The enzyme that catalyzes the conversion of pyruvate to lactic acid is: MCQ with Answer and Explanation

The enzyme that catalyzes the conversion of pyruvate to lactic acid is:
A. Pyruvate decarboxylase
B. Pyruvate kinase
C. Alcohol dehydrogenase
D. Lactate dehydrogenase
Answer: Option D
Solution (By JKSSB Mock Tests)
Lactate dehydrogenase (LDH) reduces pyruvate to lactate using NADH, regenerating NAD⁺ for glycolysis under anaerobic conditions. Pyruvate decarboxylase is in alcoholic fermentation, alcohol dehydrogenase converts acetaldehyde to ethanol, pyruvate kinase is in glycolysis.

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Practice More Biology Questions

Question #1
The process of converting mRNA information into a polypeptide chain is:
A. Translation
B. Replication
C. Transcription
D. Transduction

Correct Answer: Option A


Explanation:
Translation is the synthesis of a polypeptide chain at the ribosome, where the genetic code in mRNA is read by tRNA anticodons to assemble amino acids in the correct order. Transcription produces mRNA from DNA, replication duplicates DNA, transduction is gene transfer by viruses. Translation involves initiation, elongation, and termination factors.

This question belongs to: Science Biology
Question #2
Lysosomes are rich in which type of enzymes?
A. Isomerases
B. Oxidoreductases
C. Hydrolytic enzymes
D. Transferases

Correct Answer: Option C


Explanation:
Lysosomes contain about 40 types of hydrolytic enzymes (hydrolases) like proteases, lipases, nucleases, glycosidases, which digest macromolecules. They function in acidic pH (5.0). Oxidoreductases catalyze oxidation-reduction, transferases transfer groups, isomerases catalyze isomerization. Lysosomes are involved in autophagy, phagocytosis, and programmed cell death. Their rupture leads to autolysis, hence called 'suicide bags'.

This question belongs to: Science Biology
Question #3
The element that is the central atom in chlorophyll is:
A. Iron
B. Calcium
C. Cobalt
D. Magnesium

Correct Answer: Option D


Explanation:
Magnesium is the central atom in the porphyrin ring of chlorophyll, essential for light absorption in photosynthesis. Iron is in heme, calcium structural, cobalt in vitamin B₁₂.

This question belongs to: Science Biology