(a) Explain how golden rice can prevent child blindness? 

(b) Explain how transgenic animals serve as model for human disease? 

(c) “The mature insulin molecule consists of three short polypeptide chain.”  Explain

OR

(a) How do the improvement of crop plants through genetic engineering more advantageous than conventional breeding? 

(b) What are four main objectives of genetically modified crop plants?

(c) How does RNA interference help in developing resistance in tobacco plant against nematode infection?
 

(a) Golden rice is biofortified crop which contain beta-carotene and beta-carotene convert into Vitamin A. Vitamin A contains retinol which is good for the eye sight.  

(b) Disease models of transgenic animals are used to study tumor development, immune regulation, etc. This provides insights into the genetic origin. Transgenic models exist for many human diseases such as cancer, cystic fibrosis, rheumatoid arthritis and Alzheimer’s at present.

(c) Mature insulin does not contain three polypeptide chain. Proinsulin contains 3 polypeptide chain A, B and C. It loses C peptide during processing into mature insulin. So, mature insulin has two polypeptide chains A and B linked by disulphide bridges.

OR

(a) Genetic engineering allows only the modification of desired character in plant, whereas conventional breeding allows the modification of both wanted and unwanted characters .

(b) Four main objectives of genetic modified crops are
i. To increase crop productivity.
ii. Make resistance against pests and diseases.
iii. To increase food quality.
iv. To increase medical benefits.

(c) Pathogen Meloidogyne incognita is a nematode that infects the roots of tobacco plants and reduces productivity. RNA interference (RNAi) prevents infection by silencing specific mRNA and producing ds RNA. Translation comes to halt because of ds RNA. As a result no further infection take place.