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

Which of the following is not required in the preparation of a recombinant DNA molecule?

The most important feature in a plasmid to serve as a vector in gene cloning experiment is ______.

Who among the following was awarded the Nobel Prize for the development of PCR technique?

What is the significance of adding proteases at the time of isolation of genetic material (DNA)?

Name a recombinant vaccine that is currently being used in vaccination programme.

What is meant by gene cloning?

Both a wine maker and a molecular biologist who had developed a recombinant vaccine claim to be biotechnologists. Who in your opinion is correct?

A recombinant DNA molecule was created by ligating a gene to a plasmid vector. By mistake, an exonuclease was added to the tube containing the recombinant DNA. How does this affect the next step in the experiment i.e. bacterial transformation?

What would happen when one grows a recombinant bacterium in a bioreactor but forget to add antibiotic to the medium in which the recombinant is growing?

What is the expanded form of IUCN?

Why are the conventional methods not suitable for the assessment of biodiversity of bacteria?

What could be the possible explanation for greater vulnerability of amphibians to extinction as compared to other animal groups?

How do scientists extrapolate the total number of species on Earth?

(a) List two advantages of using bacteria for such biotechnological studies?

(b) For amplification of the gene of interest PCR was carried out. The PCR was run with the help of polymerase which was functional only at a very low temperature. How will this impact the efficiency of the PCR? Justify.

(c) If such bacteria are sprayed on water bodies with oil spills, how will this have a positive or negative effect on the environment? Discuss.

Given below is a 'pie chart' representing the global biodiversity:

Proportionate number of species of major taxa.

1. Identify (X) and (Y) in the given 'pie chart'.
2. "Extinction of species across taxa are not random." Which group amongst the vertebrates is more vulnerable to extinction?
3. Give one example of each of the recent extinctions of species in Russia, Mauritius and Australia.

Cloning of genes, play a very significant role in genetic engineering, helping the transfer of desirable foreign genes into different hosts. The scientists, to make this process easier and effective are creating engineered vectors in such a way that they help easy linking of foreign DNA and selection of recombinants from non-recombinants. 'pBR322' is one such engineered vectors developed by scientists. A diagram of an engineered vector pBR322 is given below:

1. Name the host for this cloning vector.
2. Identify 'Rop' and 'Ori' in the diagram from 'U', 'V', 'W', 'X', 'Y' and 'Z'. Write their functions.
3. Draw the fragments that will be formed by the action of 'Z' (marked in the diagram) on the specific site of the DNA segment given below:
   5' --- GTACGAATCCTGA --- 3'
   3' --- CATGCTTAGGACT --- 3'

Describe the dihybrid cross upto F₂ generation as conducted by Gregor Mendel using pure lines of Garden Pea for characters-seed shape and seed colour.

A short piece of DNA, having 20 base pairs, was analyzed to find the number of nucleotide bases in each of the polynucleotide strands. Some of the results are shown in the table.

How many nucleotides containing Adenine were present in strand 2?

What is the smallest part of a DNA molecule that can be changed by a point mutation?

Give three reasons as to why the prokaryotes are not given any figures for their diversity by ecologists.