Board Paper of Class 12-Science 2013 Biology (SET 2) - Solutions

Describe the gene therapy procedure for an ADA-deficient patient. (2)

Expand the following and mention one application of each:

(i) PCR

(ii) ELISA

OR

(a) Mention the difference in the mode of action of exonuclease and endonuclease.

(b) How does restriction endonuclease function? 

Name any two sources of e-Wastes and write two different ways of their disposal.

Why the pyramid of energy is always upright? Explain.

Explain why very small animals are rarely found in polar region.

(a) How does cleistogamy ensure autogamy?

(b) State one advantage and one disadvantage of cleistogamy to the plant. (2)

When and where do chorionic villi appear in humans? State their function.

In a cross between two tall pea plants some of the offsprings produced were dwarf. Show with the help of Punett square how this is possible.

A young boy when brought a pet dog home started to complain of watery eyes and running nose. The symptoms disappeared when the boy was kept away from the pet.

(a) Name of type of antibody and the chemicals responsible for such a response in the boy.

(b) Mention the name of any one drug that could be given to the boy for immediate relief from such a response. (2)

(a) Explain how to find whether an E. coli bacterium has transformed or not when a recombinant DNA bearing ampicillin resistant gene is transferred into it.

(b) What does the ampicillin resistant gene act as in the above case? (2)

(a) Why are the fruit juices bought from market clearer as compared to those made at home?

(b) Name the bioactive molecules produced by Trichoderma polysporum and Monascus purpureus.

(a) Why a transgenic animals so called?

(b) Explain the role of transgenic animals in (i) Vaccine safety and (ii) Biological products with the help of an example each. (3)

How have human activities caused desertification? Explain.

OR

How does algal bloom destroy the quality of a fresh water body? Explain. 

(a) Explain how to overcome inbreeding depression in cattle.

(b) List three advantages of inbreeding in cattle.

(c) Name an improved breed of cattle.

Explain mutualism with the help of any two examples. How is it different from commensalism? (3)

Describe the structure of RNA polynucleotide chain having four different types of nucleotides.

(a) Why is human ABO blood group gene considered a good example of multiple alleles?

(b) Work out a cross up to F₁ generation only, between a mother with blood group A (Homozygous) and the father with blood group B (Homozygous). Explain the pattern of inheritance exhibited. (3)

With the help of any two suitable examples explain the effect of anthropogenic actions on organic evolution. 

(a) Draw a diagram of the structure of a human ovum surrounded by corona radiate. Label the following parts:

(i) Ovum

(ii) Plasma Membrane

(iii) State the function of Zona Pellucida. (3)

Describe the asexual and sexual phases of life cycle of Plasmodium that causes malaria in humans. (5)

OR

(a) What is plant breeding? List the two steps the classical plant breeding involves.

(b) How has the mutation breeding helped in improving crop varieties? Give one example where this technique has helped.

(c) How has the breeding programme helped in improving the public nutritional health? State two examples in support of your answer.

A child suffering from Thalassemia is born to a normal couple. But the mother is being blamed by the family for delivering a sick baby.

(a) What is Thalassemia?

(b) How would you counsel the family not to blame the mother for delivering a child suffering from this disease? Explain.

(c) List the values your counselling can propagate in the families.

(a) Draw a labeled schematic diagram of the transverse section of a mature anther of an angiosperm plant.

(b) Describe the characteristic feature of an insect pollinated flower.

OR

(a) Describe the events of spermatogenesis with the help of a schematic representation.

(b) Write two differences between spermatogenesis and oogenesis.