(a) Nilgiris (Tamil Nadu - Kerala)
(b) Agasthya malai (Tamil Nadu - Kerala - Karnataka)
(c) Gulf of Mannar (Tamil Nadu)

Normal chromosome of Drosophila melanogaster (2n)    = 8
Trisomic condition (2n+ 1)                                                = 9
Monosomic condition (2n-l)                                              =  7

Thermal stratification is usually found in aquatic habitat. The change in the temperature profile with increasing depth in a water body is called thermal stratification. There are three kinds of thermal stratifications.
1. Epilimnion - The upper layer of warmer water.
2. Metalimnion - The middle layer with a zone of gradual decrease in temperature.
3. Hypolimnion - The bottom layer of colder water.

In asexually propagated crop, progenies derived from a plant resemble in genetic constitution with the parent plant as they are mitotically divided. Based on their phenotypic appearance, clonal selection is employed to select improved variety from a mixed population (clones). The selected plants are multiplied through vegetative propagation to give rise to a clone. The genotype of a clone remains unchanged for a long period of time.

Gross Primary Productivity (GPP) is the total amount of food energy or biomass produced in an ecosystem by autotrophs through the process of photosynthesis whereas Net Primary Productivity (NPP) is the proportion of energy which remains after respiration loss in the plant. When we compare GPP with NPP more energy is present in former than in latter.

Characters of biome 
(i) Location, geographical position (Latitude, Longitude)
(ii) Climate and physiochemical environment
(iii) Predominant plant and animal life
(iv) Boundaries between biomes are not always sharply defined. Transition or transient zones are seen as in case of grassland and forest biomes.

(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.

Ramapithecus\(\rightarrow \) Austrolopithecus \(\rightarrow \) Homo habilis \(\rightarrow \)  Homo sapiens

1. Polyspermy: An egg that has been fertilized by more than one sperm
2. When a sperm comes in contact with the zona pellucida layer of the ovum, it induces changes in the membrane of the ovum to block the entry of additional sperms.
3. The prevention of polyspermy ensures that only one sperm can fertilize a single ovum.

ovule is divided into two types based on the position of the sporogenous cell

Tenuinucellate type	Crassinucellate type
Sporogenous cell is hypodermal with a single layer of nucellar tissue around it.	Sporogenous cell is sub hypodermal
Have very small nucellus	Have fairly large nucellus.

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.

(c) R explains A.

At the point of origin of replication, the helicases and topoisomerases (DNA gyrase) unwind and pull apart the strands, forming a Y-Shaped structure called the replication fork. There are two replication forks at each origin

Infectious disease	Non-infectious disease
Disease which are transmitted form one person to another are called infectious disease. e.g. Common cold	Disease which do not transmitted form one person to another are called non-infectious disease. e.g. Anaemia

The I gene exists in three forms: l^A, I^B and 1^O. The alleles are located on chromosome 9.

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

Inflorescence of palmyra is tapped for its sap which is used as health drink. Sap is processed to get palm jaggery or fermented to give toddy.

The immune responses may be primary or secondary.
(i) The primary immune response occurs when a pathogen comes in contact with the immune system for the first time.
(ii) The secondary immune response occurs when a person is exposed to the same antigen again. During this time, immunological memory has been established and the immune system can start producing antibodies immediately. Within hours after recognition of the antigen, a new army of plasma cells are generated. Within 2 to 3 days, the antibody concentration in the blood rises steeply to reach much higher level than primary response. This is also called as "booster response".

(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

1. Eurythermal: Organisms which can tolerate a wide range of temperature fluctuations.
2. Stenohaline: Organisms which can withstand only small range of salinity.
3. These variations the organisms also grow in different environment.

1. Avoid sex with unknown partner/multiple partner
2. Use condoms.
3. In case of doubt, consult a doctor for diagnosis and get complete treatment.

In prokaryotes, there are three major types of RNAs: mRNA, tRNA, and rRNA. All three RNAs are needed to synthesize a protein in a cell. The mRNA provides the template, tRNA brings amino acids and reads the genetic code, and rRNAs play structural and catalytic role during translation. There is a single DNA-dependent RNA polymerase that' catalyses transcription of all types of RNA. It binds to the promoter and initiates transcription (Initiation).

The polymerases binding sites are called promoters. It uses nucleoside triphosphate as substrate and polymerases in a template depended fashion following the rule of complementarity. After the initiation of transcription, the polymerase continues to elongate the RNA, adding one nucleotide after another to the growing RNA chain. Only a short stretch of RNA remains bound to the enzyme, when the polymerase reaches a terminator at the end of a gene, the nascent RNA falls off, so also the RNA polymerase.
The RNA polymerase is only capable of catalyzing the process of elongation. The RNA polymerase associates transiently with initiation factor sigma (\(\sigma \)) and termination factor rho (\(\rho \)) to initiate and terminate the transcription, respectively. Association of RNA with these factors instructs the RNA polymerase either to initiate or terminate the process of transcription.
In bacteria, since the mRNA does not require any processing to become active and also since transcription and translation take place simultaneously in the same compartment (since there is no separation of cytosol and nucleus in bacteria), many times the translation can begin much before the mRNA is fully transcribed. This is because the genetic material is not separated from other cell organelles by a nuclear membrane consequently; transcription and translation can be coupled in bacteria.

(i) Ovaries are the primary female sex organ producing eggs (ovum).
(ii) They are located one on each side of lower abdomen (pelvis).
(iii) The ovary is attached in pelvic wall uterus by an ovarian ligament called mesovarium.
(iv) It is an elliptical structure of 2-4 cm long
(v) Each ovary is covered by thin cuboidal germinal epithelium encloses ovarian stroma.
(vi) Below germinal epithelium is a dense connective tissue called tunica albuginea.
(vii) The stroma is differentiated into an outer cortex and an inner medulla.
(viii) The cortex is dense and granular due to follicular cells at varying development stages.
(ix) The medulla is a loose connective tissue with blood vessels, lymph vessels and nerve fibres.

