated to form the sieve plates.
  • A mature sieve element have a large vacuole but lacks a nucleus.
  • The functions of sieve tubes are controlled by the nucleus of companion cells.

Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants 6

2. Companion cells:

  • They are parenchymatous cells closely associated with sieve tube elements.
  • The sieve tube elements and companion cells are connected by pit fields.
  • The companion cells help in maintaining the pressure gradient in the sieve tubes.

3. Phloem Parenchyma:

  • It consist of cylindrical cells with dense cytoplasm and nucleus.
  • The cell wall is composed of cellulose and has pits through which plasmodesmata passes.
  • The phloem parenchyma stores food material and other substances like resins, latex and mucilage. Phloem parenchyma is absent in monocots.

4. Phloem fibres (bast fibres):

  • They are elongated, unbranched, needle like sclerenchymatous cells.
  • At maturity, these fibres lose their protoplasm and become dead.
  • These are generally absent in the primary phloem but are found in the secondary phloem.
Commercially important Phloem fibres are jute, flax and hemp
The first formed primary phloem is called as protophloem
later formed phloem has bigger sieve tubes and is called as metaphloem

The Tissue System:
Based on the of their structure and location, there are three types of tissue systems.

  1. Epidermal tissue system
  2. The ground or fundamental tissue system
  3. Vascular or conducting tissue system.

Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants 7
Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants

1. Epidermal tissue system:
Stomata are present in the epidermis of leaves regulate the process of transpiration and gaseous exchange.
Shape of guard cell in dicot and monocot:
In dicot, it consist of two bean-shaped cells known as guard cells. In grasses(monocot), the guard cells are dumb bell shaped.

  • The outer walls of guard cells are thin and the inner walls are thickened.
  • The guard cells possess chloroplasts and regulate the opening and closing of stomata.
  • Guard cells are surrounded by specialised cells they are known as subsidiary cells.

What is stomatal apparatus?
The stomatal aperture, guard cells and the surrounding subsidiary cells are together called stomatal apparatus.

  • The root hairs help to absorb water and minerals from the soil.
  • On the stem the epidermal hairs are called trichomes.
  • They have secretory function.
  • The trichomes also help to prevent water loss due to transpiration.

2. The Ground Tissue System:

  • It includes parenchyma, collenchyma and sclerenchyma.
  • Parenchymatous cells are usually present in cortex, pericycle, pith and medullary rays in the primary stems and roots.
  • In leaves, the ground tissues are thin-walled chloroplast containing cells called mesophyll.

3. The Vascular Tissue System:
The vascular system consists of phloem and xylem.

Different type bundles:
1. Open vascular bundles:
In dicot stems, Cambium is’present between phloem and xylem.

2. Closed vascular bundle:
In the monocot, the vascular bundles have no cambium present in them. Hence they do not form secondary tissues .

Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants 8

3. Radial bundle:
In roots, xylem and phloem are arranged in an alternate manner on different radii.

4. Conjoint bundle:
In stems and leaves, the xylem and phloem are situated at the same radius of vascular bundles. In this phloem located on the outer side of xylem.

Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants

Anatomy Of Dicotyledonous And Monocotyledonous Plants:
Dicotyledonous Root (eg sunflower root):
Salient features:

  • The outermost layer is epidermis which is unicellular in root hairs.
  • Lower layer is cortex consists of parenchyma cells with intercellular spaces.
  • The innermost layer of the cortex is called endodermis.
  • It comprises a single layer of barrel-shaped cells without any intercellular spaces

Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants 9

Chemical substance in endodermal wall:

  • Its tangential and radial walls have a deposition of water impermeable waxy material-suberin-in the form of casparian strips.
  • Next to endodermis is thick walled pericycle. From thisjateral roots and vascular cambium during the secondary growth originates.
  • The pith is small.
  • Conjuctive tissues are the parenchymatous cells which lie between the xylem and phloem
  • Usually two to four xylem and phloem patches. Later, a cambium ring develops between the xylem and phloem.
  • Stele is the tissues on the inner side of the endodermis such as pericycle, vascular bundles and pith.

Monocotyledonous Root:
The anatomy of the monocot root is similar to the dicot root in many respects.
Some specialities are given below:

  • It has more than six (polyarch) xylem bundles .
  • Pith is large and well developed.

Secondary thickening is most common in dicot plants:
Cambium is present only in dicot plant, it is absent in monocots, so Monocotyledonous roots do not undergo any secondary growth.
Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants 10
Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants

Dicotyledonous Stem:
Salient features:

  1. The outermost protective layer of the stem is epidermis.lt is covered by a thin layer of cuticle.
  2. Epidermis consist of trichomes and stomata.
  3. Cortex lie between epidermis and pericycle. It consists of outer hypodermis, having collenchymatous cells which provide mechanical strength.
  4. Thin walled parenchymatous cells seen below hypodermis.
  5. The innermost layer of the cortex is called the endodermis. It consists of starch grains called as the starch sheath. Inner to endodermis is Pericycle.
  6. Vascular bundles are arranged in ring It consist of xylem and phloem. Cambium lie between these two.
  7. Semi-lunar patches of sclerenchyma occur at the outer part of the phloem.
  8. Vascular bundle is conjoint, open, and endarch.
  9. Pith is seen at the central part of the stem.

Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants 11

Monocotyledonous Stem Salient features:

  • It consist of sclerenchymatous hypodermis and large number of scattered vascular bundles.
  • It is surrounded by a sclerenchymatous bundle sheath
  • Vascular bundles are conjoint and closed.
  • Peripheral vascular bundles are smaller than centrally located ones.
  • The phloem parenchyma is absent and water- containing cavities are present within the vascular bundles.

Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants 12

Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants

Dorsiventral (Dicotyledonous) Leaf:
Salient features:

  • The dorsiventral leaf shows three main parts, namely, epidermis- upper syrface (adaxial epidermis) and lower surface (abaxial epidermis -bears more stomata),
  • Mesophyll.- possesses chloroplasts (It has two types of cells palisade parenchyma and spongy parenchyma) and vascular system.
  • Vascular system is seen in midrib & viens.
  • The vascular bundles are surrounded by a layer of thick walled bundle sheath cells.
  • The veins vary in thickness in the reticulate venation of the dicot leaves.

Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants 13

Isobilateral (Monocotyledonous) Leaf:
The vertical section of isobilateral leaf is similar to that of the dorsiventral leaf It shows some differences.
Salient features:

  1. It has stomata on both the surfaces of the epidermis
  2. Mesophyll is not differentiated into palisade and spongy parenchyma.
  3. The position and function of Bulliform cells: In grasses, upper epidermal cells have specialised colourless cells .they are called bulliform cells. It helps in rolling and unrolling of lamina. When they are flaccid due to water stress, they make the leaves curl inwards to minimise water loss. .
  4. Venation in monocot leaves is parallel.

Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants 14

Secondary Growth:
What you mean by secondary growth?
Dicotyledonous plants shows secondary growth .i.e it increases the girth of plant body. The tissues involved in secondary growth are lateral meristems eg: vascular cambium and cork cambium

Vascular Cambium:
It is seen in between xylem and pholem. it forms a complete ring.

Formation of cambial ring:
Intra fascicular and inter fascicular cambium- Difference:
In dicot stems, cambium present between primary xylem and primary phloem is the intrafascicular cambium. The medullary cells seen in between xylem & phloem become meristematic and forms interfascicular cambium. Thus, a continuous ring of cambium is formed.

Activity of the cambial ring:
The cambial ring cut off new cells towards the inner (secondary xylem) and the outer sides( secondary phloem).

How can you analyse Canbium is more active towards inner side than outer side?
The cambium is more active on the inner side than on the outer, as a result amount of secondary xylem produced is more than secondary phloem. The primary and secondary phloems get gradually crushed due to the continued formation and accumulation of secondary xylem.

At some places, the cambium forms a narrow band of parenchyma, which passes through the secondary xylem and the secondary phloem are called the secondary medullary rays.
Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants 15

Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants

Spring wood and autumn wood:
Spring wood or early wood:
In the spring season, cambium is very active and produces a large number of xylem elements having vessels with wider cavities.This wood is called spring wood.

Autumn wood or late wood:
In winter, the cambium is less active and forms fewer xylem elements that have narrow vessels, This wood is called autumn wood. The spring wood is lighter and autumn wood is darker.

Annual ring in the calculation of age of tree:
The spring wood and autumn wood that appear as alternate concentric rings, constitute an annual ring. Age of tree can be calculate by counting the number of annual rings.

Heartwood – Durable wood?
1. The inner most layers of the stem consist of secondary xylem is dark brown due to deposition of organic compounds like tannins, resins, oils, gums, aromatic substances and essential oils.

2. It is resistant to the attack of microorganisms. This type of wood is called heartwood.

Sap wood:
The outer part of wood is light coloured, functional and and conduct water and minerals . This type of wood is called sap wood.

Cork Cambium:
Due to the activity of vascular cambium, girth of the stem increases. This results the breakdown of outer cortical and epidermis layers .So the new protective tissues are formed by another meristematic tissue called cork cambium or phellogen
Activity of cort cambium & phellogen:
Phellogen cuts off cells on both sides. The outer cells differentiate into cork or phellem while the inner cells differentiate into secondary cortex or phelloderm.

Feature of secondary tissues of phellogen and constituents of Periderm:
The cork is impervious to water due to suberin deposition in the cell wall. The cells of secondary cortex are parenchymatous. Phellogen, phellem, and phelloderm are together known as periderm.

Bark:
It is found exterior to the vascular cambium, including secondary phloem. Bark that is formed early in the season is called early or soft bark. Towards the end of the season late or hard bark is formed.

Lenticels and function:
At certain regions, the phellogen cut off closely arranged parenchymatous cells on the outer side instead of cork cells. These cells rupture the epidermis, and forms openings called lenticels. It helps in the exchange of gases between the outer atmosphere and the internal tissue of the stem.
Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants 16

Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants

Secondary Growth in Roots:
Can you think of formation of vascular cambium is completely secondary in origin?
In the dicot root, the vascular cambium is completely secondary in origin. lt occurs in the later stages of growth. It originates from the tissue located just below the phloem bundles and a portion of pericycle tissue, opposite to protoxylem forming a complete and continuous wavy ring, which later becomes circular.

Secondary growth also occurs in stems and roots ofgymnosperms. But secondary growth does not occur in monocotyledons.
Plus One Botany Notes Chapter 4 Anatomy of Flowering Plants 17

Plus One Botany Notes Chapter 3 Morphology of Flowering Plants

Students can Download Chapter 3 Morphology of Flowering Plants Notes, Plus One Botany Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Botany Notes Chapter 3 Morphology of Flowering Plants

Define Morphology:
It is study of external features of a plant i.e presence of roots, stems, leaves, flowers and fruits.

Plus One Botany Notes Chapter 3 Morphology of Flowering Plants

The Root:
Root system:
In dicotyledonous plants, the direct elongation of the radicle leads to the formation of primary root which bears lateral roots that are secondary, tertiary, etc.
Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 1
1. Tap root system:
The radical elongate and forms primary root or tap root that bears number of lateral roots. It is found in dicot root. eg: the mustard plant.

2. Fibrous root system:
In monocotyledonous plants, the primary root is short lived from there thin fibre roots originates. eg: wheat plant.

3. Adventitious roots:
In grass, Monstera and the banyan tree, roots arise from parts of the plant other than the radicle.
Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 2

Regions of the Root:
1. Region of Root cap:
It is the covering of root apex that protects the tender apex.

