Science (English Medium) कक्षा १२ - CBSE Question Bank Solutions

As a senior biology student you have been asked to demonstrate to the students of secondary level in your school, the procedure(s) that shall ensure cross-pollination in a hermaphrodite flower. List the different steps that you would suggest and provide reasons for each one of them.

Why do moss plants produce very large number of male gametes? Provide one reason. What are these gametes called?

Geitonogamous flowering plants are genetically autogamous but functionally cross-pollinated. Justify.

Describe the characteristic features of wind pollinated flowers.

Explain the post-pollination events leading to seed production in angiosperms.

List the different types of pollination depending upon the source of pollen gain.

A flower of tomato plant following the process of sexual reproduction produces 240 viable seeds.

Answer the following questions giving reasons :

(a) What is the minimum number of pollen grains that must have been involved in the pollination of its pistil?

(b) What would have been the minimum number of ovules present in the ovary?

(c) How many megaspore mother cells were involved?

(d) What is the minimum number of microspore mother cells involved in the above case?

(e) How many male gametes were involved in this case?

A flower of tomato plant following the process of sexual reproduction produces 200 viable seeds.

Answer the following questions giving reasons :

(a) What would have been the minimum number of ovules present in pre-pollinated pistil ?

(b) How many microscope mother cells would minimally be required to produce requisite number of pollen grains ?

(c) How many pollen grains must have minimally pollinated the carple ?

(d) How many male gametes would have used to produce these 200 viable seeds ?

(e) How many megaspore mother cells were required in this process ?

Name the part of the flower which the tassels of the corn- cob represent.

Make a list of any three outbreeding devices that flowering plants have developed and explain how they help to encourage cross-pollination.

Why angiosperm anthers are called dithecous?

What are chasmogamous flowers?

Can cross-pollination occur in cleistogamous flowers? Give reasons for your answer.

Mention two strategies that evolved to prevent self-pollination in flowers.

What is self-incompatibility?

Why does self-pollination not lead to seed formation in self-incompatible species?

What is the bagging technique?

What is meant by emasculation?

Find out through internet and popular science articles whether animals other than man have self-consciousness.

List 10 modern-day animals and using the internet resources link it to a corresponding ancient fossil. Name both.