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Students can Download Chapter 11 Three Dimensional Geometry Notes, Plus Two Maths Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus Two Maths Notes Chapter 11 Three Dimensional Geometry

Introduction
To refer a point in space we require a third axis (say z-axis) which leads to the concept of three dimensional geometry. In this chapter we study the concept of direction cosines, direction ratios, equation of a line and a plane, angle between two lines and two planes, angle between a line and a plane, shortest distance between two skew lines, distance of a point from a plane.

Basic concepts
I. Direction cosines and direction ratios
Consider a directed line passing through the origin makes angles α, β, and γ with the positive
direction x-axis, y-axis, and z-axis. Then α, β, and γ are called direction angles. The cosine of α, β, and γ are called direction cosines. Generally cos α = l, cos β = m and cos γ = n . Any scalar multiple of direction cosines are called direction ratios.

1. If (a, b, c) is the coordinate of a point P then a,b,c is a direction ratio of the directed line passing along P and origin. Direction cosines will be

2. l² + m² + n² = 1

3. Direction ratios of a line segment passing through two points(x₁, y₁, z₁) and(x₂, y₂, z₂) is
x₂ – x₁, y₂ – y₁, z₁ – z₂

4. The angle between two lines having direction ratios a₁, b₁, c₁ and a₂, b₂, c₂ is

5. If direction ratios are proportional then the lines a, b, c, are parallel.ie; \(\frac{a_{1}}{a_{2}}=\frac{b_{1}}{b_{2}}=\frac{c_{1}}{c_{2}}\).

6. If a₁a₂ + b₁b₂ + c₁c₂ = 0 then the two lines are perpendicular.

II. Line in Space
Equation of line when a point and parallel direction ratios are given:
1. Vector equation:
\(\bar{r}=\bar{a}+\lambda \bar{b}\), where \(\bar{a}\) is a point, \(\bar{b}\) is a parallel vector and λ is a parameter, for different values of λ we get parallel lines.

2. Cartesian equation:

where (x₁, y₁, z₁) is a point and a, b, c is a parallel direction ratios.

Equation of line when two points are given:
1. Vector equation:
\(\bar{r}=\bar{a}+\lambda(\bar{b}-\bar{a})\), where \(\bar{a}\) and \(\bar{b}\) are points and λ is a parameter, for different values of λ we get parallel lines.

2. Cartesianequation:

where(x₁, y₁, z₁) and (x₂, y₂, z₂) are two points.

Angle between two lines:
1. Vector form:

be two lines and θ be the angle between them, then cosθ =

• If parallel \(\overline{b_{1}}=k \overline{b_{2}}\), k scalar.
• If perpendicular \(\overline{b_{1}} \overline{b_{2}}\) = 0.

2. Cartesian form:


be two lines and θ be the angle between them, then

• If parallel \(\frac{a_{1}}{a_{2}}=\frac{b_{1}}{b_{2}}=\frac{c_{1}}{c_{2}}\)
• If perpendicular a₁a₂ + b₁b₂ + c₁c₂ = 0.

Shortest distance between skew lines:
Lines which are neither interesting nor parallel are known as skew lines. Shortest distance between two skew lines is
1. Vector form:

be two skew lines, then d =

2. Cartesian form:

3. Distance between parallel lines,

III. Plane in space
Normal Form:
1. Vector Equation:
\(\bar{r}\).\(\hat{n}\) = d, where \(\hat{n}\) is a unit vector perpendicular to the Plane, and d is the perpendicular distance of the Plane from the origin. The general vector equation of a Plane is \(\bar{r} \bar{m}=d\), where \(\bar{m}\) is any vector perpendicular to the plane and cfis a constant.

2. Cartesian equation:
lx + my + nz = d, where l, m, n are direction cosines perpendicular to the Plane and dis the perpendicular distance of the Plane from the origin. The general cartesian equation of a Plane is ax + by + cz = d, where a, b, c are direction ratios perpendicular to the plane, and d is a constant.

Equation of plane when a point and a perpendicular vector is given:
1. Vector Equation:
\((\bar{r}-\bar{a}) \bar{m}=d\), where \(\bar{m}\) is a vector perpendicular to the Plane and \(\bar{a}\) is a point on the plane.

