Sexual Reproduction in Flowering Plants — BIOLOGY STD 12 Science — Question

What is Soil Profile? Explain.

Samya visited a zoo with her mother, on watching the cheetah, she wondered how he uses his forelimbs for running. While the same forelimbs in bats are used for flying. She wanted to know more about it and so asked her mother (a biology teacher) about it. Her mother explained her how forelimbs are modified in different animal groups for different functions.

1. What are such organs called?
2. Give an example of such organs from the plant world.
3. What led to the origin of such organs?
4. What are the values shown by Samya?

Describe the main ideas behind the biological control of pests and diseases.

Ranjana and Shilpi had a hot argument whether or not life is still originating on the earth today. Their neighbour, Mr. Kamal Mishra, a retired professor, who happened to be listening to the girls, called them and explained the matter in detail.

1. As a student of biology, what is your answer to the above problem? And why?
2. Recall the experiment of Miller, which simulated the primitive atmosphere.

1. What were the products obtained in his experiment?
2. How was energy provided in the experiment?

3. What would have been the energy source for origin of life on the earth?
4. Indicate the values shown by Mr. Kamal Mishra?

Give an account of the methods used in sequencing the human genome.

(a) Explain the process of DNA replication in prokaryotes.
(b) Name the phase in the cell cycle in which DNA replication takes place in the cell. What if after DNA replication there is no cell division in a cell?

In which categories have been classified the contraceptive methods. Describe any three methods in detail.

Why is aerobic degradation more important than anaerobic degradation for the treatment of large volumes of waste waters rich in organic matter. Discuss.

Give the term/ reason:
Mechanism responsible for parturition.