Ecosystems — BIOLOGY STD 12 Science — Question

The carbon atoms fixed by producers have to pass through three species. Mention the trophic level of the third species.

Name the plant source of cocaine. How does it affect the human body?

State a difference between a gene and an allele.

Write a brief note on the work of Walter Sutton and Theodore Boveri?

Why is a food web formed in nature?

What do you understand by tubectomy?

What is endometrium?

Which cell of male gametophyte produces the male gamete?

Name two STDs which can be transmitted through contaminated blood.

OR

Name two sexually transmitted diseases that do not specifically affect the reproductive organs.

Which type of cell division forms spermatids from the secondary spermatocytes?