Science (English Medium) कक्षा १२ - CBSE Important Questions

Cite an example where more than one adaptive radiations have occurred in an isolated geographical area. Name the type of evolution your example depicts and state why it is so named.

What role does an individual organism play as per Darwin's theory of natural selection?

Mention any four special adaptive evolved in parasites for their parasite mode of life.

Explain divergent evolution with two examples. 

Answer the following question.
Write two differences between Homo erectus and Homo habilis.

Write two differences between Homo erectus and Homo habilis

Answer the following question.
Write the characteristics of Ramapithecus, Dryopithecus, and Neanderthal man.

According to the Hardy-Weinberg principle, the allele frequency of a population remains constant. How do you interpret the change of frequency of alleles in a population?

How does the Hardy-Wienberg equation explain genetic equilibrium?

How is Hardy-Weinberg's expression “(p² + 2pq + q²) = 1” derived?

List any two factors that can disturb the genetic equilibrium.

At a particular locus, the frequency of allele A is 0.8, and that of allele a is 0.2. What would be the frequency of heterozygotes in a random mating population at equilibrium?

The graphs below show three types of natural selection. The shaded areas marked with arrows show the individuals in the population who are not selected. The dotted vertical lines show the statistical means.

character Graph A	character Graph B	character Graph C

1. What names are given to the types of selection shown in graphs A, B and C?
2. After the selection has operated for several generations in the above populations indicated as, Graph A, B and C, graphically illustrate the probable results.

Explain the various types of cancer

It is generally observed that the children who had suffered from chickenpox in their childhood may not contract the same disease in their adulthood. Explain, giving reasons, the basics of such immunity in an individual. Name this kind of immunity.

State the cause of adenosine deaminase enzyme deficiency.

How does smoking tobacco in human lead to oxygen deficiency in their body?

Highlight the role of thymus as a lymphoid organ.

A group of youth were having a ‘rave party’ in an isolated area and was raided by police. Packets of ‘smack’ and syringes with needles were found littered around.

1. Why is taking ‘smack’ considered an abuse?
2. Write the chemical name of ‘smack’ and the name of its source plant.
3. Syringes and needles used by the youth for taking the drug could prove to be very fatal. Why?

What are interferons?