Genotype	Dominant / recessive	Modification	Sex
mm	Homozygous recessive.	Restrict maleness	Female
Mlm	Heterozygous.	Induces maleness	Male
M2m	Heterozygous.	Induces both the sex	Bisexual (rare)
MIMI or  M2M2 or  MIM2	Homozygous / Heterozygous dominant.	Inviable plants	Sterile

Carica papaya, 2n = 36 (Papaya) has 17 pairs of auto somes and one pair of sex chromosomes. Male papaya plants have XY and female plants have XX. Unlike human sex chromosomes, papaya sex chromosomes look like auto somes and it is evolved from autosome. The sex chromosomes are functionally distinct because the Y chromosome carries the. genes for male organ development and X bears the female organ developmental genes. In papaya sex determination is controlled by three alleles. They are m, M, and M₂ of a single gene.

A = +                                     
D = Parasitism
B = Commensalism       
E = -

(i) Dr. Norman E. Borlaug.
(ii) Dr. M.S. Swaminathan.

S. No:	Prominent WLS in Tamil Nadu	Districts
i.	Vedanthangal Lake Birds WLS	Chengalpet
ii	Mudumalai WLS	Nilgiris
iii.	Point Calimere WLS	Nagapattinam

(i) Protecting soil quality using organic materials and encouraging biological activity.
(ii) Indirect provision of crop nutrients using soil microorganisms.
(iii) Nitrogen fixation in soils using legumes.
(iv) Weed and pest control based on methods like crop rotation, biological diversity, natural predators, organic manures and suitable chemical, thermal and biological interventions.

Germplasm Conservation
1. Germplasm conservation refers to the conservation of living genetic resources like pollen, seeds or tissue of plant material maintained for the purpose of selective plant breeding, preservation in live condition and used for many research works.
2. Germplasm conservation resources is a part of collection of seeds and pollen that are stored in seed or pollen banks, so as to maintain their viability and fertility for any later use such as hybridization and crop improvement.
3. Germplasm conservation may also involve a gene bank, DNA bank of elite breeding lines of plant resources for the maintenance of biological diversity and also for food security.

(i) The earliest fossils of the prehistoric man like Ramapithecus lived some 14mya. They were hairy and walked like gorillas and chimpanzees.
(ii) They had a brain capacity of 1300cc.
(iii) They lived on tough food consisting of seeds and savannah grasses and had well developed grains and heavy molars.
(iv) Australopithecus had a brain capacity of 461cc, teeth consisted of small canines and large molars. Good are softer foods consisting of grass, leaves and fruits.

1. Directly gametes cannot be transferred into the uterus, because the uterine environment is not suited for the survival of the gametes.
2. If the gametes directly transferred into the uterus, gametes will undergo degeneration (or) could be phagocytosed and viable zygotes will not be formed.
3. In this method, the own collected from a donor female is transferred to the fallopian tube of another woman.
4. The ovum has to be fertilized by the sperm of the woman's husband; the fallopian tube is the site for fertilization in a human female.
5. The gamete (ovum) if introduced into the uterus cannot move to the fallopian tube, the site of fertilization.

Relaxin  
(i) It is a hormone secreted by the placenta and also by the corpus luteum during pregnancy.
(ii) It promotes parturition by relaxing the pelvic joints and by dilation of cervical ligaments with continued powerful contractions.
Oxytocin:
(i) It causes the "Let-Down" reflex.
(ii) The actual ejection of milk from the alveoli of the mammary glands.
(iii) During lactation, oxytocin also stimulates the recently emptied uterus to contract, helping it to return to pre-pregnancy size..

The primary endosperm nucleus divides immediately after fertilization. It develops into an endosperm which is a nutritive tissue and a regulatory structure. The zygote divides only after that to form an embryo so that it can get nourishment from the endosperm that has formed earlier.

The crossing of two plants differing in two pairs of contrasting traits is called dihybrid cross. In a dihybrid cross, two characters (colour and shape) are considered at a time. Mendel considered the seed shape (round and wrinkled) and cotyledon colour (yellow & green) as the two characters. In seed shape round (R) is dominant over wrinkled (r); in cotyledon colour yellow (Y) is dominant over green (y). Hence the pure breeding round yellow parent is represented by the genotype RRYY and the pure breeding green wrinkled parent is represented by the genotype rryy. During gamete formation the paired genes of a character assort out independently of the other pair. During the F₁ x F₁ fertilization each zygote with an equal probability receives one of the four combinations from each parent. The resultant gametes thus will be genetically different and they are of the following four types:
1) Yellow round (YR)- 9/16
2) Yellow wrinkled (Yr)- 3/16
3) Green round (yR) - 3/16
4) Green wrinkled(yr) - 1/16
These four types of gametes of F₁ dihybrids unite randomly in the process of fertilization and produce sixteen types of individuals in F₂ in the ratio of 9 : 3 : 3 : 1 as shown in the figure. Mendel's 9:3:3:1 dihybrid ratio is an ideal ratio based on the probability including segregation, independent assortment and random fertilization. In sexually reproducing organism / plants from the garden peas to human beings, Mendel's findings laid the foundation for understanding inheritance and revolutionized the field of biology. The dihybrid cross and its result led Mendel to propose a second set of generalisations that we called Mendel's Law of independent assortment.

