Evolution — BIOLOGY STD 12 Science — Question

Microbes have various contributions to the human welfare. For example, lactic acid bacteria help in checking disease causing microbes in our stomach. With reference to this fact, state the contribution of different microbes in the process of digestion in ruminants.

How do biofertilisers enrich the fertility of the soil?

Selecting the recombinants becomes cumbersome when antibiotic is inactive- explain.###How can we distinguish between recombinant and non recombinant plasmid? Illustrate.

Kanchan went to a garden and saw some flowers which were closed. She assumed that those flowers must be buds. But she was astonished to see that all the flowers of that plant were closed and none of them was open. She was confused and asked her queries to her teacher.

1. What do you think, are there any plants with closed flowers? Give an example.
2. Are such plants get pollinated? Explain.
3. What are such flowers/ plants called?
4. What values are shown by Kanchan?

What is acrosome?

How are alleles of particular gene differ from each other? Explain its significance.

What is mutation? Explain with the help of an example, how a point mutation does affect the genetic code. Name another type of mutation.

Human blood group is a good example of multiple allelism and co-dominance. Justify.

What are 'cloning sites' in a cloning vector? Explain their role. Name any two sites in pBR 322.

Express your opinion on removal of tribal people out of forest due to developmental activities in the forest.