Molecular Biology and Biochemistry |
Biological Molecules | 2026/2027 Academic
Year | Verified Exam Molecular Biology and
Biochemistry | Actual Q&A | Pre-Medical and
Life Sciences Students
Introduction
This comprehensive 65-question practice set covers the Molecular Biology
and Biochemistry curriculum focusing on Biological Molecules, including
Carbohydrates, Lipids, Proteins, Nucleic Acids, and key Laboratory
Techniques. The examination emphasizes the rigorous application of
biochemical principles, molecular structures, metabolic pathways, and the
systematic use of experimental methods to analyze biological
macromolecules. Learners are required to evaluate molecular structures,
metabolic functions, and the biochemical basis of life processes. Each item
includes a fully worked rationale, a distractor analysis clarifying why
incorrect options are wrong, and a reference to standard biochemistry and
molecular biology textbooks.
Domain 1: Carbohydrates & Glycobiology (Questions 1-13)
1. Dehydration synthesis leads to the formation of:
A. Monomers
B. Polymers
C. Water and polymers
D. None of the above
Answer: C
Rationale: Dehydration synthesis (also called condensation reaction) joins
monomers together to form polymers while releasing a molecule of water for
each bond formed. For example, monosaccharides join via glycosidic bonds to
form polysaccharides with the release of H₂O.
,Why Wrong: A - Dehydration synthesis consumes monomers to build polymers. B
- While polymers are formed, water is also produced, making C the complete
answer. D - Incorrect.
2. Which of the following is an example of a monosaccharide?
A. Fructose
B. Glucose
C. Galactose
D. All of the above
Answer: D
Rationale: Fructose, glucose, and galactose are all monosaccharides (simple
sugars) with the molecular formula C₆H₁₂O₆. Glucose and galactose are aldoses,
while fructose is a ketose.
Why Wrong: A, B, and C are each correct individually, but D is the most complete
answer as all three are monosaccharides.
3. Cellulose and starch are examples of:
A. Monosaccharides
B. Disaccharides
C. Lipids
D. Polysaccharides
Answer: D
Rationale: Both cellulose and starch are polysaccharides—complex
carbohydrates composed of many glucose monomers linked by glycosidic bonds.
Starch is the energy storage polysaccharide in plants, while cellulose is a
structural polysaccharide in plant cell walls.
Why Wrong: A - Monosaccharides are single sugar units. B - Disaccharides are
two sugar units linked together. C - Lipids are a different class of
macromolecules.
4. Lactose is a disaccharide formed by the formation of a ________ bond
between glucose and ________:
A. Glycosidic; lactose
, B. Glycosidic; galactose
C. Hydrogen; sucrose
D. Hydrogen; fructose
Answer: B
Rationale: Lactose (milk sugar) is a disaccharide consisting of glucose and
galactose linked by a β-1,4-glycosidic bond. The bond type is glycosidic, not
hydrogen, and the second monosaccharide is galactose.
Why Wrong: A - Lactose is the product, not the second monosaccharide. C -
Sucrose is glucose + fructose. D - Hydrogen bonds are not the primary linkage in
disaccharides.
5. Plant cell walls contain which of the following in abundance?
A. Starch
B. Cellulose
C. Glycogen
D. Lactose
Answer: B
Rationale: Plant cell walls are primarily composed of cellulose, a polysaccharide
made of β-1,4-linked glucose monomers. Cellulose provides structural support
and rigidity to plant cells.
Why Wrong: A - Starch is an energy storage molecule found in plant cells, not
the main structural component of cell walls. C - Glycogen is the animal storage
polysaccharide. D - Lactose is a disaccharide found in milk.
6. Why is it impossible for humans to digest cellulose?
A. Cellulose is too large to be digested
B. Humans lack the enzyme cellulase to break β-1,4-glycosidic bonds
C. Cellulose is not a carbohydrate
D. Cellulose is completely insoluble in water
Answer: B
Rationale: Humans cannot digest cellulose because they lack the enzyme
cellulase, which is required to break the β-1,4-glycosidic linkages in cellulose.