2. Region of Meristem:
This is the region just behind the the root cap that is capable of active cell division.

3. Region of elongation:
The cells proximal to this region undergo rapid elongation and enlargement for the growth

4. Region of maturation:
This is proximal to the region of elongation gradually differentiate and mature

5. Region root hairs:
From the region of maturation root hairs arise. These root hairs absorb water and minerals from the soil.
Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 3

Plus One Botany Notes Chapter 3 Morphology of Flowering Plants

Modifications of Root:
Roots are modified for

  1. Mechanical support
  2. Storage of food
  3. Respiration

1. Mechanical support:
(a) Prop roots:
In banyan tree, adventitious roots are modified and provide mechanical support

(b) Stilt roots:
In maize and sugarcane adventitious roots are supporting and coming out from the lower nodes of the stem. .

2. Storage of food:
In carrot, turnips tap roots are modified for food storage. In sweet potato adventitious roots are swollen and store food.

3. Respiration:
Rhizophora growing in swampy areas, many roots come out of the ground and grow vertically upwards. Such roots are called pneumatophores.
Function:
It help in the process of respiration.
Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 4
Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 5

The Stem:
Salient features:

  1. The stem arise from the plumule of the embryo of a germinating seed.
  2. The stem bears nodes and internodes.
  3. The region of the stem where leaves are born are called nodes while internodes are the portions between two nodes.

Function:
Support leaves, flowers and fruits. It also conducts water, minerals and do photosynthesis.

Plus One Botany Notes Chapter 3 Morphology of Flowering Plants

Modifications of Stem:
1. Storage of food:
Underground stems of potato, ginger, turmeric, zaminkand, Colocasia are modified to store food

2. Climbing:
Stem tendrils which develop from axillary buds, are slender and spirally coiled that help the plants to climb. eg: in gourds (cucumber, pumpkins, watermelon) and grapevines.

3. Protection:
Axillary buds of stem are modified into woody, straight and pointed thorns. eg: in Citrus, Bougainvillea Thev nrotect Dlants from browsina animals
Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 6
4. Photosynthesis:
Some stems are lattened (Opuntia), or fleshy cylindrical (Euphorbia) structures. They contain chlorophyll and carry out photosynthesis.

5. Vegetative propagation:

  • In grass and strawberry, etc. stem spread to new niches and when older parts die new plants are formed.
  • In mint and jasmine lateral branch arises from the base of the main axis and after growing aerially and arch downwards to touch the ground.
  • In Pistia and Eichhornia the lateral branch with short internodes and each node bearing a rosette of leaves and a tuft of roots
  • In banana, pineapple and Chrysanthemum, the lateral branches originate from the basal underground portion of the main stem, grow horizontally beneath the soil and then come out obliquely upward giving rise to leafy shoots.

The Leaf:
Salient features:

  1. It is the flattened structure develops at the node and bears a bud in its axil.
  2. The axillary bud later develops into a branch.
  3. They are the most important vegetative organs for photosynthesis.
  4. some plants leaf base bear two lateral stipules.
  5. In monocotyledons, the leaf base expands into a sheath covering the stem.
  6. In some leguminous plants the leaf base become swollen, which is called the pulvinus.
  7. The lamina or the leaf blade is the green expanded part of the leaf with veins and veinlets.
  8. The middle prominent vein, which is known as the midrib.

Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 7

Function of veins:
Veins act as channels of transport for water, minerals and food materials.
A typical leaf consists of three main parts:

  • Leaf base
  • petiole
  • lamina

Plus One Botany Notes Chapter 3 Morphology of Flowering Plants

Venation:
1. Reticulate Venation:
The arrangement of veins and the veinlets in the lamina of leaf. Veinlets repeatedly branched to form a network. eg: dicotyledonous plants.

2. Parallel Venation:
When the veins run parallel to each other within a lamina. eg: monocotyledons plants.
Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 8

Types of Leaves:

  1. Siimple leaf: In this lamina is entire or the incisions do not touch the midrib.
  2. Compound leaf: In this incisions of the lamina reach up to the midrib breaking it into a number of leaflets.

Can you see the bud in the axil of leaflet of compound leaf?
A bud is not present in the axil of leaflets of the compound leaf.

Two types of compound leaves:

  1. Pinnately compound leaf: Number of leaflets are present on a common axis, the rachis, which represents the midrib of the leaf eg neem.
  2. Palmately compound leaf: In this leaflets are attached at the tip of petiole, eg silk cotton.

Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 9

Phyllotaxy:
It is the arrangement of leaves on the stem or branch Three types of phyllotaxy in plants alternate, opposite and whorled.

  1. Alternate type: A single leaf arises at each node in alternate manner. eg: china rose, mustard and sunflower.
  2. Opposite type: A pair of leaves arise at each node and lie opposite to each other. eg: Calotropis and guava.
  3. Whorled type: More than two leaves arise at a node. eg: Alstonia.

Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 10

Plus One Botany Notes Chapter 3 Morphology of Flowering Plants

Modifications of Leaves:

  1. Food storage: The fleshy leaves of onion and garlic store food.
  2. Protection: The spines are developed in cacti act as organ of defence
  3. Climbing: In peas Leaves are modified into tendrils for climbing
  4. Photosynthesis: In Australian acacia, the leaves are small and short-lived. The petioles in these plants expand become green and synthesise food
  5. Insect capture: In pitcher plant and venus-fly trap (insectivorous plants) leaves are modified for Capturing insects.

Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 11

The Inflorescence:
The arrangement of flowers on the floral axis is termed as inflorescence. Two major types of inflorescences are

  1. Racemose
  2. Cymose.

How will you differentiate recemose inflorescence from cymose?
In racemose type, the main axis continues to grow, the flowers are arranged in an acropetal succession. In cymose type, the main axis terminates in a flower. The flowers arranged in a basipetal order.
Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 12

The Flower:
The flower is the reproductive unit in the angiosperms. It consists of different kinds of whorls (calyx, corolla, androecium and Gynoecium) arranged successively on the swollen end of the stalk or pedicel, called thalamus or receptacle.

What are the accessory and reproductive organs?
Calyx and corolla are accessory organs,while androecium and gynoecium are reproductive organs.

Did you see single accessory organ of a flower:
In lily plant, the calyx and corolla are not distinct, it is called as perianth. This is the single accessory organ of a flower. When a flower has both androecium and gynoecium, it is bisexual. A flower having either only stamens or only carpels is unisexual.
1. Actinomorphic Flower:
A flower can be divided into two equal radial halves in any radial plane passing through the centre, eg: mustard, datura, chilli.

Plus One Botany Notes Chapter 3 Morphology of Flowering Plants

2. Zyqomorphic:
A flower can be divided into two similar halves only in one particular vertical plane, eg: pea, gulmohur, bean, Cassia.

3. Asymmetric (irregular):
A flower cannot be divided into two similar halves by any vertical plane passing through the centre, as in canna. Afloweristrimerous, tetramerous or pentamerous when the floral appendages are in multiple of 3, 4 or 5, respectively.

Bracteate and ebracteate flower:
Flowers with reduced leaf found at the base of the pedicel, are called bracteate and those without bracts, ebracteate.

Classification of flower:
It is based on the position of calyx, corolla and androecium in respect of the ovary on thalamus
1. Hypogynous flower:
The position of gynoecium is highest when compared to other. The ovary in such flowers is said to be superior, eg: mustard, china rose and brinjal.

2. Perigynous flower:
The position of gynoecium is situated in the centre and other parts of the flower are located on the rim of the thalamus almost at the same level. The position of ovary is half inferior, eg: plum, rose, peach.

3. Epigynous flowers:
The margin of thalamus grows upward and other parts of flower arise above the ovary. The position of ovary is inferior. eg: guava and cucumber, and the ray florets of sunflower.
Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 13

Parts of a Flower:
Each flower has four floral whorls -calyx, corolla, androecium and gynoecium.
Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 14

Plus One Botany Notes Chapter 3 Morphology of Flowering Plants

Calyx:
Act as protective whorl:
The calyx is the outermost whorl of the flower and segments are called sepals. The sepals are green, leaf like and protect the flower in the bud stage. The calyx may be gamosepalous (sepals united) or polysepalous (sepals free).

Corolla:
Act as an attractive whorl:
Petals are brightly coloured that attract insects for pollination. Corolla may be free (polypetalous) or united (gamopetalous).

Aestivation:
The mode of arrangement of sepals or petals in floral bud is known as aestivation. The main types of aestivation are:

  1. Valvate
  2. Twisted
  3. Imbricate
  4. Vexillary.

Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 15

  1. In valvate sepals or petals in a whorl just touch one another at the margin, without overlapping, Eg -Calotropis
  2. In twisted the one margin of the appendage overlaps the next one and so on. g. china rose, lady’s finger and cotton
  3. In imbricate the margins of sepals or petals overlap one another but not in any particular direction. eg: Cassia and gulmohur

Can vou find out aestivation type in papillionaceous corolla?
There are five petals, the largest (standard) overlaps the two lateral petals (wings) which in turn overlap the two smallest anterior petals (keel). This is vexillary aestivation; Eg pea and bean flowers.

Plus One Botany Notes Chapter 3 Morphology of Flowering Plants

Androecium:
Structure of stamen:
Androecium is composed of stamens. Stamen is the male reproductive organ consists of a filament and an anther. Each anther is usually bilobed and each lobe has two chambers, the pollen-sacs. The pollen grains are produced in pollen-sacs. A sterile stamen is called staminode.

Differentiate between epibetalous and epiphvllous condition:
When stamens are attached to the petals, they are epipetalous as in brinjal, or epiphyllous when attached to the perianth as in the flowers of lily.

Free and fused nature of stamens:
The stamens in a flower remain free called as polyandrous. If the stamens are united into one bundle called as monoadelphous. eg: china rose, or two bundles called as diadelphous eg: pea, or into more than two bundles called as polyadelphous eg: citrus.

Variation in the length of filaments:
eg: Salvia and mustard.

Gynoecium:
Structure of carpel/pistil:
Gynoecium is the female reproductive part of the flower and is made up of one or more carpels. Acarpel consists of three parts namely stigma, style and ovary. Ovary is the enlarged basal part, on which lies the elongated tube, the style.

The style connects the ovary to the stigma. The stigma is the receptive surface for pollen grains. Each ovary bears one or more ovules attached to a flattened, cushion-like placenta.
Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 16

Free and fused nature of carpel:
If carpels are free they are called apocarpous, eg lotus and rose. If carpels are fused they are called syncarpous. eg: mustard and tomato.

What happens to ovule and ovary after fertilization?
After fertilisation, the ovules develop Into seeds and the ovary matures into a fruit.

Plus One Botany Notes Chapter 3 Morphology of Flowering Plants

Placentation:
The arrangement of ovules within the ovary is known as placentation. Different types of placentation are marginal, axile, parietal, basal, central and free central.

Marginal placentation: the placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge eg- pea.
Axile placentation: When the placenta is axial and the ovules are attached to it in a multilocular ovary eg china rose, tomato and lemon.
Parietal placentation: Ovary is one-chambered and the ovules develop on the inner wall of the ovary e.g., mustard and Argemone.
Free central placentation: When the ovules are borne on central axis and septa are absent Eg Dianthus and Primrose
Basal placentation: The placenta develops at the base of ovary and a single ovule is attached to it eg sunflower, marigold

The Fruit:
It is a ripened ovary developed after fertilisation.
Parthenocarpic fruit:
If a fruit is formed without fertilisation of the ovary, it is called a parthenocarpic fruit. The fruit consists of a wall called pericarp and seeds.

Meaning of Drupe:
Fruit that develops from monocarpellary superior ovaries and are one seeded. Eg:- mango and coconut.

