This set of Class 12 Biology Chapter 11 Multiple Choice Questions & Answers (MCQs) focuses on “Tools of Recombinant DNA Technology: Restriction Enzymes”.
1. From which organism was the first restriction enzyme isolated?
a) Escherichia coli
b) Salmonella typhimurium
c) Bacillus cereus
d) Staphylococcus aureus
Explanation: The restriction enzymes are molecular scissors that cleave the DNA at specific recognition sites. They were first isolated from Escherichia coli in the year 1963.
2. In genetic engineering, restriction enzymes cleave the DNA at a specific site known as _____
Explanation: Restriction enzymes cleave the DNA at a specific sequence known as recognition sequence. These sequences are highly specific for each enzyme.
3. Restriction enzymes are also known as _________
d) restriction endonucleases
Explanation: Restriction enzymes are also known as restriction endonucleases or restrictase. They are chemical knives (scissors) used in genetic engineering or recombinant DNA technology.
4. _____ was the first restriction endonuclease was isolated and characterized.
c) Hind II
d) Sma I
Explanation: Hind II was the first restriction endonuclease to be isolated and characterized. It cuts the DNA by recognizing a specific sequence of six base pairs. It was isolated from the bacteria called Haemophilus influenzae.
5. Restriction enzymes belong to a larger class of enzymes called ______
Explanation: Restriction enzymes belong to a larger class of enzymes called nucleases. There are two types of nucleases. They are: exonucleases and endonucleases.
6. The _______ in DNA are base pair sequences that are the same when read forward or backward from a central axis of symmetry.
c) termination sequences
d) amino acids
Explanation: Palindromes are a group of letters that form the same words when read forward (left to right) or backward (right to left). For example: NAYAN, MALAYALAM, etc.
7. Fragments of DNA formed after treatment with endonucleases are separated by the technique of _______
a) polymerase chain reaction
b) gene amplification
d) gel electrophoresis
Explanation: DNA is a charged molecule. When fragmented, it can be separated by the technique called gel electrophoresis. It is a technique in which the molecules are separated based on the charge present on that molecule.
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