Updated for 2024. Biochem - Module 4 Exam
Questions with 100% Correct Answers.
Guaranteed A+ Pass.
1. What is the role of ATP in cellular metabolism?
Answer: ATP (Adenosine Triphosphate) serves as the primary energy currency in the cell. It provides the
energy needed for various cellular processes, including muscle contraction, active transport, and biochemical
reactions.
2. How do enzymes speed up biochemical reactions?
Answer: Enzymes act as biological catalysts by lowering the activation energy required for a reaction to
occur. They achieve this by binding to substrates and stabilizing the transition state, making it easier for the
reaction to proceed.
3. What is the difference between competitive and non-competitive enzyme inhibition?
Answer: In competitive inhibition, the inhibitor binds to the active site of the enzyme, directly competing
with the substrate. In non-competitive inhibition, the inhibitor binds to a different site on the enzyme
(allosteric site), changing the enzyme's shape and reducing its activity, regardless of substrate concentration.
4. Describe the primary structure of a protein.
Answer: The primary structure of a protein is the linear sequence of amino acids linked by peptide bonds.
This sequence is unique for each protein and determines its final three-dimensional structure and function.
5. What is glycolysis, and what are its end products?
Answer: Glycolysis is a metabolic pathway that breaks down one molecule of glucose (a 6-carbon sugar)
into two molecules of pyruvate (a 3-carbon compound), producing a net gain of two ATP molecules and two
NADH molecules. Glycolysis occurs in the cytoplasm of the cell and does not require oxygen.
6. Explain the role of the citric acid cycle (Krebs cycle) in cellular respiration.
Answer: The citric acid cycle, also known as the Krebs cycle, occurs in the mitochondria and is a key
component of cellular respiration. It oxidizes acetyl-CoA to produce carbon dioxide, NADH, FADH2, and
ATP. NADH and FADH2 generated in the cycle are used in the electron transport chain to produce a large
amount of ATP.
7. How does the structure of DNA differ from that of RNA?
Answer: DNA (deoxyribonucleic acid) is double-stranded, has deoxyribose as its sugar, and uses the bases
adenine, thymine, cytosine, and guanine. RNA (ribonucleic acid) is single-stranded, has ribose as its sugar,
and uses the bases adenine, uracil, cytosine, and guanine.
8. What is oxidative phosphorylation, and where does it occur?
Answer: Oxidative phosphorylation is the process by which ATP is produced in the mitochondria as a result
of the electron transport chain and chemiosmosis. Electrons are transferred from NADH and FADH2
through protein complexes, leading to the pumping of protons across the inner mitochondrial membrane,
creating a proton gradient. ATP is synthesized as protons flow back through ATP synthase.
, 9. Define allosteric regulation in enzymes.
Answer: Allosteric regulation involves the binding of a regulatory molecule (an effector) to an enzyme at a
site other than the active site, known as the allosteric site. This binding can either enhance (positive
regulation) or inhibit (negative regulation) the enzyme's activity, thereby controlling the rate of the
biochemical reaction.
10. What is the significance of the Michaelis-Menten constant (Km)?
Answer: The Michaelis-Menten constant (Km) is a measure of the substrate concentration at which the
reaction rate is half of its maximum velocity (Vmax). A low Km indicates high affinity of the enzyme for the
substrate, while a high Km indicates lower affinity.
11. Which Of The Following Monosaccharides Is Not An Aldose?
A. Erythrose
B. Dihydroxyacetone
C. Glucose
D. Glyceraldehyde
E. Ribose
Correct Answer. B. Dihydroxyacetone
12. When Two Monosaccharides Are Epimers:
A. They Differ Only In The Configuration About The Penultimate Carbon
B. One Is An Aldose, The Other A Ketose
C. They Differ Only In The Configuration About One Carbon Atom
D. They Form O-Glycosidic Bonds
E. They Are Oligosaccharides
Correct Answer. C. They Differ Only In The Configuration About One Carbon Atom
13. Which Pair Is Anomeric?
A. D-Glucose And D-Fructose
B. D-Glucose And L-Fructose
C. D-Glucose And L-Glucose
D. Alpha-D-Glucose And Beta-D-Fructose
E. Alpha-D-Glucose And Beta-D-Glucose
Correct Answer. E. Alpha-D-Glucose And Beta-D-Glucose
14. Lactose Is Made From Linking Galactose And Glucose. When This Happens:
A. A Polysaccharide Is Formed
B. Gas Is Eliminated
C. An Epimer Is Formed
D. An Anomeric Carbon Is Formed On Carbon-1
E. Lactose Forms By A Condensation Reaction
Correct Answer. E. Lactose Forms By A Condensation Reaction
15. Lactose Is Made From Linking Galactose And Glucose. When This Happens:
A. Gas Is Eliminated
B. An Anomeric Carbon Is Formed On Carbon-1
C. Water Is Released
Questions with 100% Correct Answers.
