Biochemistry Past Paper MCQs | Batch 48 First Online Test 1st Year | mosaicbro.com
Biochemistry Past Paper MCQs | Batch 48 First Online Test 1st Year
This is series of Past Paper MCQs series of Biochemistry.
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22
What is the molecular weight of water?
Correct Answer:D
Explanation:
Water (H2O) has a molecular weight of 18 g/mol (1 + 1 + 16 from two hydrogens and one oxygen). This is a fundamental constant in stoichiometry and solution chemistry.
23
Minimum number of carbons required for a monosaccharide’s?
Correct Answer:C
Explanation:
Monosaccharides must have at least three carbons to form a sugar (e.g., trioses like glyceraldehyde or dihydroxyacetone). Fewer carbons cannot form the carbonyl and hydroxyl groups characteristic of sugars.
24
Specific gravity of lipids as?
Correct Answer:C
Explanation:
Lipids have a specific gravity of ~0.8, meaning they are less dense than water (specific gravity 1.0). This explains why fats float in aqueous solutions, such as in lipid droplets within cells.
25
Which of the following vitamin is synthesize from tryptophan?
Correct Answer:C
Explanation:
Niacin (Vitamin B3) can be synthesized from tryptophan via the kynurenine pathway. Approximately 60 mg of tryptophan yields 1 mg of niacin, though this is inefficient compared to dietary intake.
26
In mammalian liver, conversion of coproporphyringen III to protoporphyringen IX requires the presence of?
Correct Answer:A
Explanation:
Coproporphyrinogen III is converted to protoporphyrinogen IX by the enzyme coproporphyrinogen oxidase, which requires molecular oxygen (O2) and releases CO2. This step occurs in the mitochondria during heme synthesis.
27
As the pKa of an acid increase, the acid will be?
Correct Answer:B
Explanation:
pKa is inversely related to acid strength. Higher pKa values indicate weaker acids, as they dissociate less in solution (e.g., acetic acid, pKa 4.76, is weaker than HCl, pKa -6).
28
Biochemical reactions and proper functioning of organelles takes place in?
Correct Answer:A
Explanation:
The cytoplasm houses metabolic pathways (e.g., glycolysis), ribosomes for protein synthesis, and organelles like mitochondria. It provides the aqueous environment necessary for biochemical reactions.