Different layers of pericarp:
In mango the pericarp is well differentiated into an outer thin epicarp, a middle fleshy edible mesocarp and an inner stony hard endocarp. In coconut fruit is drupe, the mesocarp is fibrous.
Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 17

The Seed:
Seed consists of a seed coat and an embryo. The embryo is made up of a radicle, an embryonal axis, one cotyledons as in wheat, maize or two cotyledons as in gram and pea.

Plus One Botany Notes Chapter 3 Morphology of Flowering Plants

Structure of a Dicotyledonous Seed:
The seed coat has two layers, the outer testa and the inner tegmen. The hilum is a scar on the seed coat .Above the hilum is a small pore called the micropyle. It consists of an embryonal axis and two cotyledons. The cotyledons are fleshy and contains reserve food materials. At the two ends of the embryonal axis are present the radicle and the plumule.

What is non endospermic seed?
In plants such as bean, gram and pea, the endosperm is not present in mature seeds and such seeds are called non endospermous.
Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 18

Structure of Monocotyledonous Seed:
Monocotyledonous seeds are endospermic but it is non-endospermic in orchids. The seed coat is membranous and fused with the fruit wall. The outer covering of endosperm separates the embryo by a proteinous layer called aleurone layer The embryo is situated in one end of the endosperm.

It consists of Vy one large and shield shaped cotyledon known as scutellum and a short axis with a plumule and a radicle. The plumule is enclosed in sheaths called coleoptile and radicle are enclosed in sheaths called as coleorhiza.
Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 19

Some Technical Description Of A Typical Flowering Plant:
In the floral formula, Br stands for bracteate K stands for calyx, C for corolla, P for perianth, A for androecium and G for Gynoecium, for superior ovary and for inferior ovary, for male, for female, for bisexual plants, for for actinomorphicand forforzygomorphic nature of flower

Description Of Some Important Families:
Fabaceae (Papilonoideae ):
It is a subfamily of family Leguminosae.

Vegetative Characters:

  • Stem: Erect or climber
  • Leaves: alternate, pinnately compound or simple; leaf base, pulvinate; stipulate; venation reticulate.

Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 20
Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 21

Economic importance:
Sources of pulses (gram, arhar.sem, moong, soyabean; Edible oil (soyabean, groundnut); dye (indigofera); Fibres (sunhemp); Fodder (Sesbania, Trifolium), Ornamentals (lupin, sweet pea) Medicine (muliathi).

Plus One Botany Notes Chapter 3 Morphology of Flowering Plants

Solanaceae (‘potato family’):
Vegetative Characters:
1. Stem:
herbaceous rarely woody, aerial; erect, cylindrical, branched, solid or hollow, hairy or glabrous, underground stem in potato (Solatium tuberosum).

2. Leaves:
alternate, simple, rarely pinnately compound, exstipulate; venation reticulate

Floral Characters:

  • Inflorescence: Solitary, axillary or cymose as in Solanum
  • Flower: bisexual, actinomorphic
  • Calyx: sepals five, united, persistent, valvate aestivation
  • Corolla: petals five, united; valvate aestivation
  • Androecium: stamens five, epipetalous
  • Gynoecium: bicarpellary, syncarpous; ovary superior, bilocular, placenta swollen with many ovules
  • Fruits : berry or capsule
  • Seeds: many, endospermous.

Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 22 (2)
Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 23

Economic Importance:
source of food (tomato, brinjal, potato)spice (chilli); Medicine (belladonna, ashwagandha) Fumigatory (tobacco); ornamentals (petunia).

Lilaceae (‘Lily family’):
Vegetative characters:
Perennial herbs with underground bulbs/corms/rhizomes. Leaves mostly basal, alternate, linear, exstipulate with parallel venation.

Floral characters:

  • Inflorescence: solitary/cymose; often umbellate clusters.
  • Flower: bisexual; actinomorphic
  • Perianth: tepal six (3 + 3), often united into tube valvate aestivation.
  • Androcium: stamen six, 3 + 3
  • Gynoecium: tricarpellary, syncarpous, ovar ovules; axile placentation.
  • Fruit: capsule, rarely berry
  • Seed: endospermous

Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 24
Plus One Botany Notes Chapter 3 Morphology of Flowering Plants 25

Economic Importance:
Ornamentals (tulip, Gloriosa), Source of medicine (Aloe), Vegetables (Asparagus), and colchicine (Colchicum autumnale).

Plus One Botany Notes Chapter 2 Plant Kingdom

Students can Download Chapter 2 Plant Kingdom Notes, Plus One Botany Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Botany Notes Chapter 2 Plant Kingdom

Plus One Botany Notes Chapter 2 Plant Kingdom

Different Plant Groups:

  1. Algae
  2. Bryophytes
  3. Pteridophytes
  4. Gymnosperms
  5. Angiosperms.

Types of classification:
1. Artificial system of classification:
The systems of classification based morphological characters such as habit, colour, number and shape of leaves, etc i.e based on vegetative characters or on the androecium structure. eg: Linnaeus classification.

2. Natural system of classification:
The systems of classification based on not only the external features, but also internal features, like ultrastructure, anatomy, embryology and phytochemistry. eg: George Bentham and Joseph Dalton Hookers classification

3. Phylogenetic system of classification:
The systems of classification based on evolutionary relationships between the various organisms. eg: Englerand prantl.

Taxonomy in modern approach:
1. Numerical Taxonomy
In this, number and codes are assigned to all the characters and the data are processed. This is carried out using computers based on all observable characteristics.

2. Cytotaxonomy:
In this cytological information like chromosome number, structure and behavior are considered.

3. Chemotaxonomy:
It is based on chemical constituents of the plant.

1. Algae:
Characterestic features:
Algae are chlorophyll-bearing, simple, thalloid, autotrophic and largely aquatic (both fresh water and marine) organisms.

Size of algal forms:

  1. Microscopic unicellular forms eg Chlamydomonas,
  2. Colonial forms eg Volvox
  3. Filamentous forms eg Ulothrix and Spirogyra.

Plus One Botany Notes Chapter 2 Plant Kingdom

Reproduction:
1. Vegetative reproduction:
It occures by fragmentation. Each fragment develops into a thallus. .

2. Asexual reproduction:
lt occures by the production zoospores. They are flagellated (motile) and on germination gives rise to new plants.

3. Sexual reproduction:
It takes place through fusion of two gametes.
Plus One Botany Notes Chapter 2 Plant Kingdom 1

(A) Isogamous:
These gametes are flagellated and similar in size (as in Chlamydomonas) or non-flagellated (non-motile) but similar in size (as in Spirogyra).

(B) Anisogamous:
It is the fusion of two gametes dissimilar in size. eg: species of Chlamydomonas

(C) Oogamous:
It is the fusion between one large, non-motile (static) female gamete and a smaller, motile male gamete eg: Volvox, Fucus.

Economic imoportance:

  1. Half of the total carbon dioxide fixation on earth is carried out by algae through photosynthesis.
  2. Many species of Porphyra, Laminaria and Sargassum are among the 70 species of marine algae used as food.
  3. Certain marine brown and red algae produce large amounts of hydrocolloids (water holding substances), eg: algin (brown algae) and carrageen (red algae) are used commercially.
  4. Agar obtained from Gelidium and Gracilaria are used to grow microbes and in preparations of ice-creams and jellies.
  5. Chlorella and Spirullina are unicellular algae, rich in proteins and are used as food by space travellers.

Three main classes of algae:
Plus One Botany Notes Chapter 2 Plant Kingdom 2

Plus One Botany Notes Chapter 2 Plant Kingdom

Chlorophyceae (Green algae):
Salient features:

  1. The plant body may be unicellular, colonial or filamentous. The dominant green pigments are chlorophyll a and b.
  2. The chloroplasts may be discoid, plate-like, reticulate, cup-shaped, spiral or ribbon-shaped in different species.
  3. The storage bodies called pyrenoids located in the chloroplasts. Pyrenoids contain protein besides starch.
  4. Green algae have a rigid cell wall made of an inner layer of cellulose and an outer layer of pectose.
  5. Vegetative reproduction usually takes place by fragmentation.
  6. Asexual reproduction is by flagellated zoospores produced in zoosporangia.
  7. The sexual reproduction may be isogamous, anisogamous or oogamous.

eg: Chlamydomonas, Volvox, Ulothrix, Spirogyra and Chara.

Phaeophyceae (Brown algae):
Salient features:

  1. They are mainly found in marine habitats.
  2. The size of plant body range from simple branched, filamentous forms (l=ctocarpus) to profusely branched forms such as kelDs (height 100 metres).
  3. They possess chlorophyll a, c, carotenoids and xanthophylls. Fucoxanthin is present in large amount.
  4. Food is stored as complex carbohydrates in the form of laminarin or mannitol.
  5. The vegetative cells with cellulosic wall is covered on the outside by a gelatinous coating of algin.
  6. The plant body is attached to the substratum by a holdfast, and has a stalk, the stipe and leaf like photosynthetic organ-the frond.
  7. Vegetative reproduction takes place by fragmentation.
  8. Asexual reproduction is by biflagellate zoospores that are pear-shaped and have tyvo unequal laterally attached flagella.
  9. Sexual reproduction may be isogamous, anisogamous or oogamous.
  10. The gametes are pyriform (pear-shaped) and bear two laterally attached flagella.

eg: Ectocarpus, Dictyota, Laminaria, Sargassum and Fucus.

Rhodophyceae(Red algae):
Salient features:

  1. Majority are marine and found in the warmer areas.
  2. The red thalli of most of the red algae are multicellular. The chlorophyll pigments are chi a,chi d.
  3. The dominant red pigment is r-phycoerythrin.
  4. The food is stored as floridean starch similar to amylopectin and glycogen in structure.
  5. The red algae usually reproduce vegetatively by fragmentation.
  6. They reproduce asexually by non-motile spores and sexually by non-motile gametes.
  7. Sexual reproduction is oogamous and accompanied by complex post fertilisation developments.

eg: Polysiphonia, Porphyra, Gracilaria and Gelidium.

2. Bryophytes:
Amphibians of the plant kingdom?
Because these plants are found in damp, humid and shaded localities and dependent on water for sexual reproduction.
Salient features:

  • Thallus is prostrate or erect, and attached to the substratum by unicellular or multicellular rhizoids.
  • They lack true roots, stem or leaves.
  • The main plant body of the bryophyte is haploid. It produces gametes, hence is called a gametophyte.
  • The male sex organ is multicellular antheridium. They produce biflagellate antherozoids.
  • The female sex organ called archegonium it is flask-shaped and produces a single egg.

Plus One Botany Notes Chapter 2 Plant Kingdom

Sexual reproduction:
Antherozoid moves through water they come in contact with archegonium and fuses with the egg to produce the zygote. Zygotes produce a multicellular body called a sporophyte.
Plus One Botany Notes Chapter 2 Plant Kingdom 3

What is the nature and development of sporophytes of bryophytes?
The sporophyte is not free-living but attached to the photosynthetic gametophyte Some cells of the sporophyte undergo reduction division (meiosis) to produce haploid spores. These spores germinate to produce gametophyte.

Economic importance:

  1. They play an important role in plant succession on bare rocks/soil. They decompose rocks making the substrate suitable for the growth of higher plants.
  2. Some mosses provide food for herbaceous mammals, birds and other animals.
  3. Sphagnum, a moss, provide peat that is used as fuel, and because of their capacity to hold water as packing material for trans-shipment of living material.
  4. Mosses form dense mats on the soil hence it prevents soil erosion.

The bryophytes are divided into liverworts and mosses.
Liverworts:
Growing locality:
The liverworts grow in moist, shady habitats such as banks of streams, marshy ground, damp soil, bark of trees and deep in the woods.

