(a) What is GMO? List any five possible advantages of a GMO to a farmer.

(b) What is golden rice?

(c) Why does Bt toxin not kill the bacterium that produces it, but kills the insect that ingests it?

OR

(a) Differentiate the terms ‘Cry’ and ‘cry’.

(b) What are Cry proteins? Name an organism that produces it. How has man exploited this protein to his benefit?

(c) Name the source used to produce hepatitis-B vaccine using rDNA technology.

(a) GMO stands for genetically modified organism, which refers to an organism whose genetic material has been altered in a way that does not occur naturally through mating or natural recombination. This is typically achieved through the use of genetic engineering techniques.

Advantages of GMOs to a Farmer
(i) Crops becomes tolerant to abiotic stresses.
(ii) Less use of chemical pesticides.
(iii) Reduce post-harvest losses.
(iv) Efficiency of mineral usage increased in plants,
(v) Prevent exhaustion of fertility of soil.
(vi) Enhanced nutritional value of food.

(b) Golden rice is genetically modified rice in order to enhance the quantity of vitamin-A in it. Golden rice contains high levels of $\mathrm{\beta }$-carotene (golden colour) and other carotenoids

(c) Bt toxin is produced by Bacillus thuringiensis a soil bacterium. This toxin in the bacterium present in an inactive and crystalline form. It becomes active and toxic only when it is consumed by insects such as lepidopterans, etc., due to the alkaline pH of their gut. The activated toxin binds to the surface of midgut epithelial cells and create pores that cause cell swelling and lysis and eventually cause death of the insect.

OR

(a)'Cry' with a capital 'C' usually refers to the prefix used in the names of certain insecticidal proteins that are produced by the bacterium Bacillus thuringiensis (Bt). These proteins are toxic to certain pests, such as caterpillars, and are commonly used as a natural insecticide in agriculture. Examples of Cry proteins include Cry1Ab and Cry2Aa.

'cry' with a lowercase 'c' typically refers to the gene that codes for the Cry protein. The 'cry' gene is found in Bacillus thuringiensis and is responsible for producing the Cry protein.

In short, 'Cry' refers to a specific type of insecticidal protein, while 'cry' refers to the gene that codes for that protein.

(b) Cry proteins are insecticidal proteins produced by the bacterium Bacillus thuringiensis (Bt). These proteins are toxic to certain pests, such as caterpillars, and are commonly used as a natural insecticide in agriculture.

Bacillus thuringiensis is a soil bacterium that produces different types of Cry proteins, each of which is specific to certain insect pests. For example, Cry1A proteins are toxic to lepidopteran pests, while Cry3 proteins are toxic to coleopteran pests.

Humans have exploited the insecticidal properties of Cry proteins by developing Bt crops, which are genetically modified to produce these proteins. Bt crops are resistant to insect pests and require less pesticide use, which can reduce environmental pollution and decrease production costs for farmers.

Bt cotton is one example of a Bt crop that has been widely adopted in agriculture. Bt cotton produces a Cry protein that is toxic to the bollworm, a common cotton pest. By producing this protein, Bt cotton can resist bollworm infestations without the need for insecticide applications, which can reduce pesticide exposure for farmers and reduce the risk of developing resistance to insecticides in the pest population.

Overall, Cry proteins are a useful tool in agriculture for controlling insect pests while reducing environmental impact and improving crop yields.

(c) Recombinant DNA technology used in
i. The production of antigenic polypeptides of pathogen in bacteria or yeast.
ii. Production of vaccines. Source of hepatitis-B vaccine is yeast.