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.

Morphological adaptations:
Root system is extensively developed. These roots may be of two types. They are Clinging roots and Aerial roots.
Clinging roots fix the epiphytes firmly on the surface of the supporting objects.
Aerial roots are green coloured roots which may hang downwardly and absorb moisture from the atmosphere with the help of a spongy tissue called velamen.
1. Stem of some epiphytes are succulent and develop pseudo bulb or tuber.
2. Generally the leaves are lesser in number and may be fleshy and leathery.
3. Myrmecophily is a common occurrence in the epiphytic vegetation to prevent the predators
4. The fruits and seeds are very small and usually dispersed by wind, insects and birds.

Jute
Botanical name : Corchorus spp.
Family: Malvaceae
Origin and Area of cultivation: Jute is derived from the two cultivated species (1) Core horns capsularis and (2) Colittorius is of African origin whereas C. Capsularis, is believed to Indo Burmaese origin. It is an important cultivated commercial crop in Gangetic plains of India and Bangladesh.
Uses: It is one of the largest exported fibre material of India. The jute industry occupies an important place in the national economy Of India. Jute is used for 'safe' packaging in view of being natural, renewable, bio-degradable and eco-friendly product. It is used in bagging and wrapping textile. About 75% of the jute produced is used for manufacturing sacks and bags. It is also used in manufacture of blankets, rags, curtains etc. It is also being used as a textile fibre in recent years.

Effects of deforestation:
(i) Burning of forest wood release stored carbon, a negative impact just opposite of carbon sequestration,
(ii) Trees and plants bind the soil particles. The removal of forest cover increases soil erosion and decreases soil fertility. Deforestation in dry areas leads to the formation of deserts.
(iii) The amount of runoff water increases soil erosion and also creates flash flooding, thus reducing moisture and humidity.
(iv) The alteration of local precipitation patterns leading to drought conditions in many regions. It triggers adverse climatic conditions and alters water cycle in the ecosystem.
(v) It decreases the bio-diversity significantly as their habitats are disturbed and disruption of natural cycles.
(vi) Loss of livelihood for forest dwellers and rural people.
(vii) Increased global warming and account for one-third of total CO₂ emission.
(viii) Loss of life support resources, fuel, medicinal herbs, and wild edible fruits.
Benefits of agroforestry:
(i) It is an answer to the problem of soil and water conservation and also to stabilize the soil (salinity and water table) reduce landslide and water run-off problem.
(ii) Nutrient cycling between species improves and organic matter is maintained.
(iii) Trees provide a micro climate for crops and maintain O₂ - CO₂ balanced, atmospheric temperature and relative humidity.
(iv) Suitable for dry land where rainfall is minimum and hence it is a good system for alternate land use pattern.
(v) Multipurpose tree varieties like Acacia are used for wood pulp, tanning, paper, and firewood industries.
(vi) Agroforestry is recommended for the following purposes. It can be used as Farm Forestry for the extension of forests, mixed forestry, shelterbelts, and linear strip plantation.

Types of succession
(a) Primary succession
The development of plant community in a barren area where no community existed before is called primary succession.
The plants which colonize first in a barren area is called pioneer species or primary community or primary colonies.
Generally, Primary succession takes a very, long time for the occurrence in any region.
Examples: Microbes, Lichen, Mosses.
The forest destroyed by fire and excessive lumbering may be re-occupied by herbs over period of times.
(b) Secondary succession
The development of a plant community in an area where an already developed community has been destroyed by some natural disturbance (Fire, flood, human activity) is known as secondary succession
Generally, this succession takes less time than the time taken for primary succession.
Example: The forest destroyed by fire and excessive lumbering may be re-occupied by herbs over Period of times.
(c) Autogenic succession
Autogenic succession occurs as a result of biotic factors
The vegetation reacts with its environment and modifies its own environment causing its own replacement by new communities. This is known as autogenic succession.
Example: In forest ecosystem, the larger trees produce broader leaves providing shade to the forest floor area. It affects the shrubs and herbs which require more light (heliophytes) but supports the shade tolerant species (sciophytes) to grow well.
(d) Allogenic succession
Allogeneic succession occurs as a result of abiotic factors.
The replacement of existing community is caused by other external factors (soil erosion, leaching, etc.,) and not by existing organisms.
Example: In a forest ecosystem soil erosion and leaching alter the nutrient value of the soil leading to the change of vegetation in that area.
(e) Autotrophic succession
If the autotrophic organisms like green plants are dominant during the early stages of succession it is called autotrophic succession, this occurs in the habitat which is rich in inorganic substances.
Since, green plants dominate in the beginning of this succession, there is a gradual increase in organic matter and subsequently the energy flow in the ecosystem.
(f) Heterotrophic succession
If heterotrophic organisms like bacteria, fungi, actinomycetes, and animals are dominant during the early stages of succession it is called heterotrophic succession.
Such a succession takes place in organic habitats.
Since heterotrophs dominate in the beginning of such succession, there will be a gradual decrease in the energy content.

Artificial Seed
1. Artificial seeds or synthetic seeds (synseeds) are produced by using embryoids (somatic embryos) obtained through in vitro culture.
2. They may even be derived from single cells from any part of the plant that later divide to form cell mass containing dense cyptoplasm, large nucleus, starch grains, proteins, and oils etc.
3. To prepare the artificial seeds different inert materials are used for coating the somatic embryoids like agrose and sodium alginate.