Science (English Medium) इयत्ता १२ - CBSE Important Questions for Biology

A cell-free method of amplifying DNA first developed in the mid 1980's revolutionised the field of biotechnology, Name the method and explain the basic steps of the technique involved.

Farmers are often suggested to use the following organism in their crop land so as to improve the soil fertility. Explain.

Rhizobium

Farmers are often suggested to use the following organism in their crop land so as to improve the soil fertility. Explain.

Anabaena 

Given below are the list of the commercially important products and their source organisms. Select the option that gives the correct matches. 

Retroviruses have no DNA. However, the DNA of the infected host cell does possess viral DNA. How is it possible?

Rearrange the following in the correct sequence to accomplish an important biological reaction:

(a) In vitro synthesis of copies of DNA of interest

(b) Chemically synthesized oligonucleotides

(c) Enzyme DNA-polymerase

(d) Complementary region of DNA

(e) Genomic DNA template

(f) Nucleotides provided

(g) Primers

(h) Thermostable DNA-polymerase (from Thermus aquaticus)

(i) Denaturation of ds-DNA

Mention the type of host cells suitable for the gene guns to introduce an alien DNA.

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

Suggest and describe a technique to obtain multiple copies of a gene of interest in vitro.

Draw a labelled sketch of sparged-stirred-tank bioreactor. Write its application.

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

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

Write the steps you would suggest to be undertaken to obtain a foreign-gene-product.

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'

Given below is the stepwise schematic representation of the process of electrophoresis. Identify the 'alphabets' representing 

1. Anode end
2. smallest/lightest DNA strand in the matrix
3. Agarose gel

What is elution?

State the importance of elution in this process.

Read the paragraph given below and answer and questions that follow:

1. Taq polymerase after its discovery replaced E.coli DNA polymerase in PCR technique. Explain giving reasons why was the need felt for the change?
2. What is a primer and its importance in PCR?
3. Write the importance of PCR as a diagnostic tool.

Read the following paragraph and answer the questions that follow:

1. Name the human disease for which the gene therapy was used for the first time.
2. Explain the steps of gene therapy carried to cure the disease using the lymphocytes of the patient. Why is this therapy not a permanent cure of the disease?
3. Write the possible permanent cure of the disease by the gene therapy that is in progress.