Pest Resistant Plants : Nematodes like Meloidgyne incognitia infects the roots of tobacco plants and causes reduction in yield. The infestation of these nematodes can be prevented by the process of RNA interference (RNAi). RNAi is present in all eukaryotic organisms as cellular defence by silencing of specific mRNA due to complementary dsRNA molecules that bind to and prevents translation of the mRNA.
The source of complementary dsRNA may be from an infection by viruses having RNA genomes or mobile genetic elements that replicate through RNA intermediate.
Nematode specific genes were introduced into host plant using Agrobacterium vectors. The parasite could not survive in a transgenic host expressing specific interfering RNA.

The process of breeding crops for higher level of vitamins and minerals, higher proteins, healthier fats, to improve public health is known as biofortification.
It helps to improve:
(i) Protein content and quality;
(ii) Oil content and quality;
(iii) Vitamin content: and
(iv) Micronu ient and mineral content. 
IARI has released several vegetable crops that are rich in vitamins and minerals. e.g. Vitamin A enriched carrots, spinach, pumpkin, vitamin C enriched bitter grourd, bathua, mustard, tomato, iron and calcium enriched spinach and bathua, protein enriched beans-lablab, broad, French and garden pea.

(i) The doctor must have injected the tetanus vaccine into the patient.
(ii) The vaccine/injection stimulates the body to make antibodies against the tetanus toxin.
(iii) The disease is tetanus caused by bacterium Clostridium tetani. The injection provides passive immunity.

Withdrawal syndrome.
These are the characteristic and unpleasant manifestations of the body,when regular dose of drugs/alcohol is abruptly discontinued.
Characteristics:
(i) Anxiety        
(ii) Excess sweating      
(iii) Shakiness  
(iv) Nausea.
In some cases withdrawal symptoms can be severe and even life-threatening.

a) Inbreeding depression can be overcome by outcrossing.
(b) (i) Inbreeding is necessary to evolve purelines in any animal, as it increases homozygosity.
(ii) Inbreeding exposes the harmful recessive alleles, which become eliminated by selection.
(iii) It helps in accumulation of superior genes and elimination of the less desirable ones.
(c)Hisardale, a breed of sheep.

Restriction endonucleases are enzymes that cut double-stranded DNA at very specific recognition sites. They were originally discovered in bacteria that use them to restrict the growth of viruses but are now among the workhorse enzymes of biotechnology and recombinant DNA research. The endonuclease that was first discovered was Hind II.

They are those plants, bacteria, fungi and animals in which a gene or genes have been introduced using recombinant DNAtechnology.They can be tailored to fulfil specific needs and perform functions which their natural counterparts can never perform. The factors are:
(i) The nature of gene transferred.
(ii) The nature of the host cell.

Eli Lilly prepared two DNA sequences corresponding to A and B chains of human insulin and introduced them in plasmids ofE. cold to produce insulin chains. Chains A and B were produced separately,
extracted and combined by creating disulfide bonds to form human insulin. Insulin in human pancreas is synthesised as a pro-hormone containing the C peptide, which is removed in mature hormone. The synthesised insulin did not contain C peptide and was prepared in m form.

Production of transgenic tobacco plant with resistance to nematode. Meloidegyne incognitia.
1. A nematode Meloidegyne incognitia infects the roots of tobacco plant and reduces its yield.
2. RNA interference (RNA i) is the process or the basis of which action plan have been developed to prevent this infestation.
3. The process involves {he splicing the specific mRNA by a complementary dSRNA molecule, that binds to and prevents the translation of mRNA.
4. This complementary RNA can be obtained from infection by viruses having RNA genomes or transposons that replicates via RNA intermediate.
5. Using Agrobacterium vector, the nematode specific genes were introduced into host plant.
6. Thus both sense and a.tisense strand of RNA are produced in the host cells.
7. These two RNA's are complementary to each other. formed as dSRNA that initiated RNA i spliced R.

Restriction endonuclease enzymes are called molecular scissors which can cut double stranded DNA at specific sites.
Role of restriction endonuclease.
1. Restriction endonuclease inspects the length of DNA sequence.
2. It find specific recognition sequence i.e. Palindromic nucleotide sequence in DNA.
3. These enzymes cut the strand of DNA a little away from centre of palindromic sites.
4. Thus restriction endonucleases leave overhanging stretches called sticky ends on each strand.

Restriction endonuclease enzymes are called molecular scissors which can cut double stranded DNA at specific sites.
Role of restriction endonuclease.
1. Restriction endonuclease inspects the length of DNA sequence.
2. It find specific recognition sequence i.e. Palindromic nucleotide sequence in DNA.
3. These enzymes cut the strand of DNA a little away from centre of palindromic sites.
4. Thus restriction endonucleases leave overhanging stretches called sticky ends on each strand.

MOET (Multiple Ovulation and Embryo Transplantation Technique). It is latest technique to produce super milch cows.
(i) Superovulation. It involves the stimulation of high milk-producing cows to ovulate more eggs by hormonal stimulation. Fertilization is done by artificial insemination. In this way, 4 to 10 embryos are developed in such cows.
(ii) Embryo transfer. In this, embryos are collected from superovulated cows. Each embryo is transplanted in the uterus of surrogate cows of inferior quality to produce large number of calves with good germplasm. It can also be done in sheep, goats and other livestock animals as well.

a) ADA - deficiency It is caused by the deletion of the gene for adenosine deaminase. The enzyme is crucial for the functioning of the immune system; hence the immune system gets affected.
(b) Vector - A retroviral vector Recipient - Lymphocytes.

Bt toxin gene has been cloned from the bacteria, and has been expressed in plants, to provide resistance to insects (without the need for synthetic insecticide), Bt toxin gene forms protein crystals, These crystals contain a toxic insecticidal protein. Bt toxin protein exists as inactive protoxin in the host, but once the insect ingests the inactive toxin, it is converted into active form of toxin, due to alkaline pH of the gut which solubilises the crystals, causing death of the insect

(a) Refer Quick Review (Same value points to be awarded in an explanation) 
(b) Purpose : Used to ligate with a vector for further cloning. Detection of bacteria or virus by amplification of their DNNdetection of HIV in AIDS patient. Detection of mutation in genes in suspected cancer patients.

(i) The desired gene is cut by using the enzymes restriction endonucleases. Firstly, the restriction endonucleases that recognise the palindromic nucleotide sequence of the desired gene is identified. The endonuclease inspects the entire DNA sequences to find and recognise the site. It cuts each of the double helix at a specific point, which is a little away from the centre of the palindromic site. The cutting site is between the same two bases on the opposite strands. This results in over-hanging of single stranded stretches, which act as sticky ends.
(ii) Multiple copies of the desired gene is synthesised by Polymerase Chain Reaction (PCR) method. In this method, the desired gene is synthesised in vitro. The double-stranded DNA is denatured using high temperature of 95°C and the strands are separated. Each separated strand acts as a template.
Two sets of oligonucleotide primers are annealed to the denatured DNA strands. The thermostable Taq polymerase extends the primers using nucleotides provided in the reaction mixture. Finally, the amplified fragments are ligated into recipient cells.