MCQ 11:
Which molecule serves as the primary energy currency of the cell?
A) DNA
B) RNA
C) ATP
D) GTP
Answer: C) ATP
Explanation: ATP (adenosine triphosphate) is known as the primary energy currency of the cell, providing energy for various cellular processes. DNA and RNA are nucleic acids, while GTP is another energy molecule, less commonly used than ATP.
MCQ 12:
Which of the following is NOT a function of carbohydrates?
A) Energy storage
B) Structural support
C) Enzyme catalysis
D) Cell recognition
Answer: C) Enzyme catalysis
Explanation: While carbohydrates play important roles in energy storage, structural support, and cell recognition, enzyme catalysis is primarily the role of proteins.
MCQ 13:
Which type of lipid is primarily responsible for forming the cell membrane?
A) Phospholipids
B) Steroids
C) Triglycerides
D) Waxes
Answer: A) Phospholipids
Explanation: Phospholipids are the main component of cell membranes, forming a bilayer that provides structure and regulates what enters and leaves the cell. Triglycerides are for energy storage, steroids have signaling roles, and waxes provide protection.
MCQ 14:
Which of the following biomolecules contains the genetic information of an organism?
A) RNA
B) Proteins
C) Lipids
D) Carbohydrates
Answer: A) RNA
Explanation: RNA carries genetic information in certain viruses and is also involved in protein synthesis. While DNA is the primary genetic material in most organisms, RNA also plays essential roles in genetics.
MCQ 15:
Which of the following amino acids contains a sulfur atom?
A) Cysteine
B) Glutamate
C) Aspartate
D) Serine
Answer: A) Cysteine
Explanation: Cysteine is the amino acid that contains a sulfur atom in its side chain, which allows it to form disulfide bonds, crucial for protein structure.
MCQ 16:
Which of the following is a function of nucleotides besides serving as building blocks for nucleic acids?
A) Energy transfer
B) Structural support
C) Catalytic activity
D) Insulation
Answer: A) Energy transfer
Explanation: Nucleotides like ATP are involved in energy transfer within the cell. They do not provide structural support or insulation, nor are they primarily involved in catalytic activity (which is the role of enzymes).
MCQ 17:
Which of the following molecules is a product of the hydrolysis of starch?
A) Cellulose
B) Sucrose
C) Maltose
D) Glucose
Answer: C) Maltose
Explanation: Hydrolysis of starch, a polysaccharide, results in maltose, which is a disaccharide made of two glucose units. Further hydrolysis of maltose can yield glucose.
MCQ 18:
Which of the following proteins has a quaternary structure?
A) Myoglobin
B) Hemoglobin
C) Insulin
D) Keratin
Answer: B) Hemoglobin
Explanation: Hemoglobin has a quaternary structure consisting of four polypeptide subunits. Myoglobin has a tertiary structure, insulin is a dimer (two chains), and keratin is primarily fibrous and forms a different type of structure.
MCQ 19:
What is the basic structural unit of proteins?
A) Nucleotides
B) Amino acids
C) Fatty acids
D) Monosaccharides
Answer: B) Amino acids
Explanation: Amino acids are the basic building blocks of proteins, linked by peptide bonds to form polypeptide chains. Nucleotides are the building blocks of nucleic acids, while fatty acids and monosaccharides are components of lipids and carbohydrates, respectively.
MCQ 20:
Which of the following is a feature of enzymes?
A) They increase the activation energy of reactions.
B) They are consumed in the reaction.
C) They are specific to substrates.
D) They function at any temperature.
Answer: C) They are specific to substrates.
Explanation: Enzymes are highly specific to their substrates and catalyze reactions without being consumed in the process. They lower the activation energy of reactions, and their activity can be affected by temperature.
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