The subunits of 80S ribosomes in eukaryotes are: MCQ with Answer and Explanation

The subunits of 80S ribosomes in eukaryotes are:
A. 50S + 30S
B. 30S + 50S
C. 60S + 40S
D. 40S + 60S
Answer: Option D
Solution (By JKSSB Mock Tests)
Eukaryotic ribosomes are 80S and composed of a small 40S subunit and a large 60S subunit. Prokaryotic ribosomes are 70S with 30S and 50S subunits. The S (Svedberg) value is a measure of sedimentation rate, not simply additive. Both ribosome types synthesize proteins, but the structural difference allows selective antibiotic targeting (e.g., streptomycin acts on 70S).

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Practice More Biology Questions

Question #1
Consider statements about plant stems: 1. Nodes are the regions where leaves arise. 2. Internodes are the regions between nodes. 3. All stems grow underground. Which are correct?
A. 2 and 3 only
B. 1 and 2 only
C. 1, 2 and 3
D. 1 and 3 only

Correct Answer: Option B


Explanation:
The stem is characterized by the presence of nodes, which are the junctions where leaves and buds arise, and internodes, the segments between two nodes. While some stems are modified to grow underground (like potatoes or onions) for storage or perennation, the primary and most common form of the stem is aerial, growing above the ground. Statements 1 and 2 are correct.

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Question #2
The disease caused by the deficiency of vitamin B₃ (niacin) is characterized by:
A. Night blindness
B. Bone deformities
C. Dermatitis, diarrhea, dementia
D. Bleeding gums

Correct Answer: Option C


Explanation:
Pellagra (niacin deficiency) presents with the three D's: dermatitis, diarrhea, and dementia. Bleeding gums is scurvy (vitamin C), bone deformities rickets (vitamin D), night blindness vitamin A deficiency.

This question belongs to: Science Biology
Question #3
The 'Hormone Galanin' is a neuropeptide widely distributed in the central nervous system and the gastrointestinal tract. Its functions include:
A. Increasing appetite
B. Stimulating gastric acid secretion
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D. Inhibiting insulin and glucagon release, and inhibiting gastric emptying and intestinal motility

Correct Answer: Option D


Explanation:
Galanin is a 29-amino acid neuropeptide that is co-localized with several other neurotransmitters and hormones. In the central nervous system, it is involved in various functions, including the inhibition of acetylcholine release and modulation of pain. In the gastrointestinal tract and pancreas, its primary functions are inhibitory: it inhibits the release of both insulin and glucagon from the pancreatic islets, inhibits gastric emptying and gastric acid secretion, and generally inhibits intestinal motility and secretion. It acts to slow down digestion and nutrient absorption.

This question belongs to: Science Biology