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

1. Give an example of a genus of fungi that forms mycorhizal association with plants. 
2. How does the plant derive benefits from this association?

The aeration tank of a sewage treatment plant is not functioning properly. Explain in detail the impact of this on the treatment of sewage and BOD of the effluent.

A farmer grew 2 varieties of corn crops in fields A and B. He grew normal corn crops in field A and GM corn crops in field B. He observed corn borers attacked only in field A. To control it, spores of Bt were sprayed in field A.

1. Name the gene in the spores responsible for the control of this pest.
2. What effect will the spores of Bt have on the insect pest?
3. How has field B developed resistance against this pest?

Name the selectable markers in the cloning vector pBR322. Mention the role they play.

State how has Agrobacterium tumifaciens been made a useful cloning vector to transfer DNA to plant cells.

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.

State the role of DNA ligase in biotechnology.

Explain the work carried out by Cohen and Boyer that contributed immensely in biotechnology.

Name the genes responsible for making Bt cotton plants resistant to bollworm attack. How do such plants attain resistance against bollworm attacks? Explain.

Draw a schematic sketch of pBR 322 plasmid and label the following in it:

(a) Any two restriction sites.

(b) Ori and rop genes.

(c) An antibiotic resistant gene.

Distinguish between exonuclease and endonuclease.

How does restriction endonuclease function?

State the importance of using a bioreactor.

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’ ?