In genetics, the '5' cap' is a modified guanine nucleotide added to the 5' end of eukaryotic mRNA. Its primary functions include: MCQ with Answer and Explanation

Question

In genetics, the '5' cap' is a modified guanine nucleotide added to the 5' end of eukaryotic mRNA. Its primary functions include:

A. Terminating transcription

B. Adding the poly-A tail

C. Splicing out introns

D. Protecting the mRNA from degradation and facilitating ribosome binding for translation initiation

Answer: Option D

Solution (By JKExamLibrary)

The 5' cap is a specially altered nucleotide (7-methylguanosine) attached via a 5'-5' triphosphate linkage to the 5' end of a eukaryotic mRNA molecule shortly after transcription begins. Its primary functions are to protect the nascent mRNA from degradation by 5' exonucleases, to facilitate the export of the mature mRNA from the nucleus to the cytoplasm, and, crucially, to be recognized by the eukaryotic initiation factor 4E (eIF4E), which is essential for recruiting the ribosome to the mRNA to initiate translation.

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The microorganism that causes food poisoning from improperly canned foods is:

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C. Escherichia coli

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Correct Answer: Option A

Explanation:
Clostridium botulinum, an anaerobic spore-forming bacterium, produces a potent neurotoxin causing botulism, often from improperly canned low-acid foods. Salmonella and E. coli cause gastroenteritis from contaminated food/water, Staphylococcus aureus produces enterotoxins causing acute vomiting. Botulism can be fatal without antitoxin.

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The biodiversity hotspot concept was introduced by:

A. Alexander von Humboldt

B. Charles Darwin

C. Norman Myers

D. E.O. Wilson

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Correct Answer: Option C

Explanation:
Norman Myers introduced the concept of biodiversity hotspots in 1988—regions with high endemic species and significant habitat loss (≥70% original vegetation lost). Examples: Western Ghats, Indo-Burma. Conservation efforts prioritize these areas. Darwin contributed evolution, Humboldt to biogeography, E.O. Wilson is known for sociobiology and biodiversity studies. Hotspots cover only 2.4% of Earth's land but hold >50% of plant species.

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Question #3

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Assertion (A): Bacteria can be killed by antibiotics like penicillin.
Reason (R): Penicillin inhibits the synthesis of bacterial cell wall.

A. A false, R true.

B. A true, R false.

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D. Both A and R are true, and R is the correct explanation.

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Correct Answer: Option D

Explanation:
Penicillin targets the transpeptidase enzyme, blocking peptidoglycan cross-linking, leading to cell lysis. This is the mechanism, so R correctly explains A.

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