Each testicular lobule contains 1-3 highly coiled seminiferous tubules. Each tubule is lined on its inside by two types of cells. The cuboidal cells are called male germ (spermatogenic) cells and few large pyramidal (supporting cells) are called Sertoli or nurse cells.
The former gives rise to sperms while the latter provide nutrition to the germ cells. 

Male gamete is minute and motile to move to the female gamete. Female gamete is large and contains food for development of embryo.

Foetal ejection reflex is neuroendocrine mechanism initiated by fully formed foetus and placenta which helps in parturition. It operates as below:
1.Foetus secretes hormone from its adrenal glands. These hormone stimulate the posterior pituitary of the mother to release oxytocin.
2.Oxytocin causes forceful contraction of smooth muscles of myometrium called labour pains, which further stimulates more secretion of oxytocin.
3.The stimulatory reflex between uterine contraction and oxytocin secretion continues which causes more forceful contraction of uterine muscles.
4.Uterine contractions pushes the young gradually out through the dilated cervix(caused by relaxin) and vagina.

1. Histone proteins help in packaging the giant molecules of DNA into nuleosomes to be accomodated into the nucleus
2. Non-histone chromosomal proteins help in packaging of chromotin at higher levels.

(i) Spermiogenesis is the process of transformation of spermatids into flagellated spermatozoa.
(ii) Spermiation is the process of release of spermatozoa from the seminiferous tubules.

(a) Streptococcus pneumoniae:
S - Strain (virulent) injected into mice ---> mice die
R - strain injected into mice ---> mice alive
S - strain (heat killed) injected into mice ---> mice alive
R - strain (alive) + S (heat killed) strain inject into mice ---> mice die
As the R strain (non-virulent) picked up genetic material from S strain (virulent) and get transformed.
(b) They (worked on the bio-chemical nature of transforming principle in Griffith's experiment) purified proteins DNA and RNA from heat killed S cells, they discovered protein digesting enzyme (protease) RNA digesting enzyme (RNese) did
not affect transformation, Digestion with DNase inhibited transformation, concluded DNA is the heredity material.

Ontogeny is embryonic development, i.e. the origin and development of an organism from an embryo to an adult.
Phylogeny is ancestral history, i.e. the evolutionary development and history of a species or higher taxonomic grouping of organisms.                                     

(i) ABO blood group system is inherited.A and B are dominant over O, but A and B express in the presence of each other.
(ii) Genotypes of parents;\({ I }^{ A }{ I }^{ O }\times { I }^{ B }{ I }^{ O }\) 
(iii) Carl Landsteiner
(iv) It shows following three phenomenon
(a) Dominance-recessive  
(b) Co-dominance  
(c) Multiple alleles

Phenotypes                               Smooth seeded X and red flowered                              Smooth seeded and
Parents                                          SsRr                                                                                          White flowered SsRr
Genotype

1.Both the strands of parent DNA function as template strands.
2. On the template strand with \({ 3 }^{ ' }\longrightarrow { 5 }^{ ' }\) polarity, the new strand is synthesised as a continuous stretch as the DNA polymerase can carry out polymerisation of the nucleotides only in \({ 5 }^{ ' }\longrightarrow { 3 }^{ ' }\)direction; this is called continuous synthesis and the strand is called leading strand.
3. On the other template strand with \({ 5 }^{ ' }\longrightarrow { 3 }^{ ' }\) polarity, the new strand is synthesised from the point of replication fork, also in \({ 5 }^{ ' }\longrightarrow { 3 }^{ ' }\) direction, but in short stretches; they are later joined by DNA - ligases to form a strand, called lagging strand.

In wind pollinated flowers,
(i) The stamens are well-exposed, so that pollen grains are easily dispersed in wind currents.
(ii) The stigma is large and often feathery, to easily trap the air-borne pollen grains.
(iii) The pollen grains are light and non-sticky, to be transported in wind currents.
(iv) Pollen grains are produced in enormous quantity.
(v) Numerous small flowers are packed into an inflorescence.
(vi) There is a single ovule in the ovary of these flowers.

Definition
Divergent evolution is a type of evolution where similar body structures have evolved to perform different functions based on the need of the organism.
Cause/driving force
Due to the presence of different environments, certain body parts of organisms have modified their functions so that they can adapt to these habitats. These body parts are called homologous organs as they have similar body structure but different functions.
Significance
Divergent evolution indicates that the organisms have a common ancestor but they develop different characteristics (due to the changing environment) giving rise to new species.
Examples
In animals :
The forelimbs of Whales, Bats, Cheetahs and Humans have a similar bone structure (contain humerus, radius, ulna, carpels, phalanges) but they perform different functions. In whales it is used for swimming, Bats use it for flying, Cheetahs for running and Humans for different functions.
The hearts in various vertebrates (fishes, amphibians, reptiles, birds, and mammals) have similar structure but vary in the number of chambers they have due to diverse habitats and energy requirements.
In plants :
The thorns of Bougainvillea and the tendrils of Cucurbita are modified branches i.e. they have the same basic structure and common ancestor but the functions are different. The thorns are used for protection and the tendrils are used as support to the plant.

