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

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?

Name the drug a patient who has undergone a successful organ transplant, has to take all his/her life.

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.

Given below is an equation describing the Species-Area relationship between species richness and area for a wide variety of taxa as angiosperm plants, birds, bats etc. S = CA^z

1. Give a graphical representation of the given equation showing Species-Area relationship.
2. What does 'S' represent in the given equation?
3. What is the value of 'Z' (regression coefficient) for frugivorous birds and mammals in the tropical forests of different continents?

How does a gene therapy involving direct modification of the cells, in order to achieve a therapeutic goal is used in the treatment of ADA deficiency? Explain.

A host cell must be made competent, before it is able to receive an rDNA. Justify.

State the most important contribution of the following microbes for human welfare:

Monascus purpureus

State the most important contribution of the following microbes for human welfare:

Trichoderma Polysporum

Explain how recombinant human insulin was prepared in 1983 by Eli Lily an American company.

Write the inference drawn by Alexander von Humboldt after his extensive explorations of South American jungle.

Study the graph given below:

As per Alexander von Humboldt, what do the symbols S, A, Z and C in the graph stand for, in respect of a species and area relationship?

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.

Given below is the restriction site of a restriction endonuclease Pst-I and the cleavage sites on a DNA molecule.

\[\ce{5' C - T - G - C - A \overset{\downarrow}{-}{G 3'}}\]

\[\ce{3' G\underset{\uparrow}{-} A - C - G - T - C 5'}\]

Choose the option that gives the correct resultant fragments by the action of the enzyme Pst-I.

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

Name and explain a surgical contraceptive method that can be adopted by the male partner of a couple.

'EcoRI' has played a very significant role in rDNA technology.

1. Explain the convention for naming EcoRI.
2. Write the recognition site and the cleavage sites of this restriction endonuclease.

What are the protruding and hanging stretches of DNA produced by these restriction enzymes called? Describe their role in the formation of rDNA.