Competition: It is an interaction between two organisms or species in which both the organisms or species are harmed. Competition is the severest in population that has irregular distribution. Competition is classified into intraspecific and interspecific.
1. Intraspecific competition: It is an interaction between individuals of the same species. This competition is very severe because all the members of species have similar requirements of food, habitat and pollination etc., and they also have similar adaptations to fulfill their needs.
2. Interspecific competition: It is an interaction between individuals of different species. In grassland, many species of grasses grow well as there is little competition when enough nutrients and water is available. During drought shortage of water occurs. A life and death competition starts among the different species of grass lands. Survival in both these competitions is determined by the quantity of nutrients, availability of water and migration to new areas. Different species of herbivores, larvae and grass hopper competing for fodder or forage plants. Trees, shrubs and herbs in a forest struggle for sunlight, water and nutrients and also for pollination and dispersal of fruits and seeds. The Utricularia (Bladderwort) competes with tiny fishes for small crustaceans and insects.

Botanical pest repellent and insecticide made with the dried leaves of Azadirachta indica Preparation of Bio-pest repellent
(i) Pluck leaves from the neem tree and chop the leaves finely.
(ii) The chopped up leaves were put in a 50-liter container and fill to half with water; put the lid on and leave it for 3 days to brew.
(iii) Using another container, strain the mixture which has brewed for 3 days to remove the leaves, through fine mesh sieve. The filtrate can be sprayed on the plants to repel pests.
(iv) To make sure that the pest repellent sticks to the plants, add 100 ml of cooking oil and the same amount of soap water. (The role of the soap water is to break down the oil, and the role of the oil is to make it stick to the leaves).
(v) The stewed leaves from the mixture can be used in the compost heap or around the base of the plants.

i) The transfer RNA, (tRNA) molecule of a cell acts as a vehicle that picks up the amino acids scattered through the cytoplasm and also reads specific codes of mRNA molecules. Hence it is called an adapter molecule This term was postulated by Francis Crick.

(ii) The two dimensional clover leaf model of tRNA was proposed by Robert Holley. The secondary structure of tRNA depicted in the following picture looks like a clover leaf.
(iii) In actual structure, the tRNA is a compact molecule which looks like an inverted I.
(iv) The clover leaf model of tRNA shows the presence of three arms namely DHU arm, middle arm and TΨC arm.
(v) These arms have loops such as amino acyl binding loop, anticodon loop and ribosomal binding loop at their ends. In addition it also shows a small lump called variable loop or extra arm.
(vi) The amino acid is attached to one end (amino acid acceptor end) and the other end consists of three anticodon nucleotides.
(vii) The anticodon pairs with a codon in mRNA ensuring that the correct amino acid is incorporated into the growing polypeptide chain.
(viii) Four different regions of double-stranded RNA are formed during the folding process. Modified bases are especially common in tRNA.
(ix) Wobbling between anticodon and codon allows some tRNA molecules to read more than one codon.

Rain Water Harvesting - RWH (Solution to water crisis - A ecological problem)
Rainwater harvesting is the accumulation and storage of rainwater for reuse in-site rather than allowing it to run off.
Rainwater can be collected from rivers, rooftops and the water collected is directed to a deep pit.
The water percolates and gets stored in the pit.
RWH is a sustainable water management practice implemented not only in the urban area but also in agricultural fields, which is an important economic cost-effective method for the future.


Environmental benefits of Rain Water Harvesting:
(i) Promotes adequacy of underground water and water conservation.
(ii) Mitigates the effect of drought.
(iii) Reduces soil erosion as surface run-off is reduced.
(iv) Reduces flood hazards.
(v) Improves groundwater quality and water table / decreases salinity.
(vi) No land is wasted for storage purpose and no population displacement is involved.
(vii) Storing water underground is an eco- friendly measure and a part of sustainable water storage strategy for local communities.

