The discovery of the enzyme 'restriction endonuclease' was a milestone in biotechnology. The first such enzyme was isolated by: MCQ with Answer and Explanation

The discovery of the enzyme 'restriction endonuclease' was a milestone in biotechnology. The first such enzyme was isolated by:
A. Watson and Crick
B. Paul Berg
C. Hamilton O. Smith, Kent W. Wilcox, and Thomas J. Kelly
D. Kary Mullis
Answer: Option C
Solution (By JKSSB Mock Tests)
While restriction enzymes were first observed by Linn and Arber, the first Type II restriction endonuclease (HindII), which is the type used in genetic engineering because it cuts at specific recognition sites, was isolated and characterized by Hamilton O. Smith, Kent W. Wilcox, and Thomas J. Kelly in 1970 from Haemophilus influenzae. For this discovery, Smith shared the Nobel Prize in Physiology or Medicine in 1978. Kary Mullis invented PCR.

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Practice More Biology Questions

Question #1
Consider statements about scientists: 1. Robert Hooke discovered the cell. 2. Louis Pasteur disproved spontaneous generation. 3. Alexander Fleming discovered the structure of DNA. Which are correct?
A. 1, 2 and 3
B. 1 and 2 only
C. 2 and 3 only
D. 1 and 3 only

Correct Answer: Option B


Explanation:
Robert Hooke first observed and coined the term 'cell' in 1665 using cork tissue. Louis Pasteur definitively disproved the theory of spontaneous generation using his swan-neck flask experiment. Alexander Fleming discovered the antibiotic penicillin, not the structure of DNA; that was elucidated by Watson and Crick. Thus, statements 1 and 2 are correct.

This question belongs to: Science Biology
Question #2
Consider statements about plant biology: 1. Phototropism is growth towards light. 2. Geotropism is growth in response to gravity. 3. Thigmotropism is growth in response to water. Which are correct?
A. 1 and 3 only
B. 1, 2 and 3
C. 2 and 3 only
D. 1 and 2 only

Correct Answer: Option D


Explanation:
Phototropism is the directional growth of a plant organ in response to light, typically positive in shoots. Geotropism (gravitropism) is the growth response to gravity, with roots showing positive geotropism (growing down) and shoots negative geotropism (growing up). Thigmotropism is the growth response to touch or physical contact, seen in climbing plants like vines, not water (which is hydrotropism). Thus, statements 1 and 2 are correct.

This question belongs to: Science Biology
Question #3
The condition caused by the deficiency of ADH leading to excessive dilute urine is:
A. Glycosuria
B. Uremia
C. Diabetes insipidus
D. Diabetes mellitus

Correct Answer: Option C


Explanation:
Diabetes insipidus results from insufficient ADH or kidney response, causing polyuria and polydipsia with dilute urine. Diabetes mellitus is hyperglycemia.

This question belongs to: Science Biology