(a) Positive terminal-B' Negative terminal-' A'
(b) DNA being negatively charged, moves towards the positive electrode (anode)
(c) By elution-separated bands of DNA are cut out from the agarose gel and extracted from the gel piece.

(i) The diagram is proinsulin as it contains C-peptide.
(ii) Mature insulin is synthesised by removal of extra stretch called C-peptide.

Source-Bacillus thuringiensis. Target pest-cotton bollworms.

DNA ligase.

1. Biochemical oxygen demand (BOD) represents the amount of dissolved oxygen that would be consumed if all the organic matter in one litre of water were oxidised by microorganisms.
2. More value of BOD means the water sample is polluted by organic matter

(i) Stem cells are the young, immature totipotent cells which differentiate into any type of cells, tissue or organs under specific conditions.
(ii) Placental stem cells or the umbilical stem cells to cure patients with immune system failure.
(iii) T - lymphocytes and B - lymphocytes.
(iv) Leukaemia, myeloma, lymphoma and Hodgkin's disease can be curved, to save thousands of victims of cancer which die every year.
(v) Bone marrow transplant rebuild the body's immune system. To avoid rejection of new cells by body, a perfect good match has to found before a transplant can go a head.

Microbes can absorb and accumulate the chemicals as well as metabolise the same so as to clean environment. The phenomenon is called bioremediation. Pseudomonas putida has been genetically modified (chakravarthy bug) to metabolise most of the pollutant chemicals including oil spills.

No, eukaryotic cells do not have restriction endonucleases.
All the restriction endonucleases have been isolated from various strains of bacteria. Prokaryotes/bacteria have this enzyme as a defence mechanism to destroy the foreign DNA or to restrict the growth of bacteriophages.

The milk will be converted into fermented milk and finally into curd. The process is called lactic acid fermentation. During this process, the microorganisms such as Lactobacillus, Pediococcus, Streptococcus and other commonly called lactic acid bacteria (LAB)  convert Lactose (Carbohydrates) into lactic acid by fermentation and coagulate milk protein (Casein) to produce a homogenous curd.
Carbohydrate \(\underrightarrow { LAB } \)  Lactic acid + CO₂
The products of fermented milk are Dahi, Lassi, Buttermilk, Shrikhand, etc. These products have originated from India.

The best example of a natural form of genetic engineering is Agrobacterium tumefaciens inserting genes into plants and getting the plants to express those genes in the form of proteins. This infection results in the formation of a gall or tumour in the host.

a = 5'- G-G-A-T-C-C-3',    
b = Escherichia coli RY 13,    
c = Hin d II
3'-C-C-T-A-G-G-5'

Monascus purpureus is a yeast which produces statins (a) that is used as a blood-cholesterol lowering agent (b) Penicillium notatum (c) is a mould (fungus) which produces penicillin (d) that is used as an antibiotic.
Trichoderma polysporum (e) is a fungus which produces cyclosporin-A that is used as an immunosuppressive agent (f) in organ-transplant patients.

Five examples of palindromic DNA sequences are
(i) 5'-A  A G C T T-3' 3'-T T C G A A-5'
(ii) 5'-G G A T C C-3' 3'-C C T A G G-5'
(iii) 5'-A G G C C T-3' 3'-T C C G G A-5'
(iv) 5'-G A A T T C-3' 3'-C T T A A G-5'
(v) 5'-A C T A G T-3' 3'-T G A T C A-5'

(a) Isolation of nematode-specific gene.
(c) Production of sense and anti-sense RNA in the host.
(d) Formation of ds RNA (as the sense and anti-sense RNA are complementary to each other). if Silencing of specific mRNA of the nematode.
(g) Host expresses the interfering RNA.
(h) Parasite cannot survive and host (tobacco) plant is protected.

1. Organic farming is a holistic approach that seeks to develop an understanding of the webs of interaction among the myriads of organisms that form the flora and fauna of the field.
2. The organic farmer works to create a system where the insects (called pests) are not eradicated, but kept at manageable levels by a complex system of checks and balance within a living and vibrant ecosystem.
3. According to the organic farmer, the eradication of the creatures, called pests, is not only possible but also undesirable, because many beneficial predatory and parasitic insects cannot survive without them.
4. Such a use of biocontrol measures reduces the use of chemical pesticides and thereby the pollution.

(i) Because Bt cotton is resistant to some insects and therefore it decreases the need of pesticides.
(ii) The advantages of genetically modified crops are:
(a) These are tolerant to abiotic stresses.
(b) These have enhanced nutritional value of food.
(c) These are resistant against some plant pathogens.
(d) These have reduced the use of chemical pesticides.

(i) The DNA containing insulin gene is isolated from human cell. Two DNA sequences corresponding to A and B chains of human insulin are prepared and introduced into the plasmid vector of E. coli to produce insulin chains A and B. Separate chains are extracted and combined by creating disulphide bonds to form genetically engineered human insulin which is also called as humilin.
(ii) The insulin produced through recombinant DNA technology is better than one used earlier by diabetic patients because it does not produce sensitive allergic reactions and other immunological complications, whereas the earlier insulin extracted from the pancreas of slaughtered cattle and pig cause allergy or other types of reactions, because they are foreign proteins.
(iii) Sohan exhibited the sense of responsibility and care towards his parents. He is aware of various biotechnical applications. He makes use of this knowledge to convince his mother

(a) DNA sequences of the vector as well as the source are cut by the same restriction enzyme like EcoRI, in a palindromic sequence. (The cut ends overhang to as sticky ends in the medium.)
(b) These cut ends fragments are to be extracted from the culture medium using gel electrophoresis. This has an agarose gel matrix. Fragments are fed in the wells. They are negatively charged. So, they move towards anode under an electric field through the gel. Smaller fragments move faster, thus separated.
(c) Fragments are now added to the medium containing the vector DNA. The sticky ends facilitates the action of the enzyme ligase and join the source DNA to the vector.

(i) People are careless, superstitious and unaware.
(ii) We can help in decreasing pollution of rivers by adopting following habits:
(a) By throwing litter or polybags in dustbin instead of rivers.
(b) By using environment friendly household products such as washing powder, household cleaning agents, etc.
(c) By planting more and more trees, which prevent fertilisers, pesticides and contaminated water from running in to nearby rivers.
(iii) Some advantages of saving rivers are:
(a) Constant supply of water and food to us.
(b) Huge supply of all natural fertilisers, which is good for growing crops.
(iv) Government has initiated Ganga Action Plan and Yamuna Action Plan to save these rivers from pollution.