Human Reproduction — BIOLOGY STD 12 Science — Question

Water pollinated (hydrophilous) plants.

State in what ways Stanley Miller stimulated the conditions of-

1. Primitive atmosphere on earth.
2. Energy source at the time of origin of life.
3. Formation of organic molecules of life to prove the theory of chemical evolution.

Given below are the events that are observed in an artificial hybridisation programme. Selection of parents → Emasculation → Bagging → Collection of pollen from other male plant → Dusting of pollen on stigma — Rebagging.
While, planning for crop improvement involving dioecious plants, which of the above mentioned steps would not be relevant?

What could be the possible explanation for greater vulnerability of amphibians to extinction as compared to other animal groups?

Answer the following questions:
What are mycorrhiza? How does it act as a biofertiliser?

Name the source of smack. Mention one way in which it affects the human body.

Name some traditional Indian foods made of wheat, rice and Bengal gram (or their products) which involve use of microbes.

Draw a diagram of the microscopic structure of human sperm. Label the following parts in it and write their functions.

1. Acrosome.
2. Nucleus.
3. Middle piece.

What are satellite DNA in a genome? Explain their role in DNA fingerprinting.