2. Cartesianequation:
a(x – x₁) + b(y – y₁) + c(z – z₁) = d, where a, b, c are direction ratios perpendicular to the plane and (x₁, y₁, z₁) is a point on the plane.

Equation of a plane passing through three non-collinear points:
1. Vector Equation:
\((\bar{r}-\bar{a}) \cdot[(\bar{b}-\bar{a}) \times(\bar{c}-\bar{a})]=0\), where \(\bar{a}, \bar{b}, \bar{c}\) are points on the plane.

2. Cartesian equation:

Where, (x₁, y₁, z₁), (x₂, y₂, z₂) and (x₃, y₃, z₃) are points on the plane.

3. Intercept form of the equation of a Plane:
Let a, b, c are the x-intercept, y-intercept and z- intercept made by a plane, then the equation of x y z such a Plane is \(\frac{x}{a}+\frac{y}{b}+\frac{z}{c}=1\).

4. Angle between two Planes:
Angle between two planes is same as the angle between there perpendicular vectors.

5. Vector Form:

be two Planes and θ be the angle between them, then cos θ

6.
(i) if parallel \(\overline{m_{1}}=k \overline{m_{2}}\), k scalar.
(ii) if perpendicular \(\bar{m}_{1} \overline{m_{2}}\) = 0

7. Cartesian form:
a₁x + b₁y + c₁z = d₁, a₂x + b₂y + c₂z = d₂ be two lines and θ be the angle between them, then

• If parallel \(\frac{a_{1}}{a_{2}}=\frac{b_{1}}{b_{2}}=\frac{c_{1}}{c_{2}}\)
• If perpendicular a₁a₂ + b₁b₂ + c₁c₂ = 0

Angle between a line and a Plane:

Plane passing through the intersection of two given planes:
The equation of family of Planes passing through the intersection of the Planes a₁x + b₁y + c₁z = d₁ and a₂x + b₂y + c₂z = d₂ is a₁x + b₁y + c₁z – d₁ + λ(a₂x + b₂y + c₂z – d) = 0.

Distance of a point from a Plane:
The perpendicular distance of the point (x₁, y₁, z₁) from a Plane ax + by + cz = d is

The distance between parallel Planes ax + by + cz = d₁ and ax + by + cz = d₂ is

Students can Download Chapter 1 Human Reproduction Notes, Plus Two Zoology Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus Two Zoology Notes Chapter 1 Human Reproduction

The Male Reproductive System
It consists of

Diagrammatic view of male reproductive system:

The testes are seen in a pouch called scrotum. It helps in maintaining the low temperature of the testes (2 – 2.5° C).

Each testis has about 250 compartments called testicular lobules. Each lobule contains one to three highly coiled seminiferous tubules in which sperms are produced.

Seminiferous tubule:
It consists of

The male germ cells produce sperm Sertoli cells provide nutrition to the germ cells. Leydig cells secrete testicular hormones called androgens:

Male sex accessory ducts:
It consists of
The seminiferous tubules of the testis open into rete testis

The vasa efferentia open into epididymis. The epididymis leads to vas deferens. It receives a duct from seminal vesicle and opens into urethra as the ejaculatory duct.

The urethra extends through the penis to its external opening called urethral meatus. The penis is the male external genitalia made up of special tissue that helps in erection of the penis to facilitate insemination.

The enlarged end of penis called the glans penis is covered by a loose fold of skin called foreskin.

Male accessory glands:
It consists of

Secretions of these glands constitute the seminal plasma (fructose, calcium and certain enzymes). The secretions of bulbourethral glands helps in the lubrication of the penis.

The Female Reproductive System
It consists of

1.  A pair of ovaries

2.  A pair of oviducts

3.  Uterus

4.  Cervix

5.  Vagina

6.  External genitalia

7.  Mammary glands

Digrammatic sectional view of female reproductive system:

Ovaries (primary female sex organ) produce the female gamete (ovum) and several steroid hormones (ovarian hormones).

Each ovary is about 2 to 4 cm in length and is connected to the pelvic wall and uterus by ligaments.

Female accessory ducts:
It consists of
The oviducts (fallopian tubes – 10 – 12 cm long)
uterus
vagina
Its parts

The funnel-shaped infundibulum. finger-like projections called fimbriae The wider part of the oviduct called ampulla. The last part of the oviduct isthmus joins the uterus.

