Inheritance and Variation — BIOLOGY STD 12 Science — Question

Distinguish between Parasitism and Mutualism

Sakshi's father announced that the children are going to spend this weekend with their grandparents. During the journey, Sakshi saw some farmers who were spraying agrochemicals in their field. She requested her father to stop them. Her father praised her and contacted the farmers. He explained the side effects of such agrochemicals. He also suggested them to use biopesticides and biofertilisers instead of such chemicals. The farmers gave up spraying agrochemicals.

1. What did Sakshi's father explain to the farmers?
2. What are agrochemicals?
3. Why are biofertilisers or biopesticides preferred to chemical fertilisers or pesticides?
4. What values did Sakshi promote?

In one family, the four children each have a different blood group. Their mother has blood group A and their father has blood group B. Work out a cross to explain how it is possible.

Explain co–dominance taking an example of human blood groups in the population.

Differentiate between the genetic codes given below:

1. Unambiguous and Universal.
2. Degenerate and Initiator.

Explain the mechanism of sex determination in case of birds.

Sympathetic and parasympathetic nervous system.

How are the signals detected and amplified by electrocardiograph?

Performance enhancers.

1. Comment on the pattern in which all communities undergo a change in composition and structure with changing environmental conditions.
2. Explain 'Climax community' and 'Sere'.
3. Differentiate between primary and secondary succession with examples.