Human Reproduction — BIOLOGY STD 12 Science — Question

Answer the following questions:
Where is morula formed in humans? Explain the process of its development from zygote.

Observe figure and answer the following questions.

1. What ecological term is used to describe the DDT accumulation at different trophic levels?
2. List any one effect of DDT accumulation on birds.
3. Will DDT accumulation lead to eutrophication?
4. Does it affect the BOD?
5. Name disease caused by accumulation of any heavy metal.

Vicky's mother was using the same mosquito repellent cream from last six years. She was regularly complaining that this cream has no effects on mosquitoes now. Hearing this, Vicky advised his mother to change the cream as regular usage has led the mosquitoes to develop resistance against it. His mother changed the cream and could notice its effect on mosquitoes.

1. Explain how mosquitoes were not affected by the previous cream?
2. On what factors, Darwin's theory was based?
3. Can you relate this incident to Darwin's concept? How?
4. Identify the values shown by Vicky.

What is meant by the term biopesticide? Name and explain the mode of action of a popular biopesticide.

A patient is suffering from ADA deficiency. Can the patient be cured? How?

Who gave theory of use and disuse of organs? Discuss in detail the inheritance acquired character?

Write a short note on uterus.

A woman with blood group “A” marries a man with blood group “O”. Discuss the possibilities of the inheritance of the blood groups in the following starting with “yes” or “no” for each:

1. They produce children with blood group “A” only.
2. They produce children some with “O” blood group and some with “A” blood group.

What are vegetative propagules? Name any four of them along with an example for each.