The uterus opens into vagina through a narrow cervix. The cavity of the cervix is called cervical canal. The wall of the uterus has three layers of tissue.

1. External perimetrium
2. Middle myometrium and
3. Inner endometrium

The endometrium undergoes cyclical changes during menstrual cycle while the myometrium exhibits strong contraction during delivery of the baby.

Female external genitalia:
It consists of

1. Mons pubis (cushion of fatty tissue covered by skin and pubic hair)
2. Labia majora (fleshy folds of tissue extend down from the mons pubis and surround the vaginal opening)
3. Labia minora (paired folds of tissue under the labia majora)
4. Hymen (opening of the vagina is often covered partially by a membrane)
5. Clitoris (tiny finger-like structure which lies above the urethral opening)

The hymen is torn during the first coitus (intercourse). Mammary glands (paired structures (breasts)). 15-20 mammary lobes containing clusters of cells called alveoli. The cells of alveoli secrete milk, which is stored in the cavities of alveoli.

Alveoli -mammary duct- mammary ampulla- lactiferous duct through which milk is sucked out.

Gametogenesis
Spermatogenesis:

Some of the spermatogonia( diploid) called primary spermatocytes undergo meiosis. First meiotic division (reduction division) leading to formation of two equal haploid cells called secondary spermatocytes, second meiotic division produce four equal haploid spermatids.

The spermatids are transformed into spermatozoa (sperms) by the process called spermiogenesis.

After spermiogenesis, sperm heads become embedded in the Sertoli cells, and are finally released from the seminiferous tubules by the process called spermiation.
The GnRH stimulates secretion of two gonadotropins

1. Luteinising hormone (LH)
2. Follicle stimulating hormone (FSH).

LH acts at the Leydig cells and secrete androgens that stimulate the process of spermatogenesis. FSH acts on the Sertoli cells and stimulates secretion of some factors which help in the process of spermiogenesis.

Sperm:
Structure of sperm
It consists of

1.  Head

2.  Neck

3.  A middle piece and

4.  A tail

The sperm head is covered by a cap-like structure, acrosome (contains the enzymes that help fertilisation of the ovum).

The middle piece possesses numerous mitochondria, which produce energy for the sperm motility.

The human male ejaculates about 200 to 300 million sperms during a coitus of which 60 per cent sperms have normal shape and 40 per cent of show vigorous motility.

The Secretions of epididymis, vas deferens, seminal vesicle and prostate are essential for maturation and motility of sperms.

The seminal plasma with the sperms constitute the semen.

Oogenesis:
Oogonia are formed in embryonic stage udergores meiotic division to form primary oocytes. Primary oocyte then surrounded by a layer of granulosa cells and forms primary follicle.

During puberty 60,000-80,000 primary follicles are found in each ovary. The primary follicle is surrounded by more layers of granulosa and become secondary follicles.

Spermatogenesis

The secondary follicle become a tertiary follicle with fluid filled cavity called antrum. The primary oocyte within the tertiary follicle completes its first meiotic division( unequal division) and forms large haploid secondary oocyte and a tiny first polar body.

The tertiary follicle changes into the mature follicle or Graafian follicle.
Diagrammatic section view of ovary:

The secondary oocyte then forms a new membrane called zona pellucida surrounding it.

The Graafian follicle ruptures to release the secondary oocyte (ovum) from the ovary by the process called ovulation.

Menstrual Cycle
Diagrammatic representation of various events during a menstrual cycle:

1. The menstrual phase:
First menstruation begins at puberty and is called menarche. In human females it is repeated at interval of about 28/29 days.

The menstrual flow is due to the breakdown of endometrial lining of the uterus and its blood vessels which forms liquid that comes out through vagina.

Menstruation only occurs if the released ovum is not fertilised. Lack of menstruation may be indicative of pregnancy.

2. The follicular phase:
During this phase, the primary follicles grows into mature Graafian follicle and endometrium of uterus regenerates through proliferation.

3. The ovulatory phase:
Both LH and FSH attain a peak level in the middle of cycle (about 14th day).

4. The luteal phase:
Remaining parts of the Graafian follicle transform into corpus luteum. The corpus luteum secretes large amounts of progesterone which helps in the maintenance of the endometrium (implantation of the fertilized ovum).

