MCQ 31:
Which of the following is a characteristic of unsaturated fatty acids?
A) They are solid at room temperature.
B) They contain one or more double bonds.
C) They are derived from animal fats.
D) They have higher melting points than saturated fats.
Answer: B) They contain one or more double bonds.
Explanation: Unsaturated fatty acids contain one or more double bonds between carbon atoms, making them usually liquid at room temperature. Saturated fats are solid at room temperature and typically come from animal sources.
MCQ 32:
Which of the following is a function of cholesterol in the cell membrane?
A) Energy storage
B) Hormone synthesis
C) Maintaining membrane fluidity
D) Genetic information storage
Answer: C) Maintaining membrane fluidity
Explanation: Cholesterol is a crucial component of cell membranes that helps maintain fluidity, allowing the membrane to remain flexible at various temperatures. It is also a precursor for steroid hormones but does not store energy or genetic information.
MCQ 33:
Which of the following molecules is a type of glycoprotein?
A) Insulin
B) Hemoglobin
C) Antibodies
D) Collagen
Answer: C) Antibodies
Explanation: Antibodies are glycoproteins that play a crucial role in the immune response. Insulin is a peptide hormone, hemoglobin is a protein that carries oxygen, and collagen is a structural protein.
MCQ 34:
Which component of nucleotides differs between DNA and RNA?
A) Sugar
B) Nitrogenous base
C) Phosphate group
D) All of the above
Answer: A) Sugar
Explanation: The sugar component differs between DNA (deoxyribose) and RNA (ribose). Both types of nucleotides contain phosphate groups and can have different nitrogenous bases (thymine in DNA vs. uracil in RNA).
MCQ 35:
What is the role of ribosomes in a cell?
A) Energy production
B) Protein synthesis
C) Lipid storage
D) DNA replication
Answer: B) Protein synthesis
Explanation: Ribosomes are the cellular machinery responsible for synthesizing proteins by translating mRNA into amino acid sequences. They do not directly participate in energy production, lipid storage, or DNA replication.
MCQ 36:
Which type of carbohydrate can be digested by humans?
A) Cellulose
B) Starch
C) Chitin
D) Glycogen
Answer: B) Starch
Explanation: Starch is a digestible carbohydrate found in plants, composed of glucose units. Humans cannot digest cellulose due to the beta-glycosidic bonds, and chitin is a structural polysaccharide in fungi and arthropods. Glycogen is digestible, but it is primarily a storage form in animals.
MCQ 37:
Which of the following is a nonpolar amino acid?
A) Aspartate
B) Glutamate
C) Phenylalanine
D) Lysine
Answer: C) Phenylalanine
Explanation: Phenylalanine is a nonpolar amino acid due to its hydrophobic side chain. Aspartate and glutamate are polar and negatively charged, while lysine is polar and positively charged.
MCQ 38:
What is the primary function of enzymes in biochemical reactions?
A) To decrease the reaction rate
B) To provide energy
C) To lower the activation energy
D) To change the products of the reaction
Answer: C) To lower the activation energy
Explanation: Enzymes catalyze reactions by lowering the activation energy required for the reaction to proceed, thereby increasing the reaction rate. They do not provide energy or alter the products of the reaction.
MCQ 39:
Which of the following fatty acids is essential and must be obtained from the diet?
A) Stearic acid
B) Palmitic acid
C) Linoleic acid
D) Myristic acid
Answer: C) Linoleic acid
Explanation: Linoleic acid is an essential fatty acid that humans must obtain from their diet. Stearic, palmitic, and myristic acids can be synthesized by the body.
MCQ 40:
Which of the following is a key characteristic of enzymes?
A) They can work in any environment.
B) They can be reused multiple times.
C) They are permanently altered after the reaction.
D) They increase the equilibrium constant of the reaction.
Answer: B) They can be reused multiple times.
Explanation: Enzymes can be reused multiple times after catalyzing a reaction, as they are not consumed in the process. They work under specific conditions and do not change the equilibrium constant.
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