The term 'operon' in genetics refers to: MCQ with Answer and Explanation

The term 'operon' in genetics refers to:
A. A single gene with multiple functions
B. A set of linked genes regulated by a single promoter
C. A viral DNA integrated into host genome
D. A DNA repair mechanism
Answer: Option B
Solution (By JKExamLibrary)
An operon is a functional unit of DNA in prokaryotes containing a cluster of genes under the control of a single promoter, transcribed as a single mRNA. Example: lac operon. It includes operator, promoter, and structural genes. Operons allow coordinate regulation. Eukaryotes generally lack operons.

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Practice More Biology Questions

Question #1
The plant response to touch, such as the closing of Mimosa pudica leaves, is:
A. Geotropism
B. Phototropism
C. Thigmonasty
D. Thigmotropism

Correct Answer: Option C


Explanation:
Thigmonasty (seismonasty) is a non-directional, rapid response to touch or vibration, exemplified by the drooping of Mimosa pudica leaves. Thigmotropism is directional growth towards/away from touch (e.g., tendrils). Phototropism is light-directed growth, geotropism gravity-directed.

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 excess growth hormone after puberty is:
A. Dwarfism
B. Acromegaly
C. Gigantism
D. Cretinism

Correct Answer: Option B


Explanation:
Acromegaly is the enlargement of bones and soft tissues due to overproduction of growth hormone in adults after growth plates have fused. Gigantism occurs in childhood, dwarfism GH deficiency, cretinism congenital hypothyroidism.

This question belongs to: Science Biology