CBSE Class 12 Biology Sample Paper 2013 Set E

SECTION - A

Q.1. How can pollen grains of wheat and rice which tend to lose viability within 30 minutes of their release be made available months later for breeding programmes?

Q.2. Why are lichens regarded as pollution indicators?

Q.3. Name two STDs which can be transmitted through contaminated blood.

Q.4. Why are owners of motor vehicles equipped with catalytic convertors advised to use unleaded petrol? 

Q.5. What is secondary productivity?

Q.6. How are two short polypeptide chains of insulin linked together?

Q.7. A haemophilic son was born to normal parents. Give the genotypes of the parents.

Q.8. How is the presence of cyanobacteria in the paddy fields beneficial to rice crop?

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SECTION - B

Q.9. Why is it necessary to emasculate a bisexual flower in a plant breeding programme? Mention the condition under which emasculation is not necessary.

Q.10.How is ‘mutation’ explained by Hugo de Vries as different from the Darwinian variations?

Q.11.Explain the response initiated when a dose of vaccine is introduced into the human body.

Q.12.Name the natural source of agarose. Mention one role of agarose in biotechnology.

OR

List the three molecular diagnostic techniques that help to detect pathogens from suspected patients. Mention one advantage of these techniques over conventional methods.

Q.13.How does the human body maintain constant temperature both in summers and winters

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