You can Download Division for Growth and Reproduction Questions and Answers, Summary, Activity, Notes, Kerala Syllabus 9th Standard Biology Solutions Part 2 Chapter 7 help you to revise complete Syllabus and score more marks in your examinations.
Kerala State Syllabus 9th Standard Biology Solutions Chapter 8 Division for Growth and Reproduction
Division for Growth and Reproduction Textual Questions and Answers
The phase at which a cell prepares for division is called
………. takes place after karyokinesis
………… begins after interphase
What are changes that take place during interphase?
a) Division of nucleus (Karyokinesis)
b) Division of Cytoplasm (Cytokinesis)
State whether true or false
Cytokinesis takes place after karyokinesis
Main stages of cell division
Interphase, Division of nucleus, Division of cytoplasm
What are the important changes that take place during interphase?
- Number of cell organelles increase
- Quantity of cytoplasm increases
- Cell size increases
- Genetic material duplicate
A cell attains its complete growth during interphase. The fully grown cell undergoes division and becomes daughter cells. As the interphase and the division phase get repeated in a cyclic manner, they together constitute cell cycle.
…………..is brought about by cell division and cell growth
Growth of the body
What are the two types of cell division?
Mitosis and meiosis.
What do you mean by mitosis?
A parent cell divides to form two daughter cells are called mitosis.
Point out the phases taken place in the changes in nucleus?
Prophase, metaphase, anaphase and telophase
In which phase does the chromatin reticulum become chromosomes?
What changes occurs in telophase?
In telophase chromosomes that moved to the poles become chromatin reticulum and daughter nuclei are formed.
State whether true or false in prophase chromosomes become chromatin reticulum.
Complete the table of stages of nuclear division
|Prophase||1. Chromatin reticulum become chromosomes
2. Duplicated chromosomes.
3. Formation of spindle fibers
4. Nucleolus and nuclear membrane get disappeared
|Metaphase||Chromosomes have moved to the middle of the cell and, chromosomes doubled.|
|Anaphase||1. Chromatids are starting to separate from each other.
2. Formation of two sets of daughter chromosomes
|Telophase||1. Formation of daughter nuclei
2. Two daughter nuclei are formed.
3. There will be no change in chromosome number in each daughter nucleus
Cytokinesis (Division Of Cytoplasm)
The division of the cytoplasm is taken place in plant is entirely different. Give reason?
Because it is due to the presence of the cell wall in plant cell.
What is the significance of mitosis?
The significance of mitosis is that there is no change in the number of chromosomes.
Mitosis helps ………… & ……….
For the repair of tissues and growth.
Which condition leads to cancer?
Mitosis is a controlled process. A disruption in this controlled process leads to the excessive division of a cell and its proliferation. This condition leads to cancer.
Different Stages Of Growth
List out the different stages in the growth of human beings.
- Old age
What are the physical peculiarities of old age?
Rate of cell division decreases, Availability of oxygen to the cells decreases, Deterioration of cells increase Muscles shrink, Production of energy decrease
The elders should be cared. Do you agree with this statement? Why?
Old age is inevitable in life. The aged who worked for the welfare of their family and society during their younger age deserve special consideration.
What are the differences between the growth in plants and animals? Draw a comparison and complete table
|Animals grow only up to a certain stage Animals do not have localized centers of growth||Plants can grow throughout their lives Growth in plants is localized only at certain parts|
Plants grow due to the rapid division and differentiation of cells.
What do you mean by meristematic cells?
Meristematic cells are special types of cells that have the capacity for continuous division.
Plants can grow throughout their life due to the presence of
……… helps to increase the length of root and stem.
……… helps to increase the girth of the stem.
Name the meristematic cells which help to increase the length of the stem.
Where do you find intercalary meristem?
It seen above the nodes of monocot plants.
The stem of monocots increases in length faster than dicots. Why?
Because the intercalary meristem is visible only in the monocot plants.
Dicot plants: Lateral meristem
……………..: Intercalary meristem
The stem of monocots does not increase its girth beyond an extent. Why?
Because lateral meristem is absent in monocot plants.
Growth In Unicellular Organisms
Does cell division in unicellular organisms lead to growth or reproduction?
Mitosis leads to reproduction in unicellular organisms.
What do you mean by meiosis? Explain.
Meiosis is the mode of cell division in which gametes are formed. Meiosis occurs in the germinal cells of the reproductive organs. Human beings have 46 chromosomes. Germinal cells with 46 chromosomes divide continuously two times. These divisions in meiosis are known as meiosis I and meiosis II. Two daughter cells “with half the number of chromosomes (23 chromosomes) are formed in meiosis I. Each daughter cell again divides in meiosis II. There is no change in the chromosome number in this division. Hence meiosis II is similar to. mitosis. As a result of meiosis, four daughter cells, each with 23 chromosomes, are formed from a germinal cell.
What do you mean by polar body?
When meiosis occurs in the female germinal cell, a large ovum and three small cells are formed. The smaller cells are the polar bodies. These sterile cells get destroyed.
Complete the illustration
a = 46
b = 23
d = 23
e = 23
f = 23
g = 23
What is the number of chromosomes in germinal cells?
What is the number of chromosomes in the daughter cells formed after meiosis I?
What is the peculiarity of meiosis II?
Each daughter cell again divides in meiosis II. There is no change in the chromosome number in this division. Hence meiosis II is similar to mitosis.
What are the kinds of cell division occur in sexually reproducing organisms?
There are two kinds of cell division occur in sexually reproducing organisms that are mitosis and meiosis.
What are the different stages in the growth of human being?
Infancy, childhood, adolescence, youth and old age.
Differentiate mitosis and Meiosis
|Type of reproduction||Asexual||Sexual|
|Genetically Chromosome Number||Similar Remains same||Different Reduced by half|
|Takes place in||Somatic cells||Germ cells|
|Number of daughters||2 diploid||4 haploid|
Let Us Assess
The stage of karyokinesis at which daughter nuclei are formed
List the meristems in various parts of the plant and list their functions
|Apical meristem||Increase the length of root and stem|
|Lateral meristem||Helps to increases the girth of stem|
|Intercalary meristem||Helps to increase the length of the stem of monocot plants|
In females, only a single ovum is formed from a germinal cell, whereas in males, more than one sperm is formed. Give reason.
When meiosis occurs in the female germinal cell, a large ovum and three small cells are formed. The smaller cells are the polar bodies. These sterile cells get destroyed. So only a single ovum is formed from a germinal cell. But in males, after meiosis, four sperms having 23 chromosomes are formed form one germinal cell.
Observe the figures
a) Which stages of mitosis are indicated in the figures?
b) What are the changes that occur in the chromosomes during these stages?
b) Chromosomes get aligned at the equator of the cell.