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

The structure below shows pUC18, which is similar to pBR322 in its function. However, they differ in some of their restriction sites and the number of ori. The ori number for pBR322 is approximately 20.

1. How are puc18 and pBR322 used in biotechnological studies?
   OR
   What will be the impact if the ori in the above structure gets damaged?
2. The lac z gene has many recognition sites. Study the segment of DNA given below and answer the questions.
   5’... ATC GTA AAG CTT CAT…3’
   3’... TAG CAT TTC GAA GTA…5’
   i) Applying your knowledge of palindrome sequences identify and mark the possible region where the restriction enzyme X will act.
   ii) Restriction enzyme Y was used to extract a gene of interest from a plant. This gene needs to be inserted in the given DNA segment which has been treated with restriction enzyme X. Will there be a successful recombination? Explain with a reason.
3. Which one of the two (pUC18 and pBR322) would you prefer for biotechnological studies? Justify.

(a) Name the two growth models that represent population growth and draw the respective growth curves they represent.

(b) State the basics for the difference in the shape of these curves

(c) Which one of the curves represents the human population growth at present? Do you think such a curve is sustainable? Give reason in support of your answer.

Explain with the help of a suitable example the naming of a restriction endonuclease.

Construct an age pyramid which reflects a stable growth status of human population.

How are 'sticky ends' formed on a DNA strand? Why are they so called? 

Study the graph given below and answer the questions that follow :

(i) Write the status of food and space in the curves (a) and (b).
(ii) In the absence of predators, which one of the two curves would appropriately depict the prey population?
(iii) Time has been shown on X-axis and there is a parallel dotted line above it. Give the significance of this dotted line

Why is the enzyme cellulase needed for isolating genetic material from plant cells and not form the animal cells?

Mention the difference in the mode of action of exonuclease and endonuclease.

Why are the fruit juices bought from market clearer as compared to those made at home?

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.

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?