In the absence of fertilisation, the corpus luteum degenerates. This causes disintegration of the endometrium leading to menstruation.In human beings, menstrual cycles ceases around 50 years of age termed as menopause.

Fertilisation And Implantation
During copulation (coitus) semen is released by the penis into the vagina (insemination).

The motile sperms reach the junction of the isthmus and ampulla (ampullary-isthmic junction) of the fallopian tube and fuses with the released ovum (fertilization) it results a diploid zygote.

Ovum surrounded by few sperms:

During fertilisation, a sperm comes in contact with the zona pellucida layer of the ovum and induces changes in the membrane that block the entry of additional sperms.

The secretions of the acrosome help the sperm enter into the cytoplasm of the ovum through the zona pellucida and the plasma membrane. This induces the completion of the meiotic division of the secondary oocyte and forms a second polar body and a haploid ovum (ootid).

All the haploid gametes produced by the female (ova) have the sex chromosome X whereas in the male gametes (sperms) the sex chromosome could be either X or Y, hence, 50 per cent of sperms carry the X chromosome while the other 50 per cent carry the Y.

The zygote carrying XX would develop into a female baby and XY would form a male. During fertilisation, a sperm comes in contact with the zona pellucida layer of the ovum and induces changes in the membrane that block the entry of additional sperms.

Transport of ovum, fertilisation and passage of growing embryo through fallopian tube:

The secretions of the acrosome help the sperm enter into the cytoplasm of the ovum through the zona pellucida and the plasma membrane. This induces the completion of the meiotic division of the secondary oocyte and forms a second polar body and a haploid ovum (ootid).

All the haploid gametes produced by the female (ova) have the sex chromosome X whereas in the male gametes (sperms) the sex chromosome could be either X orY, hence, 50 percent of sperms carry the X chromosome while the other 50 percent carry the Y.

The zygote carrying XX would develop into a female baby and XY would form a male. The mitotic division of zygote is called cleavage and forms 2, 4, 8, 16 daughter cells called blastomeres. The embryo with 8 to 16 blastomeres is called a morula. The morula continues to divide and transforms into blastocyst then it moves into the uterus.

The outer layer of blastocyst is called trophoblast and an inner group of cells called inner cell mass. The trophoblast layer gets attached to the endometrium and the inner cell mass gets differentiated as the embryo.

Later the blastocyst becomes embedded in the endometrium of the uterus. This is called implantation and it leads to pregnancy.

The milk produced during the initial few days of lactation is called colostrum which contains several antibodies provide resistance for the new-born babies.

Students can Download Chapter 3 Strategies for Enhancement in Food Production Notes, Plus Two Botany Notes helps you to revise the complete Kerala State Syllabus and score more marks in your examinations.

Kerala Plus Two Botany Notes Chapter 3 Strategies for Enhancement in Food Production

Animal Husbandry
It is the agricultural practice of breeding and raising livestock which deals with the care and breeding of livestock like buffaloes, cows, pigs, horses, cattle, sheep, camels, goats, etc., that are useful to humans.

It includes poultry farming and fisheries also. Fisheries include rearing, catching and selling offish, mollusks and crustaceans (prawns, crabs, etc.).

More than 70 per cent of the world livestock population is in India and China.

1. Management of Farms and Farm Animals:
The modem practices of farm management improves and enhances food production.

a. Dairy Farm Management:
It is the management of animals for milk and its products for human consumption. Diairyfarm management includes processes and systems that increase yield and improve quality of milk.
It includes

Selection of good breeds having high yielding potential, resistance to diseases, they have to be housed well, should have adequate water, maintained disease free, feeding should be in a scientific manner (in the quality and quantity of fodder), maintaining cleanliness and hygiene during milking, storage and transport of the milk and its products, and require regular visit of a veterinary doctor.

b. Poultry Farm Management:
It is the management of chicken, ducks, turkey and geese for food or their eggs.

As in dairy farming, selection of disease free breeds, proper and safe farm conditions, proper feed and water and hygiene and health care are important components of poultry farm management.

