Science (English Medium) इयत्ता १२ - CBSE Question Bank Solutions for Biology

Two organisms occupying a particular geographical area (say desert) show similar adaptive strategies. Taking examples, describe the phenomenon.

In the textbook you came across “Three Mile Island and Chernobyl disasters associated with accidental leakage of radioactive wastes.” In India we had Bhopal gas tragedy. It is associated with which of the following?

Observe the figure A and B given below and answer the following questions

A	B

1. The power generation by the above two methods is non-polluting True/False.
2. List any two applications of solar energy
3. What is a photovoltaic cell?

Trace the development of a megaspore mother cell to the formation of a mature embryo sac in a flowering plant.

Explain the monosporic development of the embryo sac in the ovule of an angiosperm.

Draw a diagram of the mature embryo sac of an angiospermic ovule and label any four parts in it.

Practise drawing various animals and plants.

Write the probable differences in eating habits of Homo habilis and Homo erectus.

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?

Mention any three characteristics of Neanderthal man that lived in near east and central Asia.

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?