Science (English Medium) कक्षा १२ - CBSE Important Questions

Why is the coding sequence of an enzyme β-galactosidase a preferred selectable marker in comparison to the ones named above?

One of the major contributions of biotechnology is to develop pest-resistant varieties of cotton plants. Explain how it has been made possible.

Prepare a flow chart in formation of recombinant DNA by the action of restriction endonuclease enzyme EcoRI.

What is ‘Ori’ ? State its importance during cloning of a vector.

Explain the importance of ‘Selectable marker’, with the help of a suitable example.

Why should a bacterium be made ‘competent’ ?

Explain the role of ‘microinjection’ and ‘gene gun’ in biotechnology

Answer the following question.
β galactosidase enzyme is considered a better selectable marker. Justify the statement.

Answer the following question.
Expand ‘YAC’ and mention what it was used for.

Answer the following question.
Explain the significance of palindromic nucleotide sequence in the formation of recombinant DNA.

Answer the following question.
Write the use of restriction endonuclease in the formation of recombinant DNA.

What is the cell that receives a recombinant gene called?

Give a reason why :
Proteases are added during the isolation of DNA for genetic engineering.

Give a reason why :
Single cloning site is preferred in a vector.

How does the β-galactosidase coding sequence act as a selectable marker? Why is it a preferred selectable marker to antibiotic resistance genes? Explain.

In a pathological lab, a series of steps were undertaken for finding the gene of interest. Describe the steps, or make a flow chart showing the process of amplification of this gene of interest.

The figure below shows the structure of a plasmid.

A foreign DNA was ligated at BamH1. The transformants were then grown in a medium containing antibiotics tetracycline and ampicillin.

Choose the correct observation for the growth of bacterial colonies from the given table.

CTTAAG
GAATTC

1. What are such sequences called? Name the enzyme used that recognizes such nucleotide sequences.
2. What is their significance in biotechnology?

Carefully observe the given picture. A mixture of DNA with fragments ranging from 200 base pairs to 2500 base pairs was electrophoresed on agarose gel with the following arrangement.

(a) What result will be obtained on staining with ethidium bromide? Explain with reason.

(b) The above setup was modified and a band with 250 base pairs was obtained at X.

What change(s) were made to the previous design to obtain a band at X? Why did the band appear at position X?

(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.