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

Name the source of streptokinase. How does this bioreactor molecule function in our body?

Suggest a technique to a researcher who needs to separate fragments of DNA.

How are the following formed and involved in DNA packaging in a nucleus of a cell?

Differentiate between Euchromatin and Heterochromatin.

Name the transcriptionally active region of chromatin in a nucleus.

Name the enzymes that are used for the isolation of DNA from bacterial and fungal cells for recombinant DNA technology.

How does a restriction nuclease function? Explain

The following graph shows the species-area relationship. Answer the following questions as directed.

(a) Name the naturalist who studied the kind of relationship shown in the graph. Write the observations made by him.

(b) Write the situations as discovered by the ecologists when the value of ‘Z’
(Slope of the line) lies between:

1. 0.1 and 0.2
2. 0.6 and 1.2

What does ‘Z’ stand for?

(c) When would the slope of the line ‘b’ become steeper?

Name and describe the technique that helps in separating the DNA fragments formed by the use of restriction endonuclease

Explain, giving three reasons, why tropics show greatest levels of species diversity.

Draw a labelled diagram of the female reproductive system.

Write two major functions of ovary.

Name the function of the following:

Endometrium

Name the function of the following:

Sperm tail

Identify True/False statement. Correct false statement to make it true.

Presence or absence of hymen is not a reliable indicator of virginity or sexual experience.

How many eggs are released by a human ovary in a month? How many eggs do you think would have been released if the mother gave birth to identical twins? Would your answer change if the twins born were fraternal?

How many eggs do you think were released by the ovary of a female dog which gave birth to 6 puppies?

What are the suggested reasons for population explosion?

Is the use of contraceptives justified? Give reasons.

Removal of gonads cannot be considered as a contraceptive option. Why?