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CBSE Class 12 Biology Solved Question Paper 2018

Short Answer Type

21.

Give an example of a bacterium, a fungus and an insect that are used as biocontrol agents.

22.

How has the development of bioreactor helped in biotechnology?

23.

Name the most commonly used bioreactor and describe its working.

24.

Explain the roles of the following with the help of an example each in recombinant DNA technology:

(a) Restriction Enzymes

(b) Plasmids

25.

Differentiate between Parthenocarpy and Parthenogenesis. Give one example of each.

26.

Medically it is advised to all young mothers that breastfeedings is the best for their newborn babies. Do you agree? Give reasons in support of your answer.

27.

Draw a diagram of a mature human sperm. Label any three parts and write their functions.

28.
Expand VNTR and describe its role in DNA fingerprinting.

VNTR stands for “Variable Number of Tandem Repeats”.
The VNTR belongs to a class of satellite DNA referred to as mini-satellite. A small DNA sequence is arranged tandemly in many copy numbers. The copy number varies from chromosome to chromosome in an individual. The numbers of repeat show very high degree of polymorphism. As a result th size of VNTR varies in size from 0.1 to 20 kb. Consequently, after hybridization with VNTR probe, the autoradiogram gives many bands of differing sizes. These bands give characteristic pattern for an individual DNA which is used to identify individuals.

29.

List any two applications of DNA fingerprinting technique.

30.

Looking at the deteriorating air quality because of air pollution in many cities of the country, the citizens are very much worried and concerned about their health. The doctors have declared a health emergency in the cities where the air quality is very severely poor.

(a) Mention any two major causes of air pollution.

(b) Write the two harmful effects of air pollution on plants and humans.

(c) As a captain of your school Eco-club, suggest any two programmes you would plan to organise in the school so as to bring awareness among the students on how to check air pollution in and around the school