Science (English Medium) Class 12 - CBSE Important Questions

Non viral and non vector methods are sometimes used to transfer genes or alien DNA into a plant cell. Explain one such method used in genetic engineering.

State the principle involved in separation of DNA fragments using gel electrophoresis.

How are DNA fragments visualised once they are separated by gel electrophoresis?

Identify the activity of endonuclease and exonuclease in the given image.

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.

Explain enzyme – replacement therapy to treat adenosine deaminase deficiency. Mention two disadvantages of this procedure.

Why do children cured by enzyme-replacement therapy adenosine deaminase deficiency need periodic treatment?

Write the function of adenosine deaminase enzyme.

Expand the Given and mention one application of each:

PCR

Why a transgenic animals so called?

Explain the role of transgenic animals in (i) Vaccine safety and (ii) Biological products with the help of an example each.

Suggest any two possible treatments that can be given to a patient exhibiting adenosine deaminase deficiency.

State the cause of ADA deficiency in humans.Mention a possible cure for an ADA deficiency patient.

Expand the Given and mention one application of each:

ELISA

What is gene therapy? Name the first clinical case in which it was used.

Why does Bt toxin not kill the bacterium that produces it, but kill the insect that ingests it?

Give a schematic representation of the transformation of a pro-insulin into insulin.

Write any two biochemical/molecular diagonostic procedures for early detection of viral infection. Explain the principle of any one of them.

Describe the steps that are followed during secondary treatment of sewage.

Answer the following question.
Describe the roles of heat, primers, and the bacterium Thermus aquaticus in the process of PCR.