Herbivores have symbiotic microorganisms in their digestive systems that
Biological Molecules | 2026/2027 Academic
Year | Verified Exam Molecular Biology and
Biochemistry | Actual Q&A | Pre-Medical and
Life Sciences Students
Introduction
This comprehensive 65-question practice set covers the Molecular Biology
and Biochemistry curriculum focusing on Biological Molecules, including
Carbohydrates, Lipids, Proteins, Nucleic Acids, and key Laboratory
Techniques. The examination emphasizes the rigorous application of
biochemical principles, molecular structures, metabolic pathways, and the
systematic use of experimental methods to analyze biological
macromolecules. Learners are required to evaluate molecular structures,
metabolic functions, and the biochemical basis of life processes. Each item
includes a fully worked rationale, a distractor analysis clarifying why
incorrect options are wrong, and a reference to standard biochemistry and
molecular biology textbooks.
Domain 1: Carbohydrates & Glycobiology (Questions 1-13)
1. Dehydration synthesis leads to the formation of:
A. Monomers
B. Polymers
C. Water and polymers
D. None of the above
Answer: C
Rationale: Dehydration synthesis (also called condensation reaction) joins
monomers together to form polymers while releasing a molecule of water for
each bond formed. For example, monosaccharides join via glycosidic bonds to
form polysaccharides with the release of H₂O.
,Why Wrong: A - Dehydration synthesis consumes monomers to build polymers. B
- While polymers are formed, water is also produced, making C the complete
answer. D - Incorrect.
2. Which of the following is an example of a monosaccharide?
A. Fructose
B. Glucose
C. Galactose
D. All of the above
Answer: D
Rationale: Fructose, glucose, and galactose are all monosaccharides (simple
sugars) with the molecular formula C₆H₁₂O₆. Glucose and galactose are aldoses,
while fructose is a ketose.
Why Wrong: A, B, and C are each correct individually, but D is the most complete
answer as all three are monosaccharides.
3. Cellulose and starch are examples of:
A. Monosaccharides
B. Disaccharides
C. Lipids
D. Polysaccharides
Answer: D
Rationale: Both cellulose and starch are polysaccharides—complex
carbohydrates composed of many glucose monomers linked by glycosidic bonds.
Starch is the energy storage polysaccharide in plants, while cellulose is a
structural polysaccharide in plant cell walls.
Why Wrong: A - Monosaccharides are single sugar units. B - Disaccharides are
two sugar units linked together. C - Lipids are a different class of
macromolecules.
4. Lactose is a disaccharide formed by the formation of a ________ bond
between glucose and ________:
A. Glycosidic; lactose
, B. Glycosidic; galactose
C. Hydrogen; sucrose
D. Hydrogen; fructose
Answer: B
Rationale: Lactose (milk sugar) is a disaccharide consisting of glucose and
galactose linked by a β-1,4-glycosidic bond. The bond type is glycosidic, not
hydrogen, and the second monosaccharide is galactose.
Why Wrong: A - Lactose is the product, not the second monosaccharide. C -
Sucrose is glucose + fructose. D - Hydrogen bonds are not the primary linkage in
disaccharides.
5. Plant cell walls contain which of the following in abundance?
A. Starch
B. Cellulose
C. Glycogen
D. Lactose
Answer: B
Rationale: Plant cell walls are primarily composed of cellulose, a polysaccharide
made of β-1,4-linked glucose monomers. Cellulose provides structural support
and rigidity to plant cells.
Why Wrong: A - Starch is an energy storage molecule found in plant cells, not
the main structural component of cell walls. C - Glycogen is the animal storage
polysaccharide. D - Lactose is a disaccharide found in milk.
6. Why is it impossible for humans to digest cellulose?
A. Cellulose is too large to be digested
B. Humans lack the enzyme cellulase to break β-1,4-glycosidic bonds
C. Cellulose is not a carbohydrate
D. Cellulose is completely insoluble in water
Answer: B
Rationale: Humans cannot digest cellulose because they lack the enzyme
cellulase, which is required to break the β-1,4-glycosidic linkages in cellulose.
Herbivores have symbiotic microorganisms in their digestive systems that
