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

Differentiate between Euchromatin and Heterochromatin.

Represent diagrammatically three kinds of age-pyramids for human populations.

How does an age pyramid for human population at given point of time helps the policy-makers in planning for future.

Name the transcriptionally active region of chromatin in a nucleus.

"Analysis of age-pyramids for human population can provide important inputs for long-term planning strategies." Explain.

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.

In which way have microbes played a major role in controlling diseases caused by harmful bacteria?

Name any two species of fungus, which are used in the production of the antibiotics.

Find out the name of the microbes from which cyclosporin A (an immunosuppressive drug) and statins (blood cholesterol lowering agents) are obtained.

Arrange the following in the decreasing order (most important first) of their importance for the welfare of human society. Give reasons for your answer.

Biogas, Citric acid, Penicillin and Curd

Make a chart (with diagrammatic representation) showing a restriction enzyme, the substrate DNA on which it acts, the site at which it cuts DNA and the product it produces.

Do eukaryotic cells have restriction endonucleases? Justify your answer.

Collect 5 examples of palindromic DNA sequences. Better try to create a palindromic sequence by following base-pair rules.

Explain briefly:

Restriction enzymes and DNA

Distinguish between exonuclease and endonuclease.

List the attributes that populations but not individuals possess.