(i) The three types of RNA are:
(a) Messenger RNA (mRNA)
(b) Transfer RNA (tRNA)
(c) Ribosomal RNA (rRNA)
(ii) Functions of RNAs
(a) Messenger RNA (mRNA)
1. It brings the genetic information of DNA transcribed on it, to ribosomes for protein synthesis.
2. It decides the sequence of amino acids in a polypeptide chain.
(b) Transfer RNA (tRNA)
1.It acts as an adapter molecule, that reads the code on mRNA on one hand and binds to a specific amino acid on the other hand.
2. By its anticodon, it recognises the codon and leaves the amino acid coded by the mRNA at the site of protein synthesis.
(c) Ribosomal RNA (rRNA)
1. It forms the structure of ribosomes.
2.It also plays a catalytic role; 23S rRNA in bacteria is the enzyme, ribozyme that catalyses the formation of peptide bond.

(a) A-Template strand = 1
B-Coding strand =1
Template strand has polarity 3'-5'
Coding strand has polarity 5'-3'
On the basis of polarity with respect to promoter
(b) In initiation sigma factor associates with RNA polymerase to initiate transcription, Rho factor gets associated to RNA polymerase to terminate transcription.
(e) RNA polymerase I -Transcribes -RNAs
RNA polymerase III-Transcribes tRNA / 5srRNA/5nRNA
(OR)
Prokaryotes : Negatively charged DNA, is held with positively charged proteins, in nucleoid, DNA in nucleoid is organised in large loops held by protein.
Eukaryotes : In nucleus the negatively charged DNA, is wrapped around positively charged histone octomer, to formnucleosome, nucleosomes are repeated, to constitute chromatin, at higher level additional set of non-histone chromosomal protein gets associated with chromatin.

New research suggests that despite modern technology and industrialisation, 'humans continue to evolve'. In the last 10,000 years or so, the pace of our evolution has speeded up 100 times creating more mutations in our genes and hence, greater natural selection.
Some clues that show humans are evolving are
(i) Lactose Tolerance: Historically the gene that regulated human's ability to digets lactose was shut down as infants are weaned off of their mother's breast milk. However, adult human in regions of Africa and Northern Europe developed the ability to tolerate lactose in their diets as recent as 5,000 or 6,000 years ago due to mutations.
(ii) Wisdom Teeth: Our ancestors had much bigger jaws than we do to lactose their eating habits. Today our jaws are much smaller and wisdom teeth are often impact estimates say that they will disappear in the coming population.

(b) Tapetum is the innermost wall layer; whose cells possess dense cytoplasm and more than one nucleus.
 It nourishes the developing pollen grains.
(c) (i) The exine of pollen grains is made of sporopollenin, which can withstand high temperature and action of strong acids or alkalies; no enzyme can degrade sporopollenin and hence, pollen grains are well preserved as fossils.
(ii) Pollen grains are rich in nutrients and hence, are used in the form of tablets as food supplements.

(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation
The primitive earth conditions were so that they led to the production of organic molecules like proteins, RNA, etc.

(d) If both Assertion and Reason are false.
Explanation:
When bacteria Streptococcus pneumoniae are grown on a culture plate, some produce smooth shiny colonies (S) while others produce rough colonies (R). This is because the S strain bacteria have a mucous (polysaccharide) coat, while R strain does not. Mice infected with the S strain (virulent) die from pneumonia infection but mice infected with the R strain do not develop pneumonia. In Griffith’s experiment, some ‘transforming principle’, transferred from the heat-killed S strain, had enabled the R strain to synthesize a smooth polysaccharide coat and become virulent which must be due to the transfer of the genetic material. This is known as transformation.

(c) : In mammals, the presence of a Y chromosome is required for the development of a male sex phenotype. In contrast, the Y chromosome plays no Significant role in sex determination in Drosophila. A Y chromosome is required for maleness, moreover, the presence of a single Y chromosome is sufficient even in the presence of several X chromosomes ie.g., XXXXY).

(b): Of the various insects, bees are the main flower visitors. Bees handle up to 80% of all pollination done by insects. All the bee pollinated flowers are brightly coloured, possess sweet fragrance, and / or produce nectar. Bees are colour blind for red and are fond of yellow, violet and purple. The bees visit flowers to collect their food (pollen and nectar) and in the process prove instrumental in bringing about pollination.

(i) (a) : When a haemophilic man (X^hy) marries a woman whose father was haemophilic and mother was normal i.e., carrier woman (XX^h), then 50% daughters are carriers and 50% are haemophilic. This can be explained as follows:

(ii) (d) : When a man whose father was colourblind and mother was normal (i.e., normal man XY) marries a woman whose father was haemophilic and mother was normal (i.e., carrier haemophilic woman X^hX), then 25% male progenies and 25% female progenies carry the gene of haemophilia.

(iii) (a) : Haemophilia is sex linked recessive Mendelian disorder.
(iv) (d) : When Anup who is colourblind (X^cy) marries Soni who is normal (XX) then 0%, chances that their son will have colourblindness.

(v) (a)