MCQ 41:
Which of the following is a storage form of glucose in animals?
A) Cellulose
B) Starch
C) Glycogen
D) Chitin
Answer: C) Glycogen
Explanation: Glycogen is the storage form of glucose in animals, primarily found in the liver and muscle tissues. Cellulose and starch are forms of carbohydrates in plants, while chitin is a structural polysaccharide in fungi and exoskeletons of arthropods.
MCQ 42:
Which amino acid contains an aromatic ring?
A) Valine
B) Glycine
C) Phenylalanine
D) Proline
Answer: C) Phenylalanine
Explanation: Phenylalanine contains an aromatic ring in its side chain, making it an aromatic amino acid. Valine, glycine, and proline do not have aromatic structures.
MCQ 43:
Which of the following vitamins is fat-soluble?
A) Vitamin B12
B) Vitamin C
C) Vitamin A
D) Vitamin B6
Answer: C) Vitamin A
Explanation: Vitamin A is a fat-soluble vitamin, while vitamins B12, C, and B6 are water-soluble. Fat-soluble vitamins are stored in body fat and can be utilized as needed.
MCQ 44:
What type of interaction stabilizes the tertiary structure of proteins?
A) Peptide bonds
B) Hydrogen bonds
C) Ionic interactions
D) All of the above
Answer: D) All of the above
Explanation: The tertiary structure of proteins is stabilized by various interactions, including peptide bonds, hydrogen bonds, ionic interactions, hydrophobic interactions, and disulfide bridges.
MCQ 45:
Which of the following is a component of ATP?
A) Ribose, adenine, and three phosphate groups
B) Deoxyribose, thymine, and three phosphate groups
C) Ribose, guanine, and two phosphate groups
D) Ribose, adenine, and one phosphate group
Answer: A) Ribose, adenine, and three phosphate groups
Explanation: ATP (adenosine triphosphate) consists of ribose sugar, adenine base, and three phosphate groups. It serves as the main energy currency of the cell.
MCQ 46:
Which of the following is a characteristic of enzymes?
A) They can be denatured by changes in pH and temperature.
B) They change the equilibrium of the reaction.
C) They are always proteins.
D) They require coenzymes for all reactions.
Answer: A) They can be denatured by changes in pH and temperature.
Explanation: Enzymes can be denatured by extreme changes in pH and temperature, which affect their structure and function. Not all enzymes are proteins (some are RNA), and they do not change the equilibrium of reactions.
MCQ 47:
What is the primary structure of DNA?
A) A double helix
B) A single strand
C) A linear sequence of nucleotides
D) A three-dimensional folded structure
Answer: C) A linear sequence of nucleotides
Explanation: The primary structure of DNA refers to its linear sequence of nucleotides, which includes the sugar, phosphate, and nitrogenous bases. The double helix is the secondary structure.
MCQ 48:
Which of the following carbohydrates is NOT digestible by humans?
A) Starch
B) Glycogen
C) Cellulose
D) Sucrose
Answer: C) Cellulose
Explanation: Humans cannot digest cellulose due to the beta-glycosidic bonds between glucose units. Starch and glycogen are digestible, and sucrose is a disaccharide that can be broken down.
MCQ 49:
Which process synthesizes ATP using a proton gradient across the inner mitochondrial membrane?
A) Glycolysis
B) Krebs cycle
C) Oxidative phosphorylation
D) Fermentation
Answer: C) Oxidative phosphorylation
Explanation: Oxidative phosphorylation synthesizes ATP using a proton gradient created by the electron transport chain across the inner mitochondrial membrane. Glycolysis and the Krebs cycle produce less ATP, while fermentation occurs in anaerobic conditions.
MCQ 50:
What type of bond links monosaccharides to form disaccharides?
A) Peptide bond
B) Glycosidic bond
C) Ionic bond
D) Hydrogen bond
Answer: B) Glycosidic bond
Explanation: Glycosidic bonds link monosaccharides together to form disaccharides and polysaccharides. Peptide bonds link amino acids, while ionic and hydrogen bonds play different roles in molecular interactions.
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