Microbes in Human Welfare — BIOLOGY STD 12 Science — Question

What is oestrous cycle? Differentiate between oestrous and menstrual cycle.

Haemophilia is a sex-linked recessive disorder of humans. The pedigree chart given below shows the inheritance of haemophilia in one family. Study the pattern of inheritance and answer the questions given.

1. Give all the possible genotypes of the members 4; 5 and 6 in the pedigree chart.
2. A blood test shows that the individual 14 is a carrier of haemophilia. The member numbered 15 has recently married the member numbered 14. What is the probability that their first child will be a haemophilia male?

The graph given below shows species-area relationship of a certain region.

a. Study the graph and explain what it represents.
b. After a while, a small area was taken for constructing a road which divided the region into two. Write the impact this construction would have on species richness of the region.

i. Construct a complete transcription unit with promotor and terminator on the basis of the hypothetical template strand given below.

ii. Write the RNA strand transcribed from the above transcription unit along with its polarity.

Write the specific symptoms of acquired immunity.

What do you think is the significance of reproductive health in a society?

Given below is the representation of amino acid composition of the relevant translated portion of B-chain of haemoglobin, related to the shape of human red blood cells.

1. Is this representation indicating a normal human or a sufferer from certain related genetic disease? Give reason in support of your answer.
2. What difference would be noticed in the phenotype of the normal and the sufferer related to this gene?
3. Who are likely to suffer more from the defect related to the gene representedthe males, the females or both males and females equally? And why?

While creation and presence of variation are directionless, natural selection is directional as it is in the context of adaptation. Comment.

Taking the example of white-winged moths and dark-winged moths of England in pre and postindustrialised era, explain evolution by natural selection.

OR

How can evolution by natural selection be explained by melanised moths before and after industrialisation in England?

OR

How did industrialisation play a role in Natural Selection of light and dark-coloured moth in England?

OR

What do these pictures (a) and (b) illustrate with reference to evolution? Explain.

Flowering plants have developed many devices to discourage self-pollination and to encourage cross pollination. Explain three such devices.