Guaranteed A+ Pass.
1. What is the role of ATP in cellular metabolism?
Answer: ATP (Adenosine Triphosphate) serves as the primary energy currency in the cell. It provides the
energy needed for various cellular processes, including muscle contraction, active transport, and biochemical
reactions.
2. How do enzymes speed up biochemical reactions?
Answer: Enzymes act as biological catalysts by lowering the activation energy required for a reaction to
occur. They achieve this by binding to substrates and stabilizing the transition state, making it easier for the
reaction to proceed.
3. What is the difference between competitive and non-competitive enzyme inhibition?
Answer: In competitive inhibition, the inhibitor binds to the active site of the enzyme, directly competing
with the substrate. In non-competitive inhibition, the inhibitor binds to a different site on the enzyme
(allosteric site), changing the enzyme's shape and reducing its activity, regardless of substrate concentration.
4. Describe the primary structure of a protein.
Answer: The primary structure of a protein is the linear sequence of amino acids linked by peptide bonds.
This sequence is unique for each protein and determines its final three-dimensional structure and function.
5. What is glycolysis, and what are its end products?
Answer: Glycolysis is a metabolic pathway that breaks down one molecule of glucose (a 6-carbon sugar)
into two molecules of pyruvate (a 3-carbon compound), producing a net gain of two ATP molecules and two
NADH molecules. Glycolysis occurs in the cytoplasm of the cell and does not require oxygen.
6. Explain the role of the citric acid cycle (Krebs cycle) in cellular respiration.
Answer: The citric acid cycle, also known as the Krebs cycle, occurs in the mitochondria and is a key
component of cellular respiration. It oxidizes acetyl-CoA to produce carbon dioxide, NADH, FADH2, and
ATP. NADH and FADH2 generated in the cycle are used in the electron transport chain to produce a large
amount of ATP.
7. How does the structure of DNA differ from that of RNA?
Answer: DNA (deoxyribonucleic acid) is double-stranded, has deoxyribose as its sugar, and uses the bases
adenine, thymine, cytosine, and guanine. RNA (ribonucleic acid) is single-stranded, has ribose as its sugar,
and uses the bases adenine, uracil, cytosine, and guanine.
8. What is oxidative phosphorylation, and where does it occur?
Answer: Oxidative phosphorylation is the process by which ATP is produced in the mitochondria as a result
of the electron transport chain and chemiosmosis. Electrons are transferred from NADH and FADH2
through protein complexes, leading to the pumping of protons across the inner mitochondrial membrane,
creating a proton gradient. ATP is synthesized as protons flow back through ATP synthase.
, 9. Define allosteric regulation in enzymes.
Answer: Allosteric regulation involves the binding of a regulatory molecule (an effector) to an enzyme at a
site other than the active site, known as the allosteric site. This binding can either enhance (positive
regulation) or inhibit (negative regulation) the enzyme's activity, thereby controlling the rate of the
biochemical reaction.
10. What is the significance of the Michaelis-Menten constant (Km)?
Answer: The Michaelis-Menten constant (Km) is a measure of the substrate concentration at which the
reaction rate is half of its maximum velocity (Vmax). A low Km indicates high affinity of the enzyme for the
substrate, while a high Km indicates lower affinity.
11. Which Of The Following Monosaccharides Is Not An Aldose?
A. Erythrose
B. Dihydroxyacetone
C. Glucose
D. Glyceraldehyde
E. Ribose
Correct Answer. B. Dihydroxyacetone
12. When Two Monosaccharides Are Epimers:
A. They Differ Only In The Configuration About The Penultimate Carbon
B. One Is An Aldose, The Other A Ketose
C. They Differ Only In The Configuration About One Carbon Atom
D. They Form O-Glycosidic Bonds
E. They Are Oligosaccharides
Correct Answer. C. They Differ Only In The Configuration About One Carbon Atom
13. Which Pair Is Anomeric?
A. D-Glucose And D-Fructose
B. D-Glucose And L-Fructose
C. D-Glucose And L-Glucose
D. Alpha-D-Glucose And Beta-D-Fructose
E. Alpha-D-Glucose And Beta-D-Glucose
Correct Answer. E. Alpha-D-Glucose And Beta-D-Glucose
14. Lactose Is Made From Linking Galactose And Glucose. When This Happens:
A. A Polysaccharide Is Formed
B. Gas Is Eliminated
C. An Epimer Is Formed
D. An Anomeric Carbon Is Formed On Carbon-1
E. Lactose Forms By A Condensation Reaction
Correct Answer. E. Lactose Forms By A Condensation Reaction
15. Lactose Is Made From Linking Galactose And Glucose. When This Happens:
A. Gas Is Eliminated
B. An Anomeric Carbon Is Formed On Carbon-1
C. Water Is Released
