CBSE Class 12 Biology Previous Questions- Short Answer Type

1. Name an organism where cell division is itself a mode of reproduction? 
Ans: Unicellular

2. Why is tubecotomy considered a contraceptive method?
Ans: It is a surgical method of contraception

3. Write the percentage of F2 homozygous and heterozygous populations in a typical monohybrid cross?
Ans: Fifty percentage each

4. When does a species become founders to cause founder effect?
Ans: original drifted population becomes founders

5. Name two green house gases produced by anaerobic microbes.
Ans: Carbon dioxide and Methane

6. What is the host called that produces a foreign gene product? What is this product called?
Ans: Cloning vector, recombinant (protein)

7. Why do predators avoid eating Monarch Butterfly? How does the butterfly develop this protecting feature?
Monarch Butterfly
Ans: Monarch butterfly is distasteful. It develops a chemical during its caterpillar state by feeding on a poisonous weed.

8. Why is the use of unleaded petrol recommended for motor vehicles equipped with catalytic converters?
Ans: Lead in petrol inactivates catalysts thus causing emission of poisonous gases. 

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