What is nature of plant body?
The plant body of a liverwort is thalloid, eg: Marchantia.

Asexual reproduction in liverworts takes place by fragmentation of thalli, or by the formation of specialised structures called gemmae

Features of Gemmae and its development:
Gemmae are green, multicellular, asexual buds. It is detached from the parent body and germinate to form new individuals.

Structure of sporophvte and spore development:
The sporophyte is differentiated into a foot, seta and capsule. After meiosis, spores are produced within the capsule. These spores germinate to form free-living gametophytes.

Mosses:
Spore germination and protonema:
In the life cycle of bryophytes, spore germinate and forms a creeping, green, branched and a filamentous stage called protonema. The second stage is the leafy stage, which develops from the secondary protonema as a lateral bud.

Plus One Botany Notes Chapter 2 Plant Kingdom

Features of leafy stage:
They consists of spirally arranged leaves and multicellular branched rhizoids. This stage bears the sex organs. It is the true gametophyte.

Vegetative reproduction:
It takes place by fragmentation and budding in the secondary protonema.

Sexual reproduction.
In sexual reproduction, the sex organs are antheridia and archegonia. After fertilisation, the zygote develops into a sporophyte, consisting of a foot, seta and capsule.

Which group of brvophvte shows well developed sporophyte?
The sporophyte in mosses is more elaborate than that in liverworts. The mosses have an elaborate mechanism of spore dispersal. eg: Funaria, Polytrichum and Sphagnum

3. Pteridophytes:
Salient features:

  1. The Pteridophytes are the first terrestrial plants that possess vascular tissues – xylem and phloem. This group includes horsetails and ferns.
  2. They are frequently grown as ornamentals.
  3. The pteridophytes are found in cool, damp, shady places and require water for fertilisation .
  4. The main plant body is a sporophyte which is differentiated into true root, stem and leaves .
  5. The leaves in pteridophyta are small (microphylls) as in Selaginella or large (macrophylls) as in ferns.
  6. The sporophytes bear sporangia by leaf-like appendages called sporophylls.
  7. In some cases sporophylls forms distinct compact structures called strobili or cones (Selaginella, Equisetum).
  8. The sporangia produce spores by meiosis in spore mother cells.
  9. The spores germinate to give rise multicellular, free-living, photosynthetic thalloid gametophytes called prothallus.
  10. The gametophytes bear male and female sex organs called antheridia and archegonia, respectively.

Sexual reproduction:
How do the sporophytes form?
Water is required for transfer of antherozoids to the mouth of archegonium. Fusion of male gamete with the egg present in the archegonium result in the formation of zygote. It undergoes divisions and forms multicellular well-differentiated sporophyte which is the dominant phase of the pteridophytes.
Plus One Botany Notes Chapter 2 Plant Kingdom 4

Plus One Botany Notes Chapter 2 Plant Kingdom

Distiquish between homosporous and heterosporous type or Heterospory is considered as important step in evolution why?
Majority members produce spores are of similar kinds such plants are called homosporous. Few members produce two kinds of spores, macro (large) and micro (small) spores, are-known as heterosporous. eg: Selaginella and Salvinia.

The megaspores and microspores germinate and give rise to female and male gametophytes, respectively. The development of the zygotes into young embryos take place within the female gametophytes. This event is a precursor to the seed habit considered an important step in evolution..
The pteridophytes are further classified into four classes:

  1. Psilopsida(Psilotum)
  2. Lycopsida (Selaginella, Lycopodium)
  3. Sphenopsida (Equisetum
  4. Pteropsida (Dryopteris, Pteris, Adiantum).

4. Gymnosperms:
Salient features:
1. They are naked seed bearing plants in which the ovules are not enclosed by ovary wall and remain exposed.

2. Tap roots have fungal association in the form of mycorrhiza (Pinus), while in some others (Cycas) small specialized roots called coralloid roots are associated with N2-fixing cyanobacteria.

3. The stems are unbranched (Cycas) or branched (Pinus, Cedrus).
Plus One Botany Notes Chapter 2 Plant Kingdom 5
4. The leaves are well-adapted to withstand extremes of temperature, humid ity and wind. .
How can conifers adapt to live in extreme temperature condition or water deficient soil?

  • In conifers, the needle-like leaves that reduce the surface area. .
  • Thick cuticle and
  • sunken stomata

All these characters help to reduce water loss.

5. In Cycas the pinnate leaves persist for a few years.

6. They produce haploid microspores and megaspores i.e heterosporous. These spores are produced within sporangia that are borne omsporophylls which are arranged spirally along an axis to form compact strobili or cones. The strobili bearing microsporophylls and microsporangia are called male strobili.

The microspores develop into a male gametophytic generation. This reduced gametophyte is called a pollen grain. The pollen grain is released from the microsporangium. The cones bearing megasporophylls with ovules or megasporangia are called female strobili.

7. The male or female cones borne on the same tree (Pinus) or on different trees (Cycas).

Development of female qametophyte:
The ovules are borne on megasporophylls that contains nucellus. The megaspore mother cell of nucellus divides meiotically to form four megaspores. One of the megaspores enclosed within the megasporangium (nucellus) develops into a multicellular female gametophyte that bears two or more archegonia
1. The male and the female gametophytes remain within the sporangia retained on the sporophytes.

2. The pollen tube carrying the male gametes grows towards archegonia in the ovules and discharge their contents near the mouth of the archegonia. Following fertilisation, zygote develops into an embryo and the ovules into seeds. These seeds are not covered.

Which is the tallest tree species in world?
Giant redwood tree Sequoia is one of the tallest tree species.
Plus One Botany Notes Chapter 2 Plant Kingdom 6

Plus One Botany Notes Chapter 2 Plant Kingdom

5. Angiosperms (Flowering plants):
Salient features:
1. In this the seeds are enclosed by fruits.
Range of size:

  • Microscopic-Wolfie
  • Tall trees- Eucalyptus(o\ier 100 metres).

2. Two classes in angiosperms:

  • Dicotyledons (two cotyledons in their seeds)
  • Monocotyledons (one cotyledon)

3. The male sex organs in a flower is the stamen. Each stamen consists of a slender filament with an anther at the tip. The anthers produce pollen grains.

4. The female sex organs is the pistil or the carpel. Pistil consists of an ovary enclosing one to many ovules. The highly reduced female gametophytes (embryosacs) found within ovules.

5. Typical embryosac is 7 celled and 8 nucleate Each embryo-sac has a three-celled egg apparatus – one egg cell and two synergids, three antipodal cells and two polar nuclei. The polar nuclei eventually fuse to produce a diploid secondary nucleus. The cells of an embryo-sac is haploid.
Plus One Botany Notes Chapter 2 Plant Kingdom 7

Pollination and pollen tube:
Pollen grain from anther falls on the stigma of a pistil is termed as pollination. The pollen grains germinate and produce pollen tubes that reach the ovule. The pollen tubes enter the embryo-sac where two male gametes are discharged.

Double fertilization:
What are the products and process of double fertilization?
One of the male gametes fuses with the egg cell to form a zygote. This is called syngamy. The other male gamete fuses with the diploid secondary nucleus to produce the triploid primary endosperm nucleus (PEN). This is called Triple fusion. Because of the involvement of two fusions, this event is termed as double fertilization.

Post fertilization changes and significance of edosperm:
The zygote develops into an embryo and the PEN develops into endosperm which provides nourishment to the developing embryo. The synergids and antipodals degenerate after fertilisation. After fertilization ovules develop into seeds and the ovaries develop into fruits.
Plus One Botany Notes Chapter 2 Plant Kingdom 8

Plant Life Cycles And Alternation Of Generations:
In plants, both haploid and diploid cells can divide by mitosis. This ability leads to the formation of different plant bodies – haploid and diploid.

1. Haplontic life cycle:
How do gametophyte forms?
Meiosis in the zygote results in the formation of haploid spores. Then, these spores are divide mitotically and form the gametophyte.

What is the nature of sporophyte and gametophyte?
Sporophytic generation is represented only by the one-celled zygote. The dominant, photosynthetic phase is the free-living gametophyte.
Plus One Botany Notes Chapter 2 Plant Kingdom 9

2. Diplontic life cycle What is the nature of sporophyte and qametophyte?
The diploid sporophyte is the dominant, photosynthetic, independent phase of the plant. The gametophytic phase is represented by the single to few-celled haploid gametophyte. eg: gymnosperms and angiosperms.

3. Haplo-diplontic:
It is an intermediate condition in which both phases are multicellular and often free-living.

What is the nature of both sporophyte and gametophyte?
A dominant, independent, photosynthetic phase is represented by a haploid gametophyte and it alternates with the short lived multicelluler sporophyte dependent on the gametophyte. eg: Bryophytes and pteridophytes.

Algae in haplo-diplontic and diplontic stage:

  • Ectocarpus, Polysiphonia and kelps are haplo-diplontic.
  • Fucus, an alga is diplontic.

Plus One Botany Notes Chapter 2 Plant Kingdom 10

Plus One Botany Notes Chapter 1 Biological Classification

Students can Download Chapter 1 Biological Classification Notes, Plus One Botany Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Botany Notes Chapter 1 Biological Classification

Two kingdom classification:

  • It was proposed by Linnaeus, include two Kingdoms-Plantae & Animalia.
  • In two kingdom classification following things are not considered

Cell structure, nature of wall, mode of nutrition, habitat methods of reproduction and evolutionary relationship .

Plus One Botany Notes Chapter 1 Biological Classification

Five kingdom classification:

  • It was first proposed by R H.Whittaker (1969).
  • It includes Monera, Protista, Fungi, Plantae and Animalia
  • Blue green algae are placed in kingdom Monera.
  • Chlamydomonas, Chlorella with Paramoecium and Amoeba are placed in kingdom protista
  • Chlorophyll less and non cellulosic (chitin)type plants are placed in kingdom Fungi
  • All photosynthetic plants are placed in-kingdom plantae
  • All animals with mode of nutrition(ingestion) placed in kingdom animalia.
  • The characteristics of classification are
1. Cell structure
2. Thallus Organization
3. Mode of nutrition
4. reproduction and
5. Phylogenetic relationships

 

Plus One Botany Notes Chapter 1 Biological Classification 1
Kingdom monera:

Types of bacteria:
Based on shape, bacteria are of 4 types

  1. Spherical – Coccus
  2. Rod – shaped – Bacillus
  3. Comma – shaped – Vibrium
  4. Spiral – Spirillum.

Plus One Botany Notes Chapter 1 Biological Classification 2

Based on nutrition, bacteria are of 3 types:

  1. Photosynthetic autotrophic: Bacteria can synthesise their own food by using chlorophyll in the presence of light.
  2. Chemosynthetic autotrophic: Bacteria can synthesise their own food from inorganic substrates.
  3. Heterotrophs: They are depend on other organisms for food.

Archaebacteria:

  • These bacteria can live in extreme conditions.
  • Its cell wall structure is different from other bacteria

Plus One Botany Notes Chapter 1 Biological Classification

Types of archaebacteria:

  1. Halophiles: They are found in salty areas
  2. Thermoacidophiles: They are found in hot springs.
  3. Methanogens: They are found in marshy areas and guts of ruminant animals eg-cows, buffaloes etc.

Importance in industry:
They are responsible for the production of methane (biogas) from the dung.

Eubacteria Cyanobacteria (blue-green algae):

  • They have chlorophyll a similar to green plants called as photosynthetic autotrophs.
  • Some of them found in polluted water bodies.