Recently, the spread of ‘bird flu virus’ affected the egg industy and chicken consumption. The causative virus is H5N1.

2. Animal Breeding:
It aims for increasing the yield of animals and improving the desirable qualities of the produce.
The term ‘breed’ refers to a group of animals related by descent and similar in general appearance, features, size, configuration, etc.

When breeding is between animals of the same breed it is called inbreeding, while crosses between different breeds are called outbreeding.

Inbreeding

It is the mating of more closely related individuals within the same breed for 4 – 6 generations. In this, superior males (the bull which gives rise to superior progeny) and superior females (cow or buffalo that produces more milk per lactation) of the same breed are mated.

The progenies are evaluated and superior among them are identified for further mating.

The strategy used for developing purelines in cattle is the same as Mendel was practiced. Thus inbreeding is necessary for evolving a pureline in any animal. Inbreeding increases homozygosity.

It exposes harmful recessive genes that are eliminated by selection. It also helps in the accumulation of superior genes and elimination of less desirable genes. But the continued inbreeding reduces fertility and productivity. This is called inbreeding depression.

It is overcome by mating with unrelated superior animals of the same breed. This is usually helps to
restore fertility and yield.

Out-breeding
It is the breeding of the unrelated animals of the same breed (but having no common ancestors), or between different breeds (cross-breeding) or different species (inter-specific hybridisation).

(A) Out-crossing:
It is mating of animals within the same breed, but having no common ancestors on either side of their pedigree up to 4-6 generations. The offspring produced called as out-cross. It is the method used for increasing milk production, growth rate in beef cattle, etc.

(B) Cross-breeding:
It is the method of mating superior males of one breed with superior females of another breed. The progeny hybrid animals are used for commercial production.
Eg-Hisardale is a new breed of sheep developed in Punjab by crossing Bikaneri ewes and Marino rams.

Eg-Hisardale is a new breed of sheep developed in Punjab by crossing Bikaneri ewes and Marino rams.

Interspecific hybridisation
It is the method of mating of male and female animals of different species, the progeny shows combined desirable features of both the parents with economic value, e.g., mule.
Mule:

Controlled breeding experiments are carried out using artificial insemination. The semen is collected from the male parent and injected into the reproductive tract of the selected female.

Semen can be stored in freezing state and used later. Artificial insemination helps to overcome several problems of normal matings.
To improve chances of successful production of hybrids, other technique is used.

Multiple Ovulation Embryo Transfer Technology (MOET)
In this method, a cow is given hormones, with FSH-like activity, to induce follicular maturation and super ovulation, it produce 6 – 8 eggs/cycle. This animal isthen mated with an elite bull or artificially inseminated. The fertilised eggs at 8 – 32 cells stages, are removed and transferred to surrogate mother.

The genetic mother is available for another round of super ovulation. This technology is useful for cattle, sheep, rabbits, buffaloes, mares, etc.

3. Bee-keeping
Bee-keeping or apiculture is an age-old cottage industry for the maintenance of hives of honeybees for the production of honey. Honey is a food of high nutritive value and used in medicine. Beeswax, obtained from them are used in the preparation of cosmetics and polishes. It is an income-generating industry.

Bee-keeping can be practiced in the area having wild shrubs, fruit orchards and cultivated crops grows.
The most common species used is Apis indica.
For successful bee-keeping it requires

(i) Knowledge of the nature and habits of bees, (ii) Selection of suitable location for keeping the beehives, (iii) Catching and hiving of swarms (group of bees), (iv) Management of beehives during different seasons, and (v) Handling and collection of honey and of bees wax.

Bees are the pollinators of many crop species such as sunflower, Brassica, apple and pear. Keeping beehives in crop fields during flowering period increases pollination efficiency and improves the crop yield and honey yield.

4. Fisheries
It is an industry for the catching, processing or selling offish, shellfish or other aquatic animals. Some of the freshwater fishes Catla, Rohu and common carp and the marine fishes Hilsa, Sardines, Mackerel and Pomfrets are commercially important.

Fisheries provides income and employment to millions of fishermen and farmers Aquaculture and pisciculture is used to increase the production of aquatic plants and animals Increasd production offish and their products are coming under blue Revolution’.

