(i)The codon AUG is the initiation codon and codes for methionine, the initiator amino acid.
(ii) UAG IS a stop codon that does not code for any amino acid and brings about the termination of the translation process.

Polarity of the two strands of the fork to be shown and polarity as well as arrow mark of the lagging and leading strands to be shown with correct labellings.

Oral pills contain progrestins and estrogen which check ovulation; Combined pill, Mala D and Saheli.

1. IVF (In Vitro Fertilization)  involves fusion of sperm and ovum in a culture medium outside the female genital tract.It should be performed under following conditions:
(a) Removal of unfertilized ovum from ovary of female or female reproduction tract with a laparoscope.
(b) Ovum is kept in culture medium in an aseptic conditions.
(c) Collection of semen of male in hygienic manner.
(d) Gamates are induced to fuse under simulated conditions to form zygote.
2. ET  (Embryo Transfer)  involves transfer of developing embryo from culture medium into female reproductive tract.It occurs in the presence of following conditions:
(a) Zygote is induced to develop in culture medium.It can implanted upto 32 cells stage into fallopian tube or uterus.
(b) Endometrium is stimulated to proliferate for implantation.

1.The presence of 2'OH-group of ribose makes RNA more labile and prone to degradation.
2.In the heat-killed S-strain,it would not have remained functional and hence would not have transformed the R-cells into S-cells.

Vasectomy in males & Tubectomy in females Devoid of ill effects of contraceptive (like nausea, abdominal pain, breakthrough bleeding, irregular menstruation or breast cancer), Reversibility is very poor.

(i) i-Regulatory gene, p - Promotor gene.
(ii) Inducer is lactose.
Functions
(a) Enters the cell and binds to the repressor and inactivates it.
(b) As a result, repressor cannot bind to the operator .This allows  RNA polymerase to have access to the promotor and transactions proceeds.

Charging of tRNA
1. The amino acids are activated in the presence of ATP and linked to their cognate tRNA; this process is called charging of tRNA or amino acylation of tRNA.
2. This process is necessary as the formation of peptide bond between the amino acids is favoured energetically, when they are brought together
3. The activation of amino acids by ATP provides the energy for the formation of peptide bond.

(a) Since tRNA on one hand binds to a specific amino acid and on the other hand reads the codon of the amino acid bound to it through its anticodon, it is called an 'adapter'.
(b)

It actually looks like an inverted L.

(a) High degree of polymorphism forms the basis of DNA fingerprinting. It involves isolation of DNA, digestion of DNA by restriction endonucleases, separation of DNA fragments by electrophoresis, transferringlblotting of separated DNA fragments to synthetic membranes (nylon or nitrocellulose), Hybridisation using labelled VNTR probes, detection of hybridised DNA fragments by authoradiography.
DNA from blood/hair follicle/skin/bone/saliva/ sperm
(b) Helps as identification toolinforensic applications, in determining population and genetic diversity and helps in paternity testing.

(a) The bead-like structures are the nucleosomes.
1. There is a set of positively charged proteins, called histones, rich in basic amino acid residues, lysine and arginine.
2. Histones are organised to form a unit of eight molecules, called histone octamer.
3. The negatively charged DNA is wrapped around the positively charged histone octamer, to form a nucleosome; a nucleosome contains 200 bp of DNA helix.
(b) The nucleosomes form the repeating units of the chromatin fibre in the nucleus; these nucleosomes of a chromatin are seen as the beads-on-string structure under electron microscope.
1. The chromatin fibres are further coiled and condensed at metaphase stage to form the chromosomes.
2. The packaging of chromatin at higher levels requires another set of proteins, called non-histone chromosomal (NHC) proteins.

1. It was to show that DNA replication is semi conservative.
2. After completion of replication, each new/daughter molecule of DNA has one parental strand and one newly synthesised strand; this is called semiconservative replication of DNA.
3. Experiment
Mathew Meselson and Franklin Stahl performed the experiment.
4. They grew E.coli. in a medium containing \(^{ 15 }{ { NH }_{ 4 } }Cl,\) until \(^{ 15 }N\) was incorporated in the two strands of newly formed E.coli cells; this 'heavy' DNA can be separated from the normal \(^{ 14 }N-DNA\) by centrifugation in cesium chloride (CsCI) density gradient.
5. Then they transferred the cells into a medium with normal \(^{ 14 }{ { NH }_{ 4 } }Cl\) and took out samples at various time intervals.
6. They extracted the DNA and centrifuged it to measure the densities.
7. The DNA extracted from cells after one generation after transfer from the \(^{ 15 }{ { N } }\) medium to \(^{ 14 }{ { N } }\) medium (i.e. after about 20 minutes), had an intermediate/hybrid density.
8. The DNA extracted after two generations (i.e. after 40 minutes) consisted of equal amounts of 'light' DNA and 'hybrid' DNA.
This proves that after replication, each DNA molecule has one parental strand and one newly synthesised strand, i.e. replication is semiconservative.

(b): Transformation is the change in the genetic constitution of an organism by picking up genes present in the environment. Pneumococcus has two strains - virulent (S) and non-virulent (R). The virulent strain causes pneumonia. R-type bacteria form irregular or rough colonies and did not produce any disease while the S-type bacteria cause pneumonia and then death in the mice. Griffith injected a combination of live R-type and heat killed S-type bacteria into mice. While some mice survived, others developed the disease of pneumonia and died. Autopsy of the dead mice showed that they possessed both the types of bacteria in living state though the mice had been injected with dead virulent and living non-virulent bacteria. The occurrence ofliving S-type virulent bacteria is possible only by their formation from R-type non-virulent bacteria which pick up the trait of virulence from dead bacteria. The phenomenon is called transformation.

(i) (a)
(ii) (a)
(iii) (a)
(iv) (c)