Plus One Botany Notes Chapter 1 Biological Classification 3

Significance of cyanobacteria:
They can fix atmospheric nitrogen in specialised cells called heterocysts and increases fertility of soil eg: Nostoc and Anabaena

Chemosynthetic autotrophs:
They oxidise various inorganic substances such as nitrates, nitrites and ammonia and use the released energy for their ATP production.

Significance chemosynthetic autotrophs:
They play a great role in the recycling of nutrients like nitrogen, phosphorous, iron and sulphur.

Heterotrophic bacteria:

  • They depend upon others for getting energy.
  • Most of them are decomposers.
  • They are helpful in making curd from milk, production of antibiotics, fixing nitrogen in legume roots, etc.

Disease caused by bacteria:
Some are pathogens causing disease to plants and animals, eg: Cholera, typhoid, tetanus, and citrus canker in plants.

Cell division in bacteria:
Reproduction:

  • Bacteria reproduce mainly by fission.
  • Some bacteria produce spores during unfavourable conditions.
  • In sexual reproduction, transfer of DNA from one bacterium to the other takes place

Mycoplasmas:
Salient features:

  • They are the smallest living cells can survive without oxygen
  • They are pathogenic in animals and plants
  • They lack a cell wall.

Plus One Botany Notes Chapter 1 Biological Classification

Kingdom Protista:
Salient features:

  • They are single-celled eukaryotes.
  • Their cell body contains a well defined nucleus and other membrane-bound organelles.
  • They are mainly aquatic.

Types of protist:
The kingdom include chrysophytes, Dianoflagellates, Euglenoids, Slime moulds and Protozoans.

Chrysophytes:

  • They are diatoms(chief ‘producers’ in the oceans) and golden algae (desmids).
  • Most of them are photosynthetic.

Salient features:

  • In diatoms the cell walls form two thin overlapping shells,which fit together as in a soap box.
  • Their cell wall contain silica

Economic value:
Their cell wall deposited in ocean floor over billions of years in large amount called as ‘Diatomaceous earth’. It is used in polishing, filtration of oils and syrups.

Dinoflagellates:
Salient features:

  • They are marine and photosynthetic
  • Most of them have two flagella one lies longitudinally and the other transversely.

Harmful effects:

  • Red dianoflagellates -Gonyaulax undergoes rapid multiplication and sea appear red (red tides).
  • Toxins released by them kill other marine animals such fishes.

Euglenoids:
Salient features:

  • They are fresh water organisms found in stagnant water.
  • Pigments of Euglenoids are identical to those of higher plants.
  • They have a protein rich layer called pellicle which makes their body flexible.
  • They have two flagella, a short and a long one.

Mode of nutrition:
They are photosynthetic in the presence of sunlight (autotrophic) and predating on other smaller organisms in the absence of sunlight (heterotrophs). Hence nutrition is mixotrophic. Example: Euglena.
Plus One Botany Notes Chapter 1 Biological Classification 4

Slime Moulds:
Salient features:

  1. They are saprophytic protists.
  2. They form an aggregation during favourable conditions called plasmodium which may grow and spread over several feet.
  3. The plasmodium differentiates and forms fruiting bodies bearing spores at their tips during unfavourable conditions.
  4. They are resistant and survive for many years under adverse conditions.

Plus One Botany Notes Chapter 1 Biological Classification

Protozoans:
They are heterotrophs and live as predators or parasites.
Type of protozoans:
1. Amoeboid protozoans:

  • They live in freshwater or sea water
  • They capture their prey by pseudopodia (false feet) as in Amoeba.
  • Some are parasites as in Entamoeba

2. Flagellated protozoans:

  • They possesss flagella.
  • The parasitic forms cause diseases such as sleeping sickness. Example: Trypanosoma.

3. Ciliated protozoans:

  • They are aquatic and have a cavity (gullet) that collect food from outside.
  • They move with the help of cilia. Example: Paramoecium.

4 Sporozoans:
They are infectious due to the spore-like stage in their life cycle. eg: Plasmodium (malarial parasite) which causes malaria.
Plus One Botany Notes Chapter 1 Biological Classification 5

Kingdom Fungi:
They are heteterotrophs, mainly 2 types

  1. Saprophytes: They can absorb soluble organic matter from dead substrates
  2. Parasites: They are depend on living plants and animals

Symbiotic associations:

  1. Lichens-Fungi forms an association with algae
  2. Mycorrhiza-Fungi forms association with roots of higher plants.

Disease caused bv fungi:
They cause diseases in plants and animals. eg: wheat rust disease by Puccinia.

Salient features:

  • Yeast is unicellular fungus but others are multicellular.
  • Mycelium: lt is body of fungi contains many hyphae
  • Hyphae It is the long, slender thread-like structures
  • Some hyphae with multinucleated cytoplasm are called coenocytic hyphae.
  • Others have septae or cross walls in their hyphae. eg: Penicillium.
  • The cell walls of fungi are composed of chitin and polysaccharides

Types of Reproduction:

  1. Vegetative method: It takesplace by fragmentation, fission and budding.
  2. Asexual method: It takesplace by spores called conidia orsporangiospores or zoospores.
  3. Sexual reproduction: It takesplace by oospores, ascospores and basidiospores.
  4. The spores are produced in special structures called fruiting bodies.

Steps of sexual cycle:

(i) Fusion of protoplasms between two motile or non-motile gametes called plasmogamy.
(ii) Fusion of two nuclei called karyogamy.
(iii) Meiosis in zygote resulting in haploid spores

Plus One Botany Notes Chapter 1 Biological Classification 6

In this, two haploid hyphae come together and fuse results in diploid cells (2n).

Dikarvotic stage in funai:

  1. In ascomycetes and basidiomycetes, after plasmogamy dikaryotic stage (n + n ) occurs for some time. Later these nuclei fuse and the cells become diploid.
  2. The fungi form fruiting bodies in which reduction division occurs and forms haploid spores.

Plus One Botany Notes Chapter 1 Biological Classification

Phvcomycetes:
Salient features:

  • They are found in aquatic habitats and on decaying wood.
  • Their mycelium is aseptate and coenocytic.

Types of reproduction:
1 Asexual reproduction:
It takes place by zoospores (motile) or by aplanospores (non-motile). These spores are produced in sporangium.

2 Sexual reproduction:
It is the fusion of gametes have similar structure (isogamous) or dissimilar structure (anisogamous or oogamous) and after fusion zygospore is formed. Examples are Mucor, Rhizopus (the bread mould) and Albugo (the parasitic fungi on mustard).

Ascomycetes:
Salient features:

  • They are commonly known as sac-fungi, eg-unicellular- yeast (Sacharomyces) or multicellular Penicillium.
  • Some are coprophilous (growing on dung).
  • Mycelium is branched and septate.
  • The asexual spores are conidia produced on conidiophores.
  • Sexual spores are called ascospores which are produced in sac like ascus.
  • Spores are arranged in fruiting bodies called ascocarps.
  • Examples are Aspergillus, Claviceps and Neurospora.

Economic value:

  • Neurospora is used in genetic studies.
  • Edible members are morels and buffles.

Basidiomycetes:
Salient features:

  • Their mycelium is branched and septate.
  • Some members grow as parasites and disease causing organisms e.g. rusts and smuts
  • Common basidiomycetes are mushrooms, bracket fungi or puffballs

Reproduction:

  1. The asexual spores and sex organs are not found but vegetative reproduction by fragmentation.
  2. In sexual reproduction, plasmogamy occur by fusion of two vegetative cells of different strains. It results dikaryotic mycelia which gives rise to basidium. Later, karyogamy and meiosis takeplace in the basidium and producing four basidiospores.
  3. The basidia are arranged in fruiting bodies called basidiocarps.
  4. Examples -Agaricus (mushroom) Ustilago (smut) and Puccinia (rust fungus).

Plus One Botany Notes Chapter 1 Biological Classification

Deuteromvcetes:
Salient features:

  • They are called as imperfect fungi because perfect stage or sexual reproduction is absent.
  • Their asexual reproduction takes place with the help of conidia. ,
  • The mycelium is septate and branched.

Economic value:

  • Some members are decomposers play an important role in the mineral cycling.
  • Examples are Alternaria, Colletotrichum and Trichoderma.

kingdom Plantae

  1. Majority members are eukaryotic, chlorophyll-containing organisms.
  2. Few members are partially heterotrophic- insectivorous plants or parasite. eg: Bladder wort and Venus fly trap are examples of insectivorous plants and Cuscuta is a parasite.

Different types of plant group:
The kingdom Plantae includes algae, bryophytes, pteridophytes, gymnosperms and angiosperms.

Life cycle:
It has two distinct phases – the diploid sporophytic and the haploid gametophytic – that alternate with each other.

Kingdom Animalia:
Salient features:

  • It includes heterotrophic eukaryotic organisms.
  • They are multicellular and their cells lack cell wall.
  • Their mode of nutrition is holozoic (ingestion of food).
  • Most of them are capable of locomotion.

Viruses, Viroids And Lichens:
R.H. Whittaker not placed acellular organisms such as viruses, viroids and lichens in five kingdom classification.

VIRUSES:
Historical aspects and Discovery

  1. Name virus that means venom or poisonous fluid was given by Pasteur D.J. Ivanowsky.
  2. Extract of the infected plants of tobacco could cause infection in healthy plants and called the fluid as Contagium vivum fluidum (infectious living fluid).It was identified by M.W. Beijerinek (1898)
  3. Viruses could be crystallised and crystals consist of proteins outside. It was identified by W.M. Stanley. (1935)

Salient features:

  • Viruses are non living particle outside the living cell.
  • It has an inert crystalline structure .
  • They have living state inside the host and multiply by using host cell machinery-Ribosome. So they are called as obligate parasites.
  • They are smaller than bacteria because they passed through bacteria-proof filters.

Plus One Botany Notes Chapter 1 Biological Classification

Structure of viruses:
Viruses contain proteins coat outside, either RNA or DNA inside, (i.e either single or double stranded RNA or double stranded DNA).

The Protein coat called capsid made of small submits called capsomeres, protects the nucleic acid.

Symptoms and disease caused by viruses:
Disease:
Mumps, smallpox, herpes, influenza and AIDS
Symptoms in plants:

Mosaic formation, leaf rolling and curling, yellowing and vein clearing, dwarfing and stunted growth.

Viroids:
Strucure:
It has free RNA without protein coat.

Discovery:
T .O .Diener found that this infectious agent was smaller than viruses.

Disease:
It causes potato spindle tuber disease

Lichens:
They are symbiotic associations between algae and fungi.

Types of component:

  1. The algal component is called phycobiont: (autotrophic) prepare food for fungi
  2. The fungal component is called mycobiont: (heterotrophic) provide shelter and absorb mineral nutrients and water for algae.

Significance:
Lichens are very good pollution indicators i.e they do not grow in polluted areas.
Plus One Botany Notes Chapter 1 Biological Classification 7

Plus One Botany Notes Chapter 1 Biological Classification

Ncert Supplementary Syllabus
Six kingdom classification:
It was proposed by Carl Woese. It includes kingdoms like Archaebacteria, Eubacteria Protista, Mycota, Plantae and Animalia.

 

Plus One Zoology Notes Chapter 4 Biomolecules

Students can Download Chapter 4 Biomolecules Notes, Plus One Zoology Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Zoology Notes Chapter 4 Biomolecules

Plus One Zoology Notes Chapter 4 Biomolecules

How To Analyse Chemical Composition?
Take any living tissue (a vegetable or a piece of liver, etc.) and grind it in trichloroacetic acid (Cl3CCOOH) using a mortar and a pestle. The thick slurry is formed. Then it is passed through a cheese cloth or cotton getting two fractions.