Grassland ecosystem : There is a gradual decrease in the number of organisms in each trophic level from producers to primary consumers and then to secondary consumers, and finally to tertiary consumers. Therefore pyramids of number in grassland ecosystem are always upright.

Adaptation is a dynamic evolutionary process that fits organisms to their environment and enhancing their evolutionary fitness.
(a) Structural adaptations:
1. The external and internal structures of animals can help them to adapt better to their environment. Some of the most common examples are mammals growing thicker fur to survive freezing climates.
2. Some of the most attractive adaptations in nature occur for reasons of crypsis. (e.g: Camouflage) and mimicry.
3. Cryptic animals are those which camouflage perfectly with their environment and are almost impossible to detect. Certain reptiles and insects such as chameleons and stick insects show this type of adaptation, which helps in prey capture or to evade from predators. Likewise, horse legs are suitable for fast running and adapted for grasslands or plains and similar terrestrial environments.
(b) Behavioural adaptations:
1. Action and behaviour of animals are instinctive or learned. Animals develop certain behavioural traits or adaptations for survival.
2. Fleeing from a predator, hiding during sleep, seeking refuge from climate change or moving to find different food sources are all behavioural adaptations.
3. The two most characteristic forms of behavioural adaptations are migration and courtship.
4. Migration allows the animals to find better resources or evade threat.
5. Courtship is a set of behavioural patterns to find a made to reproduce.
6. Most nocturnal animals remain underground (or) inactive during daytime.
7. This is a modification of their feeding and activity pattern (or) habit (or) behaviour.
(c) Physiological adaptations:
1. The adaptations of organisms that help them to live and survive in their environment with unique niches.
2. Example: Lions have sharp canines to hunt and tear meat of preys and digestive system suitable for digesting raw meat.
3. The two most well-known physiological adaptations are hibernation and aestivation.
4. These are two different types of inactivity where the metabolic rate slows down so much that the animal can survive without eating or drinking.
5. Aquatic medium and terrestrial habitats have their own respective environmental conditions. Hence organisms have to evolve appropriate adaptations to select suitable habitats and niches.

1. In many species of fig trees, there is a one-to one relationship with the pollinator species of wasp. It means that a given fig species can be pollinated only by its 'partner' wasp species & no other species.
2. The female wasp uses the fruit not only as an oviposition (egg, laying) site but uses the developing seeds within the fruit for nourishing its larvae.
3. The wasp pollinates the fig inflorescence while searching for suitable egg-laying sites.
4. In return for the favour of pollination the fig offers the wasp, some of its developing seeds, as food for the developing wasp larvae.
5. The relationship that operates here is co-evolution.

(i) The production and development of seedless fruit is called parthenocarpy.
(ii) Fruit like structures may develop from the ovary without the act of fertilization. Such fruits are called parthenocarpic fruits
Examples: Seedless-Banana, Grapes, Papaya
(i) Parthenocarpy is of three types
1) Genetic Parthenocarpy
(i) Arises due to hybridization or mutation. 
2) Environmental Parthenocarpy
Environmental conditions like frost, fog, low or high temperature induce Parthenocarpy.
Example - low temperature for 3-19 hours induces parthenocarpy in Pear.
3) Chemically induced Parthenocarpy
(i) By the application of growth promoting hormones like auxins and gibberellins.
Significance:
(i) Seedless fruits - Significance in Horticulture have commercial value useful for the preparation of jarns, jellies, sauces, fruit drinks,
(ii) High proportion of edible part is available

a) Purine and pyrimidine bases are linked by hydrogen bonds.
b) Pentose sugar is linked to adjacent nucleotide by phosphodiester bonds.

Lymph nodes, spleen, tonsils, MALT

(a) Thalassemia
(b) Albinism
(c) sickle cell anaemia
(d) Huntington's chorea

Vivipary is a condition in which animals give rise to living young ones after being nourished in the uterus through the placenta. E.g. human

(i) Vigna radiata - Green gram.
(ii) Cajanus cajan - Red gram or pigeon pea.

The type of barrier that involves macrophages are the
(i) Phagocytic barriers which is a type of innate immunity.
(ii) In this mechanism, specialised cells such as monocytes, Neutrophils and tissue macro phages pha cytose and digest whole microorganisms.

(a) Trees provide micro climate for crops and maintain O₂ - CO₂ balance atmospheric temperature & relative humidity
(b) Suitable for dry land where rainfall is minimum hence it is a good system for alternate land use pattern

Because there is no effective light penetration & predominance of heterotrophs.

Placenta during pregnancy secretes hormones such as human chorionic gonadotrophic (hcG) estrogen, progesterone and human placenta lactogen. So, placenta is regarded as an endocrine tissue.