Subject

Biology

Class

CBSE Class 12

Pre Boards

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Sample Papers

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 Multiple Choice QuestionsLong Answer Type

31.

(a) Draw a diagrammatic sectional view of the female reproductive system of human and label the parts:

(i) where the secondary oocytes develop

(ii) which helps in collection of ovum after ovulation

(iii) where fertilization occurs

(iv) where implantation of embryo occurs.

(b) Explain the role of pituitary and the ovarian hormones in menstrual cycle in human females.
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32.

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

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33.

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

(b) How has the mutation breeding helps 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) Plant breeding: It is manipulation of plant species so as to produce plants with desired characters like better yield and disease resistance.

Classical plant breeding involves

(i) Hybridisation of pure lines.

(ii) Artificial selection for producing plant with desired characters of higher yield or resistance to diseases.

(b) Mutational breeding- creates genetic variations through changes in the base sequences within genes.

This results in new character which is not found in parents. Improved varieties can be produced by  inducing mutations artificially in the plants having desirable characters.

For example in mung bean resistance to yellow mosaic virus and powdery mildew was induced by limitations.

(c) Breeding crops with higher levels of vitamins and minerals or higher proteins and healthier fats has improved public health.

Breeding programmes have been designed with objectives of

(i) improved protein content and quality.

(ii) Oil content and quality

(iii) Vitamin content

(iv) Micronutrients and mineral contains maize hybrids having double amount of lysine and tryopophan have been developed. Similarly, IARI New Delhi has developed many vegetable crops rich in vitamins and minerals like spinach, carrots, pumpkin etc.
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34.

A child by the family 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 counseling can propagate in the families.
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