  1. Acid soluble fraction (Filtrate)
  2. Acid-insoluble fraction.
    • All the carbon compounds from living tissues are called ‘biomolecules’.
    • The tissue is fully burnt, all the carbon compounds are oxidised to gaseous form (C02, water vapour) and are removed.
    • The remaining is called ‘ash’. It contains inorganic elements (like calcium, magnesium etc).
    • Inorganic compounds like sulphate, phosphate, etc., are also seen in the acid-soluble fraction.

Plus One Zoology Notes Chapter 4 Biomolecules 1
Organic compounds under biological view are classified into

  • Amino acids:
  • Nucleotide bases
  • Fatty acids etc.

Amino acids:

  1. They are organic compounds containing four substituent groups occupying the four valency positions.
  2. These are hydrogen, carboxyl group, amino group and a variable group designated as R group.

Plus One Zoology Notes Chapter 4 Biomolecules 2
Plus One Zoology Notes Chapter 4 Biomolecules

Based on the nature of R group there are many amino acids. However, those which occur in proteins are only of twenty one types.
The R group may be

  • Hydrogen (the amino acid is called glycine)
  • A methyl group (alanine)
  • Hydroxyl methyl (serine), etc.

Based on number of amino and carboxyl groups, there are

1. Acidic (eg: glutamic acid)
2. Basic (lysine) and neutral (valine) amino acids
3. Aromatic amino acids (tyrosine, phenylalanine, tryptophan)

A particular property of amino acids is due to ionizable nature of —NH2 and —COOH groups

Fatty acid:
It has a carboxyl group attached to an R group.
The R group could be

  1. A methyl (—CH2)
  2. Ethyl (—C2H5)

Carbon number varies in different fatty acids:

  • Palmitic acid – 16 carbon atoms
  • Arachidonic acid – 20 carbon atoms

Fatty acids are

1. saturated (without double bond)
2. unsaturated (with one or more C = C double bonds)
  • Lipids possess both glycerol and fatty acids.
  • They are monoglycerides, or diglycerides or triglycerides.
  • These are also called fats and oils based on melting point. Oils have lower melting point eg: gingely oil.
  • Some lipids have phosphorous, they are called phospholipids. They are found in cell membrane. eg: lecithin

Nitrogen bases:

  • They are (heterocyclic rings) adenine, guanine, cytosine, uracil, and thymine
  • If they are found attached to a sugar, they are called nucleosides.
  • If a phosphate group is found esterified to the sugar, they are called nucleotides.
  • Nucleic acids like DNA and RNA consist of nucleotides only.
Adenosine, guanosine, thymidine, uridine and cytidine are nucleosides.
Adenylic acid, thymidylic acid, guanylic acid, uridylic acid and cytidylic acid are nucleotides.

Diagrammatic representation of small molecular weight organic compounds in living tissues.
Plus One Zoology Notes Chapter 4 Biomolecules 3

Plus One Zoology Notes Chapter 4 Biomolecules

Primary And Secondary Metabolites:
Primary metabolites:
Organic compounds such as amino acids, sugars, etc.are belongs to primary metabolites. Primary metabolites play important role in normal physiologial processes.

Secondary metabolites:
When analyse plant, fungal and microbial cells the alkaloides, flavonoides, rubber, essential oils, antibiotics, coloured pigments, scents, gums, spices etc are found. These are called secondary metabolites. Many of them are useful to ‘human welfare’ (eg: rubber, drugs, spices, scents and pigments).

Pigments Carotenoids, Ant.hocyanins, etc.
Alkaloids Morphine, Codeine, etc.
Terpenoides Monoterpenes, Diterpenes etc.
Essential oils Lemon grass oil, etc.
Toxins Abrin, Ricin
Lectins Concanavalin A
Drugs Vinblastin, curcumin, etc.
Polymeric substances Rubber, gums, cellulose

Biomacromolecules:
The acid insoluble fraction, has only four types of organic compounds i.e., proteins, nucleic acids, polysaccharides and lipids. These compounds, except lipids, have molecularweights in the range often thousand daltons and above.

Lipids, whose molecularweights do not exceed 800 Da, come under acid insoluble fraction. Hence Lipids are not macromolecules.

Biomicromolecules and biomacromolecules:
Molecular weights less than one thousand dalton are referred to as micromolecules or simply biomolecules while those which are found in the acid insoluble fraction are called macromolecules or biomacromolecules.

Component % of the total cellular mass
Water 70 – 90
Proteins 10 – 15
Carbohydrates 3
Lipids 2
Nucleie acid 5 – 7
Ions 1

Plus One Zoology Notes Chapter 4 Biomolecules

Proteins:
Proteins (heteropolymer)are linear chains of amino acids linked by peptide bonds i.e polymer of amino acids There are 21 types of amino acids (eg: alanine, cysteine, proline, tryptophan, lysine, etc.)
Some Proteins and their Function:

  • Dietary proteins are the source of essential amino acids.
  • Therefore, amino acids are essential or non-essential.
  • Essential amino acids obtained through food.

Proteins carry out many functions in living organisms:

  1. some transport nutrients across cell membrane
  2. some fight infectious organisms
  3. Collagen is the most abundant protein in animal world and
  4. Ribulose bisphosphate Carboxylase – Oxygenase (RUBISCO) is the most abundant protein in the biosphere.
Protein Functions
Collagen Intercellular ground substance
Trypsin Enzyme
Insulin Hormone
Antibody Fights infectious agents
Receptor Sensory reception (smell, taste, hormone, etc.)
GLUT-4 Enables glucose transport into cells

POLYSACCHARIDES
1. Polysaccharides are long chains of sugars.

2. Forexamplecellulose(homopolymer)is a polysaccharide consist of only one type of monosaccharide i.e. glucose.

3. Starch is store house of energy in plant tissues but animals have glycogen as energy source.

4. Inulin is a polymer of fructose.

Plus One Zoology Notes Chapter 4 Biomolecules 4

5. In a polysaccharide eg glycogen, the right end is called the reducing end and the left end is called the non reducing end.

Starch forms helical secondary structures:

  1. Starch can hold l2 molecules in the helical portion. This reaction product blue in colour.
  2. Cellulose does not contain complex helices and hence cannot hold l2.
  3. Cotton fibre is cellulose
  4. The complex polysaccharides have as building blocks such as amino-sugars (eg: glucosamine, N— acetyl galactosamine, etc.).
  5. Exoskeletons of arthropods have a complex polysaccharide called chitin (heteropolymers)

Plus One Zoology Notes Chapter 4 Biomolecules

Nucleic Acids:
Nucleic acids are the another macromolecule that found in the acid insoluble fraction of living tissues. For nucleic acids, the building block is a nucleotide.

Components of nucleic acid:

  1. Heterocyclic compound(adenine, guanine, uracil, cytosine and thymine).
  2. Monosaccharide and
  3. A phosphoric acid or phosphate.

The sugar found in polynucleotides is either ribose (a monosaccharide pentose) or 2’ deoxyribose.

Nature of pentose sugar in DNA and RNA:
A nucleic acid containing deoxyribose is called deoxyribonucleic acid (DNA) while that which contains ribose is called ribonucleic acid (RNA).

Structure Of Proteins (Proteins are heteropolymers containing many amino acids):
Primary structure:
The sequence of amino acid in which the left end represented by the first amino acid (N— terminal amino acid )the right end represented by the last amino acid (C— terminal amino acid). This sequence forms linear structure. It is called the primary structure.
Plus One Zoology Notes Chapter 4 Biomolecules 5
Primary structure of a portion of a hypothetical protein. N and C refer to the two termini of every protein. Single letter codes and three letter abbreviations for amino acids are also indicated.

Secondary structure:
The primary structure have rigid rod like appearance which is folded in the form of a helix (similar to a revolving staircase). It appears as right handed helices. It is called the secondary structure. Secondary structures exhibited by DNA is the Watson-Crick model. In this DNA exists as a double helix.

Tertiary structure:
The long protein chain is also folded upon itself like a hollow wollen ball, it called the tertiary structure. This gives us a 3-dimensional view of a protein. Tertiary structure is necessary for the many biological activities of proteins.
Plus One Zoology Notes Chapter 4 Biomolecules 6

Plus One Zoology Notes Chapter 4 Biomolecules

Quaternary structure:
Some proteins are assembled by more than one polypeptide chains .This is called the quaternary structure Adult human haemoglobin consists of 4 subunits. Two of these are identical to each other. Hence, two subunits are of a type and two subunits are of p type together constitute the human haemoglobin (Hb).

Nature Of bond linking Monomers In A Polymer:
1. Peptide bond:
In a protein, amino acids are linked by a peptide bond which is formed when the carboxyl (—COOH) group of one amino acid reacts with the amino (-NH2) group of the next amino acid with the elimination of a water.

2. Glvcosidic bond:
In a polysaccharide the individual monosaccharides are linked by a glycosidic bond. This bond is also formed by dehydration.
Plus One Zoology Notes Chapter 4 Biomolecules 7

3. Phosphodiester Bond:
In a nucleic acid a phosphate moiety links the 3′-carbon of one sugar of one nucleotide to the 5′-carbon of the sugar of the succeeding nucleotide. The bond between the phosphate and hydroxyl group of sugar is called phosphodiester bond

DNA Structure:

  1. The two strands of polynucleotides are antiparallel i.e., run in the opposite direction.
  2. The backbone is formed by the sugar-phosphate-sugar chain.
  3. The nitrogen bases are A and G of one strand base pairs with T and C, respectively
  4. There are two hydrogen bonds between A and T but three hydrogen bonds are present between G and C.
  5. Each strand appears like a helical staircase.
  6. At each step of ascent, the strand turns 36°.
  7. One full turn of the helical strand have ten steps or ten base pairs.
  8. The pitch is 34A°. The distance between each base pairs is 3.4A°.
  9. This form of DNA is called B-DNA.

Dynamic State Of Body Constituents – Concept Of Metabolism:
Biomolecules are constantly being changed into some other biomolecules and also made from some other biomolecules. This is called turn over. This breaking and making is through chemical reactions constantly occurring in living organisms called as metabolism.

Metabolic reactions and transformation of biomolecules:

  1. removal of CO2 from amino acids making an amino acid into an amine,
  2. removal of amino group in a nucleotide base and
  3. hydrolysis of a glycosidic bond in a disaccharide
    • Majority of these metabolic reactions are always linked to some other reactions. This series of linked reactions called metabolic pathways.
    • These metabolic pathways are similar to the automobile traffic in a city.
    • Another feature of these metabolic reactions is that every chemical reaction is a catalysed reaction.
    • The catalysts which hasten the rate of a given metabolic conversation are also proteins. These proteins with catalytic power are named enzymes.

Plus One Zoology Notes Chapter 4 Biomolecules

Metabolic Basis For Living:

  1. Metabolic pathways involves two processes The synthesis step is called anabolic pathways. The degradation step is called catabolic pathways.
  2. Catabolic pathways lead to the release of energy.
  3. For example, when glucose is degraded to lactic acid in our skeletal muscle, energy is liberated which stored in the form of chemical bonds, when needed, this bond energy is utilized.

Which is the energy currency of a cell?

  • The energy currency in living systems is the bond energy in a chemical called adenosine triphosphate (ATP).

The Living State:

  • All living organisms exist in a steady-state characterised by concentrations of each of these biomolecules.
  • These biomolecules are in a metabolic flux. Any chemical or physical process moves spontaneously to equilibrium.
  • The steady state is a non-equilibirium state. The systems at equilibrium cannot perform work. As living organisms work continuously, they cannot afford to reach equilibrium.
Hence the living state is a non-equilibrium steady-state to be able to perform work.

Metabolism provides a mechanism for the production of energy. Hence the living state and metabolism are synonymous. Without metabolism there cannot be a living state.