Plant Breeding
This technology aims to increase yields .Here Green Revolution plays an important role to meet the national requirements in food production .This is achieved through development of high-yielding and disease resistant varieties in wheat, rice, maize, etc.

1. What is Plant Breeding?
It is the purposeful manipulation of plant species to create desired plant types that are good for cultivation, better yields and disease resistant. Major food crops of today are developed from domesticated varieties that obtained from conventional plant breeding practices.

Today the crop improvement programme mainly based on genetics, molecular biology and tissue culture, Plant breeders give importance to crop yield and quality, increased tolerance to environmental stresses (salinity, extreme temperatures, drought), resistance to pathogens (viruses, fungi, and bacteria) and increased tolerance to insect pests.

Main steps of plant breeding for developing a new genetic variety of a crop are

(i) Collection of variability:
Genetic variability is mainly created from wild relatives of the crop. For this all wild varieties, species and relatives of the cultivated species are collected and preserved. The entire collection (of plants/seeds) having all the diverse alleles for all genes in a given crop is called germplasm collection.

(ii) Evaluation and selection of parents:
The selected plants with desirable combination of characters are multiplied and used in the process of hybridisation.

(iii) Cross hybridisation among the selected parents:
The desired characters from two different plants (parents) are combined and produce hybrids. One parent with high protein quality is combined with disease resistance of other parent. This is a very time-consuming and tedious process because the pollen grains from the male parent are collected and placed on the stigma of female parent.

(iv) Selection and testing of superior recombinants:
It is the testing of progeny that have the desired character combination. This step yields plants that are superiorto both of the parents.

(v) Testing, release and commercialisation of new cuttivars:
The newly selected progenies are evaluated for their yield, quality, disease resistance, etc. It is done by growing these plants in the research fields and recording their performance under ideal fertiliser application, irrigation, and other crop management practices.

The evaluation is followed by testing the materials in farmers fields, for at least three growing seasons at several locations in the country. These progenies are then evaluated in comparison to the best available local crop cultivar.

The agriculture contribution to India’s GDP is 33 percent and employs nearly 62 percent of the population. After India’s independence, the main challenge was to produce food for the increasing population. The development of several high yielding varieties of wheat and rice led to the dramatic increase in food production in our country. This is called as the Green Revolution.

Wheat and Rice

During the period 1960 to 2000, wheat production increased from 11 million tones to 75 million tonnes while rice production from 35 million tonnes to 89.5 million tonnes.

This was due to the development of semi-dwarf varieties of wheat and rice. Nobel laureate Norman E. Borlaug, at International Centre for Wheat and Maize had developed semi-dwarf wheat.

In 1963, high yielding and disease resistant wheat Sonalika and Kalyan Sona, were developed in India. Semi-dwarf rice varieties were developed from IR – 8 and Taichung Native-1. Later better-yielding semi dwarf varieties Jaya and Ratna were developed in India.

Sugarcane:
Saccharum barberi of north India had poor sugar content and yield. But Saccharum officinarumm of south India had thicker stems and higher sugar content but did not grow well in north India.

These two species are crossed to get sugar cane varieties combining the desirable qualities of high yield, thick stems, high sugar and ability to grow in the sugar cane areas of north India.

Millets:
The successfully developed millets in India are Hybrid maize, jowar and bajra. They are high yielding and resistant to water stress.

2. Plant Breeding for Disease Resistance:
Breeding of cultivars resistant to disease increases food production. It helps to reduce the dependence on the use of fungicides and bacteriocides. Before breeding, it is important to know about the causative organism and the mode of transmission.

Some of the diseases caused by fungi are rusts, e.g., brown rust of wheat, red rot of sugarcane and late blight of potato; by bacteria – black rot of crucifers; and by viruses – tobacco mosaic, turnip mosaic, etc.

Methods of breeding for disease resistance
It is done by the conventional breeding techniques (hybridisation and selection) or by mutation breeding. Conventional breeding is facing some difficulties because the limited number of disease resistant genes present in crop varieties orwild relatives.

These are either multiplied ordirectly used in breeding. Other breeding methods used are selection amongst somaclonal variants and genetic engineering.

Crop varieties resistant to bacteria, fungi and viruses

Mutation
It is the method of changing the base sequence within genes resulting in the creation of a new character not found in the parental type. It is done by inducing mutations artificially or by using chemicals or radiations (like gamma radiations), and selecting and using the plants that have the desirable character. This process is called mutation breeding.

