Biochemistry Mcqs


Which of the following catalyzes the cutting of PIP2 into 2 moles of IP3 and diacylglycerol in cell signaling?

A) Lipokinase B) Phosphokinase C
C) Phosphodiesterase C D) Phospholipase C
Answer & Explanation Answer: D) Phospholipase C

Explanation: PLC also named phospholipase grabs onto PIP2 and cuts it into diacylglycerol and IP3.

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Which of the following is a hypertonic solution?

A) 0.45% sodium chloride B) Oceans
C) Red blood cells placed in fresh water D) Freshwater habitats
Answer & Explanation Answer: B) Oceans

Explanation: Many marine animals’ extracellular fluid is hypertonic to sea water/oceans. By regularly evacuating salt water, these marine species escape the challenge of hyper tonicity.

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Which of the following enzyme is secreted by the pancreas?

A) Myoglobin B) Cytochrome c
C) Ribonuclease D) Lysozyme
Answer & Explanation Answer: C) Ribonuclease

Explanation: The pancreas secretes ribonuclease into the small intestine, where it catalyses the hydrolysis of specific bonds in ingested ribonucleic acids.

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Which of the following regulatory sequence allows transcription to continue?

A) Sequence 4 B) Sequence 1
C) Sequence 2 D) Sequence 3
Answer & Explanation Answer: C) Sequence 2

Explanation: A tryptophan-sensitive mechanism requires regulatory sequence 1.
Sequence 2 is a complementary sequence to sequence 3.
Attenuating transcription is the purpose of Sequence 4.

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Which of the following bacterial operon is not controlled by attenuation?

A) Histidine B) Leucine
C) Arabinose D) Tryptophan
Answer & Explanation Answer: C) Arabinose

Explanation: Arabinose is a carbohydrate.

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Which of the following are the structural motifs that mediate protein-protein interactions?

A) Zinc finger B) Helix-turn-helix
C) Homeodomain D) Leucine zipper and basic helix-loop-helix
Answer & Explanation Answer: D) Leucine zipper and basic helix-loop-helix

Explanation: Not only do regulatory proteins have domains for DNA binding, but they also have domains for protein-protein interactions. DNA-binding domains include the homeodomain, zinc finger, and helix-turn-helix.

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How many amino acid residues are there in ubiquitin?

A) 70 B) 72
C) 74 D) 76
Answer & Explanation Answer: D) 76

Explanation: One of the most highly conserved proteins is known as ubiquitin (76 amino acid residues).

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Which of the following inactivates the 60S subunit of eukaryotic ribosomes?

A) Ricin B) Chloramphenicol
C) Cycloheximide D) Diphtheria toxin
Answer & Explanation Answer: A) Ricin

Explanation: By depurination of particular adenosine in 23S rRNA, ricin inactivates the 60S component of eukaryotic ribosomes.

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