Enzymes:

Almost all enzymes are proteins. Some nucleic acids that behave like enzymes are called ribozymes

Enzvme activity:

  • The tertiary structure is biologically active, an active site of an enzyme is a crevice or pocket into which the substrate fits.
  • Thus enzymes, through their active site, catalyse reactions at a high rate.
  • Enzymes are damaged at high temperatures (say above 40°C).
  • Some enzymes isolated from organisms who normally live under extremely high temperatures (eg: hot vents and sulphur springs), are stable and retain their catalytic power even at high temperatures (upto 80° – 90°C).
  • Thermal stability is thus an important quality of such enzymes isolated from thermophilic organisms.

Plus One Zoology Notes Chapter 4 Biomolecules

Chemical Reactions:
Chemical compounds undergo two types of changes.
1. Physical change:
It involves the change in shape without breaking of bonds. eg: when ice melts into water, or when water becomes a vapour.

2. Chemical reaction/change:
When bonds are broken and new bonds are formed during transformation, this will be called a chemical reaction.Eg. Hydrolysis of starch into glucose is an organic chemical reaction. Rate of a physical or chemical process refers to the amount of product formed per unit time.

Role of enzvme in the rate of chemical reaction:
In the absence of any enzyme this reaction is very slow, with about 200 molecules of H2CO3 being formed in an hour. But using an carbonic anhydrase, the reaction speeds dramatically with about 600,000 molecules being formed every second.

The enzyme has accelerated the reaction rate by about 10 million times. A multistep chemical reaction, when each of the steps is catalysed by the same enzyme complex or different enzymes, is called a metabolic pathway.

  1. In glycolysis glucose becomes pyruvic acid through ten different enzyme catalysed metabolic reactions.
  2. Under normal aerobic conditions, pyruvic acid is formed.
  3. In yeast, during fermentation, the same pathway leads to the production of ethanol (alcohol).
  4. In our skeletal muscle, under anaerobic conditions, lactic acid is formed.

How do Enzymes bring about High Rates of Chemical Conversions?
The chemical which is converted into a product is called a ‘substrate’. Hence enzymes, i.e. proteins with three dimensional structures including an ‘active site’ convert a substrate (S) into a product (P).

What is the transition state?
During the state where substrate is bound to the enzyme active site, a new structure of the substrate called unstable transition state is formed. Then the bond breaking/making is completed, the product is released from the active site. The y-axis represents the potential energy content.

The x-axis represents the progression of the structural transformation or states through the ‘transition state’. If ‘P’ is at a lower level than ‘S’, the reaction is an exothermic reaction one need not to supply energy (by heating) in order to form the product.

However, whether it is an exothermic or spontaneous reaction or an endothermic or energy requiring reaction, the ‘S’ has to go through a much higher energy state or transition state. The difference in average energy content of ‘S’ from that of this transition state is called ‘activation energy’.

Enzymes bring down energy barrier making the transition of ‘S’ to ‘P’ more easy. Catalysed reactions proceed at rates faster than that of uncatalysed ones.
Plus One Zoology Notes Chapter 4 Biomolecules 8

Plus One Zoology Notes Chapter 4 Biomolecules

Nature of Enzyme Action:
Plus One Zoology Notes Chapter 4 Biomolecules 9
Each enzyme (E) has a substrate (S) binding site in its molecule so that a highly reactive enzyme-substrate complex (ES) is produced. This complex is short-lived and dissociates into its products.

The catalytic cycle of an enzyme action can be described in the following steps:

1. First, the substrate binds to the active site of the enzyme.
2. The binding of the substrate induces the enzyme to alter its shape.
3. The active site of the enzyme, now in close proximity of the substrate breaks the chemical bonds of the substrate and the new enzyme- product complex is formed.
4. The enzyme releases the products of the reaction and the free enzyme is ready to bind to another molecule of the substrate.

Factors Affecting Enzyme Activity:
Plus One Zoology Notes Chapter 4 Biomolecules 10
The activity of an enzyme can be affected by temperature, pH, change in substrate concentration.
1. Temperature and pH:
Each enzyme shows its highest activity at a particular temperature and pH called the optimum temperature and optimum pH. Low temperature preserves the enzyme in a temporarily inactive state whereas high temperature destroys enzymatic activity because proteins are denatured by heat.

2. Concentration of Substrate:
With the increase in substrate concentration, the velocity of the enzymatic reaction rises at first. The reaction ultimately reaches a maximum velocity (Vmax) which is not increased by further rise in concentration of the substrate because the enzyme molecules are saturated there are no free enzyme molecules to bind with the additional substrate molecules

Enzyme inhibition:
When the binding of the chemical shuts off enzyme activity, the process is called inhibition and the chemical is called an inhibitor. When the inhibitor closely resembles the substrate in its molecular structure and inhibits the activity of the enzyme, it is known as competitive inhibitor. eg: Inhibition of succinic dehydrogenase by malonate which closely resembles the substrate succinate in structure. Such competitive inhibitors are often used in the control of bacterial pathogens.

Plus One Zoology Notes Chapter 4 Biomolecules

Classification and Nomenclature of Enzymes:
Enzymes are divided into 6 classes.
1. Oxidoreductases/dehvdroaenases:
Enzymes which catalyse oxidoreduction between two substrates S and S’ eg:
Plus One Zoology Notes Chapter 4 Biomolecules 11

2. Transferases:
Enzymes catalysing a transfer of a group, G (other than hydrogen) between a pair of substrate S and S’ eg:
\(\mathbf{S}-\mathbf{G}+\mathbf{S}^{‘} \longrightarrow \mathbf{S}+\mathbf{S}^{‘}-\mathbf{G}\)

3. Hydrolases:
Enzymes catalysing hydrolysis of ester, ether, peptide, glycosidic, C – C, C – halide or P – N bonds.

4. Lyases:
Enzymes that catalyse removal of groups from substrates by mechanisms other than hydrolysis leaving double bonds.
Plus One Zoology Notes Chapter 4 Biomolecules 12

5. Isomerases:
Includes all enzymes catalysing inter-conversion of optical, geometric or positional isomers.

6. Lyases:
Enzymes catalysing the linking together of 2 compounds, eg: enzymes which catalyse joining of C – O, C – S, C – N, P – O etc. bonds.

Co-factors:
Enzymes are composed of one or several polypeptide chains and non-protein constituents called cofactors. They are bound to the enzyme to make the enzyme catalytically active. The protein part of the enzymes is called the apoenzyme.
Three kinds of cofactors are

  1. prosthetic groups
  2. co-enzymes
  3. Metal ions.

1. Prosthetic groups:
They are organic compounds that are tightly bound to the apoenzyme. For example, in peroxidase and catalase, which catalyze the breakdown of hydrogen peroxide to water and oxygen. Haem is the prosthetic group and it is a part of the active site of the enzyme.

Plus One Zoology Notes Chapter 4 Biomolecules

2. Co-enzymes:
They are also organic compounds loosely bound to apoenzyme for catalysis. Co-enzymes serve as co-factors in a number of different enzyme-catalyzed reactions. Many coenzymes are vitamins eg: coenzyme nicotinamide adenine dinucleotide (NAD) and NADP contain the vitamin niacin.

2. Metations:
Zinc is a cofactor for the proteolytic enzyme carboxypeptidase. Catalytic activity is lost when the co-factor is removed from the enzyme.

Plus One Zoology Notes Chapter 11 Chemical Coordination and Integration

Students can Download Chapter 11 Chemical Coordination and Integration Notes, Plus One Zoology Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Zoology Notes Chapter 11 Chemical Coordination and Integration

What is neural system?
The neural system and the endocrine system coordinate and regulate the physiological functions in the body.

Plus One Zoology Notes Chapter 11 Chemical Coordination and Integration

Endocrine Glands And Hormones:
Endocrine glands lack ducts and are called ductless glands. Their secretions are called hormones.

Hormones are non-nutrient chemicals which act as intercellular messengers and are produced in trace amounts

Human Endocrine System
The endocrine glands are located in different parts of our body constitute the endocrine system. Pituitary, pineal, thyroid, adrenal, pancreas, parathyroid, thymus and gonads (testis in males and ovary in females) are the organised endocrine bodies in our body.

In addition to these, some other organs, eg: gastrointestinal tract, liver, kidney, heart also produce hormones.
Plus One Zoology Notes Chapter 11 Chemical Coordination and Integration 1

The Hypothalamus:
The hypothalamus is the basal part of diencephalon, forebrain and it regulates body functions. The hormones produced by hypothalamus are of two types

  1. The releasing hormones (which stimulate secretion of pituitary hormones)
  2. The inhibiting hormones (which inhibit secretions of pituitary hormones).

For example,

Hypothalamic hormone called Gonadotrophin releasing hormone (GnRH) stimulates the pituitary synthesis and release of gonadotrophins.
Somatostatin from the hypothalamus inhibits the release of growth hormone from the pituitary.

These hormones originating in the hypothlamic neurons, pass through axons and are released from their nerve endings reach the pituitary gland through a portal circulatory system and regulate the functions of the anterior pituitary. The posterior pituitary is under the direct neural regulation of the hypothalamus.
Plus One Zoology Notes Chapter 11 Chemical Coordination and Integration 2

Plus One Zoology Notes Chapter 11 Chemical Coordination and Integration

The Pituitary Gland:
The pituitary gland is located in a bony cavity called sella tursica. It is divided into an adenohypophysis and a neurohypophysis.

Adenohypophysis:
It consists of two portions, pars distalis and pars intermedia. The pars distalis region of pituitary, commonly called anterior pituitary, produces growth hormone (GH), prolactin (PRL), thyroid stimulating hormone (TSH), adrenocorticotrophic hormone (ACTH), luteinizing hormone (LH) and follicle stimulating hormone (FSH).

Pars intermedia secretes only one hormone called melanocyte stimulating hormone (MSH). Pars intermedia is almost merged with pars distalis.

Neurohvpophysis:
It is also known as posterior pituitary, stores and releases two hormones called

  1. Oxytocin
  2. vasopressin

Function:
These are synthesised by the hypothalamus and are transported to neurohypophysis.

Growth hormone:
Over-secretion of GH stimulates abnormal growth of the body leading to gigantism and low secretion of GH results in stunted growth resulting in pituitary dwarfism. Prolactin regulates the growth of the mammary glands and formation of milk in them.

TSH stimulates the synthesis arid secretion of thyroid hormones from the thyroid gland. ACTH stimulates the synthesis and secretion of steroid hormones called glucocorticoids from the adrenal cortex. LH and FSH stimulate gonadal activity and called as gonadotrophins.

Activity of LH and FSH in males and females:
In males, LH stimulates the synthesis and secretion of hormones called androgens from testis. In males, FSH and androgens regulate spermatogenesis. In females, LH induces ovulation of fully mature follicles (graafian follicles) and maintains the corpus luteum, formed from the graafian follicles after ovulation.

In females FSH stimulates growth and development of the ovarian follicles. MSH acts on the melanocytes (melanin containing cells) and regulates pigmentation of the skin. Oxytocin stimulates a vigorous contraction of uterus at the time of child birth, and milk ejection from the mammary gland.

Hormone in water reabsorption:
Vasopressin acts on kidney and stimulates resorption of water and electrolytes by the distal tubules and thereby reduces loss of water through urine (diuresis). Hence, it is also called as anti-diuretic hormone (ADH).

The Pineal Gland:
The pineal gland is located on the dorsal side of forebrain. It secretes a hormone called melatonin. It regulates 24-hour (diurnal) rhythm of our body. For example, it helps in maintaining sleep-wake cycle, body temperature, metabolism, pigmentation, the menstrual cycle as well as our defense capability.

