Science (English Medium) Class 12 - CBSE Question Bank Solutions

Sketch and label stages in the development of the angiospermic female gametophyte from the functional megaspore.

In which way has the study of biology helped us to control infectious diseases?

List the three stages the annuals and biennial angiosperms have to pass through during their life cycle.

By taking two examples explain how has bio-fortification helped in improving food quality.

In a flowering plant a microspore mother cell produces four male gametophytes, while a megaspore mother cell forms only one female gametophyte. Explain.

Read the statement and answer the questions that follow.

A flower of brinjal has 520 ovules in its ovary. However, it produces a fruit with only 480 viable seeds.

(a) What could have prevented the rest of the 40 ovules from maturing into viable seeds? Explain giving a reason.

(b) Describe the development of a dicot embryo in a viable seed.

(c) Why certain angiospermic seed albuminous while others are exalbuminous? Explain.

A capsicum flower has 240 ovules in its ovary. But, it produces a fruit with only 180 viable seeds.
 

Name the following:  Any one inter-specific hybrid mammal.

Give an example of an angiosperm seed that has a perisperm. Name the part the perisperm develops from.

Explain the events upto double fertilisation after the pollen tube enters one of the synergids in an ovule of an angiosperm.
 

Bottled fruit juices are clearer as compared to those made at home. Explain.

A typical flower has ______ different kinds of whorl.

Science of cultivation, breeding, marketing and arrangement of flowers is called ______.

Fragrant flowers with well developed nectaries are an adaptation for ______.

The flower is the site of ______.

Pollen grains are well preserved as fossils because of the presence of ______

In a fertilized ovule, n, 2n, and 3n conditions occur respectively in ______

When an apparently healthy person is diagnosed as unhealthy by a psychiatrist, the reason could be that ______.  

The term ' health' is defined in many ways. The most accurate definition of health would be

Diseases are broadly grouped into infectious and non-infectious diseases. In the list given below, identify the infectious diseases.

1. Cancer
2. Influenza
3. Allergy
4. Small pox