1. Cell Structure & Function
1. Which organelle is the primary site of ATP
production?
A. Nucleus
B. Ribosome
C. Mitochondrion
D. Golgi apparatus
Answer: C
Rationale: Mitochondria generate ATP via oxidative
phosphorylation. The nucleus stores DNA (A),
ribosomes synthesize proteins (B), and the Golgi
modifies and sorts proteins (D).
2. The fluid mosaic model describes the plasma
membrane as:
A. A rigid layer of polysaccharides
B. A static bilayer of phospholipids
C. A dynamic phospholipid bilayer with embedded
proteins
D. Protein sheets bound to glycolipids
Answer: C
Rationale: The fluid mosaic model envisions lipids
moving laterally with proteins interspersed. It is
neither rigid (A) nor static (B), nor composed of
sheets (D).
3. Which structure is unique to prokaryotic cells?
A. Endoplasmic reticulum
, B. Circular DNA chromosome
C. Mitochondria
D. Lysosomes
Answer: B
Rationale: Prokaryotes have a single circular
chromosome. ER (A), mitochondria (C), and
lysosomes (D) are membrane-bound organelles found
in eukaryotes.
4. Ribosomes function in:
A. DNA replication
B. Protein synthesis
C. Lipid degradation
D. Photosynthesis
Answer: B
Rationale: Ribosomes translate mRNA into
polypeptides. They do not replicate DNA (A), degrade
lipids (C), or carry out photosynthesis (D).
5. Which cytoskeletal element is made of tubulin and
involved in vesicle transport?
A. Actin filaments
B. Intermediate filaments
C. Microtubules
D. Cellulose microfibrils
Answer: C
Rationale: Microtubules, composed of α- and β-
tubulin, form tracks for motor proteins. Actin (A)
supports muscle contraction, intermediate filaments
, (B) provide tensile strength, and cellulose (D) is in
plant cell walls.
6. The Golgi apparatus is responsible for:
A. DNA packaging
B. Protein modification and sorting
C. Energy production
D. Protein synthesis
Answer: B
Rationale: Golgi cisternae add sugars and direct
proteins. DNA packaging (A) occurs in the nucleus,
energy production (C) in mitochondria, and protein
synthesis (D) at ribosomes.
7. Endocytosis and exocytosis both require:
A. ATP and membrane fusion
B. Ribosomes and mRNA
C. Simple diffusion
D. Osmosis
Answer: A
Rationale: Both are active processes needing energy
and vesicle–membrane fusion. They don’t involve
ribosomes (B), simple diffusion (C), or osmosis (D).
8. Which component contributes most to the
selective permeability of a cell membrane?
A. Carbohydrate chains
B. Integral proteins
C. Phospholipid bilayer
D. Cholesterol alone
Answer: C
1. Which organelle is the primary site of ATP
production?
A. Nucleus
B. Ribosome
C. Mitochondrion
D. Golgi apparatus
Answer: C
Rationale: Mitochondria generate ATP via oxidative
phosphorylation. The nucleus stores DNA (A),
ribosomes synthesize proteins (B), and the Golgi
modifies and sorts proteins (D).
2. The fluid mosaic model describes the plasma
membrane as:
A. A rigid layer of polysaccharides
B. A static bilayer of phospholipids
C. A dynamic phospholipid bilayer with embedded
proteins
D. Protein sheets bound to glycolipids
Answer: C
Rationale: The fluid mosaic model envisions lipids
moving laterally with proteins interspersed. It is
neither rigid (A) nor static (B), nor composed of
sheets (D).
3. Which structure is unique to prokaryotic cells?
A. Endoplasmic reticulum
, B. Circular DNA chromosome
C. Mitochondria
D. Lysosomes
Answer: B
Rationale: Prokaryotes have a single circular
chromosome. ER (A), mitochondria (C), and
lysosomes (D) are membrane-bound organelles found
in eukaryotes.
4. Ribosomes function in:
A. DNA replication
B. Protein synthesis
C. Lipid degradation
D. Photosynthesis
Answer: B
Rationale: Ribosomes translate mRNA into
polypeptides. They do not replicate DNA (A), degrade
lipids (C), or carry out photosynthesis (D).
5. Which cytoskeletal element is made of tubulin and
involved in vesicle transport?
A. Actin filaments
B. Intermediate filaments
C. Microtubules
D. Cellulose microfibrils
Answer: C
Rationale: Microtubules, composed of α- and β-
tubulin, form tracks for motor proteins. Actin (A)
supports muscle contraction, intermediate filaments
, (B) provide tensile strength, and cellulose (D) is in
plant cell walls.
6. The Golgi apparatus is responsible for:
A. DNA packaging
B. Protein modification and sorting
C. Energy production
D. Protein synthesis
Answer: B
Rationale: Golgi cisternae add sugars and direct
proteins. DNA packaging (A) occurs in the nucleus,
energy production (C) in mitochondria, and protein
synthesis (D) at ribosomes.
7. Endocytosis and exocytosis both require:
A. ATP and membrane fusion
B. Ribosomes and mRNA
C. Simple diffusion
D. Osmosis
Answer: A
Rationale: Both are active processes needing energy
and vesicle–membrane fusion. They don’t involve
ribosomes (B), simple diffusion (C), or osmosis (D).
8. Which component contributes most to the
selective permeability of a cell membrane?
A. Carbohydrate chains
B. Integral proteins
C. Phospholipid bilayer
D. Cholesterol alone
Answer: C