Thyroid Gland:
It is composed of two lobes which are located on either side of the trachea. The thyroid gland is composed of follicles and stromal tissues. The follicular cells synthesise two hormones, tetraiodothyronine or thyroxine (T4) and triiodothyronine (T3). Deficiency of iodine in our diet results in hypothyroidism and enlargement of the thyroid gland called goitre.

Hypothyroidism during pregnancy causes defective development and maturation of the growing baby leading to stunted growth (cretinism), mental retardation, low intelligence quotient, abnormal skin, deaf-mutism, etc.

In adult women, hypothyroidism cause the occurrence of irregular menstrual cycle. Due to cancer of the thyroid gland the synthesis and secretion of the thyroid hormones is increased to abnormal high levels leading to a condition called hyperthyroidism.
Plus One Zoology Notes Chapter 11 Chemical Coordination and Integration 3

Plus One Zoology Notes Chapter 11 Chemical Coordination and Integration

Parathyroid Gland:
It is present on the back side of the thyroid gland and secrete a peptide hormone called parathyroid hormone (PTH).

Parathyroid hormone (PTH) increases the Ca2+ levels in the blood. It acts on bones and stimulates the process of bone resorption (dissolution/demineralisation).

PTH also stimulates reabsorption of Ca2+ by the renal tubules and increases Ca2+ absorption from the digested food. Hence PTH is a hypercalcemic hormone i.e., it increases the blood Ca2+ levels. Along with TCT, it plays a significant role in calcium balance in the body.

Thymus:
The thymus gland is located on the dorsal side of the heart and the aorta and plays a major role in the development of the immune system.

This gland secretes the peptide hormones called thymosins which is involved in the differentiation of T-lymphocytes and provides cell-mediated immunity.
Thymosins also promote production of antibodies to provide humoral immunity. Thymus is degenerated in old individuals and the immune responses of old persons become weak.

Adrenal Gland:
It is located at the anterior part of each kidney. The gland is composed of inner adrenal medulla, and outside the adrenal cortex.

Adrenal medulla:

It secretes two hormones called adrenaline or epinephrine and noradrenaline or norepinephrine. These are commonly called as catecholamines

Adrenaline and noradrenaline are secreted during emergency situations and are called emergency hormones or hormones of Fight or Flight. These hormones increase alertness, pupilary dilation, piloerection (raising of hairs), sweating, etc.

These hormones increase the heart beat, the strength of heart contraction and the rate of respiration. Catecholamines stimulate the breakdown of glycogen resulting in an increased concentration of glucose in blood. They also stimulate the breakdown of lipids and proteins.

Adrenal cortex:
It is divided into three layers, called

  1. zona reticularis (inner layer)
  2. zonafasciculata (middle layer)
  3. zona glomerulosa (outer layer).

The secretory hormones are commonly called as corticoids. They are involved in carbohydrate metabolism called as glucocorticoids. eg: Cortisol.
Plus One Zoology Notes Chapter 11 Chemical Coordination and Integration 4

Plus One Zoology Notes Chapter 11 Chemical Coordination and Integration

Function:
It maintains the cardio-vascular system as well as the kidney functions, suppresses the immune response and stimulates the RBC production. Corticoids, which regulate the balance of water and electrolytes in our body are called mineralocorticoids. eg: Aldosterone.

Glucocorticoids stimulate, gluconeogenesis, lipolysis and proteolysis and inhibit cellular uptake and utilisation of amino acids. Aldosterone stimulates the reabsorption of Na+ and water and excretion of K+ and phosphate ions.

Hence it helps in the maintenance of electrolytes, body fluid volume, osmotic pressure and blood pressure. Androgenic steroids secreted by the adrenal cortex which play a role in the growth of axial hair, pubic hair and facial hair during puberty.

Pancreas:
It acts as both exocrine and endocrine gland. The endocrine consists of ‘Islets of Langerhans’.

The two main types of cells in the Islet of Langerhans are called alpha cells and beta -cells. The alpha cells secrete a hormone called glucagon, while the beta cells secrete insulin

Glucagon is a peptide hormone maintains the normal blood glucose levels, stimulates glycogenolysis – increased blood sugar (hyperglycemia),stimulates the process of gluconeogenesis – contributes to hyperglycemia. Insulin is a peptide hormone, which enhances cellular glucose uptake and utilisation.

As a result, there is a rapid movement of glucose from blood to hepatocytes and adipocytes resulting in decreased blood glucose levels (hypoglycemia). Insulin also stimulates conversion of glucose to glycogen (glycogenesis) in the target cells.

Prolonged hyperglycemia leads to a complex disorder called diabetes mellitus which is associated with loss of glucose through urine and formation of harmful compounds known as ketone bodies.

Testis:
A pair of testis is present in the scrotal sac of male individuals Testis performs dual functions as a primary sex organ as well as an endocrine gland. Testis is composed of seminiferous tubules and stromal or interstitial tissue. The Leydig cells or interstitial cells, which produce a group of hormones called androgens mainly testosterone.

Androgens regulate the development, maturation and functions of the male accessory sex organs like epididymis, vas deferens, seminal vesicles, prostate gland, urethra etc.

Androgens also stimulate muscular growth, growth of facial and axillary hair, aggressiveness, low pitch of voice, spermatogenesis (formation of spermatozoa), influence the male sexual behaviour (libido).

These hormones produce anabolic (synthetic) effects on protein and carbohydrate metabolism.

Ovary:
It is the primary female sex organ which produces one ovum during each menstrual cycle. Ovary produces two groups of steroid hormones called estrogen and progesterone. The estrogen is are secreted by the growing ovarian follicles. After ovulation, the ruptured follicle is converted to a structure called corpus luteum, which secretes progesterone.

Estrogens involved in stimulation of growth and activities of female secondary sex organs, development of growing ovarian follicles, appearance of female secondary sex characters (e.g., high pitch of voice, etc.), mammary gland development, regulate female sexual behaviour.

Progesterone supports pregnancy, stimulates the formation of alveoli (sac-like structures which store milk) and milk secretion.

Plus One Zoology Notes Chapter 11 Chemical Coordination and Integration

Hormones Of Heart Kidney And Gastrointestinal Tract:
The atrial wall of our heart secretes a very important peptide hormone called atrial natriuretic factor (ANF), which decreases blood pressure. When blood pressure is increased, ANF is secreted which causes dilation of the blood vessels. This reduces the blood pressure.

The juxtaglomerular cells of kidney produce a peptide hormone called erythropoietin which stimulates erythropoiesis (formation of RBC). The gastro-intestinal tract secrete four major peptide hormones, namely gastrin, secretin, cholecystokinin (CCK) and gastric inhibitory peptide (GIP).

Gastrin stimulates the secretion of hydrochloric acid and pepsinogen. Secretin stimulates secretion of water and bicarbonate ions. CCK acts on both pancreas and gall bladder and stimulates the secretion of pancreatic enzymes and bile juice, respectively. GIP inhibits gastric secretion and motility.

Mechanism Of Hormone Action:
Hormones bind to specific proteins called hormone receptors Hormone receptors present on the cell membrane of the target cells are called membrane-bound receptors and the receptors present inside the target cell are called intracellular receptors.

Binding of a hormone to its receptor leads to the formation of a hormone-receptor complex. Hormone- Receptor complex formation leads to certain biochemical changes in the target tissue. On the basis of their chemical nature, hormones can be divided into groups.

  1. peptide,
  2. polypeptide,
  3. protein hormones (eg: insulin, glucagon, pituitary hormones, hypothalamic hormones, etc.)
    • steroids (eg: cortisol, testosterone, estradiol and progesterone)
    • iodothyronines (thyroid hormones)
    • amino-acid derivatives (eg: epinephrine).

Hormones which interact with membrane-bound receptors do not enter the target cell, but generate second messengers (eg: cyclic AMP, IP3, Ca++, etc) which in turn regulate cellular metabolism. Hormones which interact with intracellular receptors (eg: steroid hormones, iodothyronines, etc.) regulate gene expression or chromosome function.
Plus One Zoology Notes Chapter 11 Chemical Coordination and Integration 5
Plus One Zoology Notes Chapter 11 Chemical Coordination and Integration 6

Plus One Zoology Notes Chapter 11 Chemical Coordination and Integration

Exophthalmic goitre, also called Grave’s disease:
This occurs due to hyperthyroidism i.e the excessive secretion of thyroxine hormone is accompanied by the enlargement of the thyroid glands. It is an autoimmune disease where patients produce antibodies that act on the thyroid glands to increase thyroxine hormone production and thyroid size. eg: Patients suffering from cancerof thyroid glands.

The symptoms are elevated metabolic rate, sweating, rapid and irregular heartbeat, weight loss despite increased appetite, frequent bowel movement and nervousness. Some patients may also experience exophthalmos (or protrusion of the eyeballs). Thus this condition is also known as exophthalmic goitre.

Addison’s’ disease:
The hyposecretory disorder of the adrenal cortex or destruction of adrenal cortex in diseases such as tuberculosis leads to deficit of both glucocorticoids and mineralocorticoids. This condition is known as Addison’s disease. The symptoms are loose weight, their blood glucose and sodium levels drop and potassium levels rise.

NCERT SUPPLEMENTARY SYLLABUS
Exophthalmic goitre, also called Grave’s disease:
This occurs due to hyperthyroidism i.e the excessive secretion of thyroxine hormone is accompanied by the enlargement of the thyroid glands.

It is an autoimmune disease where patients produce antibodies that act on the thyroid glands to increase thyroxine hormone production and thyroid size. eg: Patients suffering from cancer of thyroid glands.

The symptoms are elevated metabolic rate, sweating, rapid and irregular heartbeat, weight loss despite increased appetite, frequent bowel movement and nervousness. Some patients may also experience exophthalmos (or protrusion of the eye balls). This condition is also known as exophthalmic goitre.

Addison’s’ disease:
The hyposecretory disorder of the adrenal cortex or destruction of adrenal cortex in diseases such as tuberculosis leads to deficit of both glucocorticoids and mineralocorticoids.

This condition is known as Addison’s disease. The symptoms are weight loss, blood glucose and sodium levels drop and potassium levels rise.

Plus One Accountancy Notes Chapter 12 Accounting System Using Database Management System

Students can Download Chapter 12 Accounting System Using Database Management System Notes, Plus One Accountancy Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus One Accountancy Notes Chapter 12 Accounting System Using Database Management System

Summary:
Accounting Reports:
A report displays information that is acquired from data processing and transformation in an organised manner. Reports tend to reduce the level of uncertainty associated with decision-makers and also influence their positive actions.

The output of the computerised accounting system are accounting reports. Financial accounting reports such as Cash book, Bank book, Ledger and Trial Balance may be generated in Access by adhering to report generation process.

Using Access for Producing Reports:
In Access, the reports are created by designing a report, identifying its information requirement, creating the queries in SQL to generate such information so that the final SQL statement provides the record set of information to the report design. Different Models of database design require different sets of SQL statements to produce different types of reports.

Plus One Accountancy Notes Chapter 12 Accounting System Using Database Management System

Queries Access:
There are several types of queries in Access that may be used to generate information. Such queries are called select queries because they are used to select records from the given set of records. There are three ways in which these queries may be created in Access: Wizard. Design View and SQL view method.

Designing Reports in Access:
A report in Access may be designed in three ways: Auto Report. Wizard and Design View method. An SQL statement (or query) is capable of displaying records containing fields from across a number of data tables.

A typical report in Access has the structure that consists of Report header, Page header, Group header, Details, Group footer, Page footer and Report footer.

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