Class 12 Biology 2022 Board Exam

Though filariasis is not fatal, but the disease in humans is responsible for considerable suffering, gross deformities and disability. Write the scientific name of any two helminth worms causing the disease and state two chronic manifestations of filariasis.
[Max Marks: 2 | Sets: 57/2/1, 57/2/2, 57/2/3]

"Curd is easier to digest by humans than milk." Justify, giving two suitable reasons.
[Max Marks: 2 | Set: 57/2/1]

With the advent of sophisticated techniques of genetic engineering, we can now readily purify and isolate DNA. Name and explain the different steps involved in the separation and isolation of DNA fragments once cut by restriction endonucleases.
[Max Marks: 3 | Sets: 57/2/1, 57/2/2, 57/2/3]

An application of biotechnology in agriculture involves production of pest resistant plants using 'cry' genes from a bacterium. Name the bacterium. Explain why the 'cry' gene kills the pest but not the bacterium itself.
[Max Marks: 3 | Set: 57/2/1]

Explain the two physiological attributes which enable a kangaroo rat to survive in desert conditions.
[Max Marks: 2 | Set: 57/2/1]

(a) Study the given graphs (X) and (Y) depicting the annual variation in solar radiation on Earth from January to December and answer the undermentioned questions.
(i) Identify the graph that depicts (I) tropical region, and (II) temperate region, respectively.
(ii) Which of the two regions, (X) or (Y), will show high biological diversity and why ? Give two reasons.
[Max Marks: 2 | Sets: 57/2/1, 57/2/2, 57/2/3]

(a) A person suffering from AIDS dies of opportunistic infections (ARC) i.e., infections that could have been otherwise overcome.
(i) State one reason as to why an 'HIV' patient dies of 'opportunistic infections'.
(ii) Give the scientific name of one bacterium and one parasite which mainly attack a person suffering from AIDS.
(iii) Write the full form of the name of the widely used diagnostic test for AIDS.
[Max Marks: 2 | Sets: 57/2/1, 57/2/2, 57/2/3]

Lactic Acid Bacteria (LAB) sets milk into curd and also plays a very beneficial role for human health. Give any two suitable reasons.
[Max Marks: 2 | Set: 57/2/2]

"Large scale production of recombinant DNA requires the use of bioreactors."

OR
(b) RNA interference (RNAi) holds great potential as a therapeutic agent for the treatment of human diseases and as a bicontrol agent for controlling pests in the agricultural fields. An experiment was conducted to study the use of 'RNAi' for the potential treatment of disorders of cholesterol metabolism. Some people possess genetic mutations with elevated levels of 'ApoB' gene which predisposes them to coronary artery diseases.
Lowering the amount of 'ApoB' can reduce the number of lipoproteins and lower the blood cholesterol.
Tracy Zimmerman and her colleagues used RNAi in 2006 to reduce the level of 'ApoB' in non-human primates Cynomolgus monkeys.
(i) One group of monkeys were given RNAi treatment (Small interfering RNAs, SiRNAs) (doses 1 mg/kg SiRNAs), (ii) Second group of monkeys were given RNAi treatment (doses 2·5 mg/kg SiRNAs), and (iii) Third group of monkeys were injected saline as control .
The results of the experiments are illustrated in the graph given below :
(i) What do you interpret from the bars (X and Z) obtained after 264 hours of treatment of monkeys with saline and 2·5 mg/kg SiRNAs treatment ?
(ii) Name the category of organisms in the living world, where RNA interference (RNAi) takes place. Why ?
(iii) What is the basic principle involved in RNA interference (RNAi) in silencing the preferred genes ?
[Max Marks: 5 | Sets: 57/2/1, 57/2/2, 57/2/3]