Eg-In mung bean, resistance to yellow mosaic virus and powdery mildew were induced by mutations. Wild relatives of cultivated species have resistant characters but very low yield. So it is a need to introduce the resistant genes into the high-yielding cultivated varieties.

Eg- Gene resistant to yellow mosaic virus of wild species- bhindi (Abelmoschus esculentus) -transferred to the variety of A. esculentus and a new variety formed is called as Parbhani kranti.

3. Plant Breeding for Developing Resistance to Insect Pests:
Insect resistance in host crop plants can be developed in many ways particularly morphological, biochemical or physiological manner.

(1) Hairy leaves shows resistance to insect pests e.g, resistance to jassids in cotton and cereal leaf beetle in wheat (2) In wheat, solid stems resistant to stem sawfly and smooth leaved and nectar-less cotton varieties resistant bollworms. (3) High aspartic acid, low nitrogen and sugar content in maize shows resistance to maize stem borers.

The above insect resistance is made by hybridization techniques.
Crop varieties resistant to pest

4. Plant Breeding for Improved Food Quality:
In the world about three billion people suffer from micronutrient ( particularly iron, vitamin A, iodine and zinc), protein and vitamin deficiencies or ‘hidden hunger’. Diets lacking essential micronutrients increase the risk for disease, reduce lifespan and reduce mental abilities.

Biofortification
It is the breeding of crops with higher levels of vitamins minerals, proteins and healthier fats.

Objectives of improving nutritional quality (i) Protein content and quality; (ii) Oil content and quality; (iii) Vitamin content; and (iv) Micronutrient and mineral content.

1. Maize hybrids possess twice the amount of the amino acids (lysine and tryptophan).
2. Wheat variety, Atlas 66, with a high protein content,
3. Iron-fortified rice variety have five times iron content.

The Indian Agricultural Research Institute, New Delhi has also released several vegetable crops that are rich in vitamins and minerals.

1. Vitamin A-enriched carrots, spinach, pumpkin etc.
2. Vitamin C enriched bitter gourd,bathua, mustard, and tomato;
3. Iron and calcium enriched spinach and bathua;
4. Protein enriched beans – broad, lablab, French and garden peas.

Single Cell Protein (SCP):
More than 25 per cent of human population is suffering from hunger and malnutrition So the new alternate sources of proteins for animal and human nutrition is Single Cell Protein (SCP). Eg- Spirulina (source of good Protein).

Spirulina can grown on waste water from potato processing plants straw, molasses, animal mannure and even sewage to produce large quantities and food rich in protein, minerals, fats, carbohydrate and vitamins. This method of growing spirulina in waste waters reduces environmental pollution.

About 250 Kg cow produces 200 g of protein per day. But 250g of micro-organism like Methylophilus methylotrophus, expected to produce 25 tonnes of protein. Microbes like mushrooms are cultivated in large scale and it is an acceptable as food.

Tissue Culture
It is method in which plants are regenerated from explants. The capacity to generate a whole plant from any cell/explant is called totipotency.
Tissue culture medium

1. carbon source -sucrose
2. inorganic salts
3. vitamins
4. amino acids
5. growth regulators like auxins, cytokinins etc.

Micropropagation
It is the tissue culture method useful for the propagation of a large number of plants in very short durations.

All plants developed are genetically identical to the original plant, i.e., they are somaclones.
Many important food plants like tomato, banana, apple, etc. produced on commercial scale using this method.

Meristem culture
It is tissue culture method in which Healthy plants are developed from diseased plants or infected with a virus.

Here the meristem is taken from apical and axillary part and grow it in vitro to obtain virus-free plants Eg- banana, sugarcane, potato, etc.

Somatic hybridization
Here protoplast is isolated from plants by using enzymes. Isolated protoplasts from two different varieties of plants having desirable character are fused to get hybrid protoplasts, which can be further grown to form a new plant.

These hybrids are called somatic hybrids.
Eg- Protoplast of tomato is fused with that of potato and grown to form new hybrid plants containing the characters of tomato and potato. But here the desired combination of characters are not fully expressed for its commercial utilisation.