BIOL 271 Module 6 Practice Exam with correct
answers and detailed rationales graded A+
Section 1: Cell Biology and Membrane Transport
1. What is the basic structural and functional unit of the human body?
A. Tissue
B. Organ
C. Cell
D. Organ system
Rationale: Cells are the smallest living units capable of carrying out the essential processes of life.
2. Which organelle produces most cellular ATP?
A. Golgi apparatus
B. Lysosome
C. Mitochondrion
D. Ribosome
Rationale: Mitochondria generate most ATP through aerobic cellular respiration and oxidative
phosphorylation.
3. Which organelle synthesizes proteins?
A. Lysosome
B. Ribosome
C. Centriole
D. Peroxisome
Rationale: Ribosomes translate messenger RNA into polypeptide chains.
4. What is the primary function of the plasma membrane?
A. Store genetic information
B. Produce ribosomes
C. Regulate movement of substances into and out of the cell
D. Manufacture all cellular ATP
Rationale: The selectively permeable plasma membrane controls exchange between the intracellular
and extracellular environments.
5. Which process moves molecules from high to low concentration without requiring cellular
energy?
A. Active transport
B. Passive transport
C. Endocytosis
D. Exocytosis
,Rationale: Passive transport follows a concentration or electrochemical gradient and does not
directly require ATP.
6. What is osmosis?
A. Movement of proteins using ATP
B. Net movement of water across a selectively permeable membrane
C. Movement of solutes against their gradients
D. Breakdown of glucose
Rationale: Osmosis is the net movement of water across a membrane in response to differences in
effective solute concentration.
7. Which transport process requires ATP directly?
A. Simple diffusion
B. Osmosis
C. Facilitated diffusion
D. Primary active transport
Rationale: Primary active transport uses energy, commonly from ATP hydrolysis, to move substances
against their electrochemical gradients.
8. What happens to an animal cell placed in a strongly hypotonic solution?
A. It loses water and shrinks
B. It gains water and may lyse
C. It remains unchanged in every case
D. It immediately stops all metabolism
Rationale: A hypotonic environment promotes water entry into the cell, potentially causing swelling
and rupture.
9. Which organelle modifies, sorts, and packages proteins?
A. Nucleus
B. Mitochondrion
C. Golgi apparatus
D. Smooth endoplasmic reticulum
Rationale: The Golgi apparatus processes and directs proteins and lipids to their appropriate
destinations.
10. Which structure contains most of a human cell's DNA?
A. Golgi apparatus
B. Lysosome
C. Nucleus
D. Cell membrane
Rationale: The nucleus houses the chromosomes containing most of the cell's genetic information.
11. What is the main function of lysosomes?
,A. Protein translation
B. Intracellular digestion and recycling
C. ATP production
D. DNA replication
Rationale: Lysosomes contain hydrolytic enzymes that break down cellular waste, macromolecules,
and damaged components.
12. Which structure is primarily responsible for synthesizing lipids and helping detoxify certain
substances?
A. Rough endoplasmic reticulum
B. Smooth endoplasmic reticulum
C. Nucleolus
D. Ribosome
Rationale: Smooth endoplasmic reticulum synthesizes lipids and participates in detoxification and
calcium storage.
13. What is the principal component of a typical biological membrane?
A. Cellulose
B. Phospholipid bilayer
C. Triglyceride layer
D. DNA bilayer
Rationale: Amphipathic phospholipids form a bilayer with hydrophilic heads facing aqueous
environments and hydrophobic tails facing inward.
14. Which type of solution has approximately the same effective osmotic concentration as a cell?
A. Hypertonic
B. Isotonic
C. Hypotonic
D. Saturated
Rationale: An isotonic solution causes no sustained net water movement that changes cell volume.
15. What is facilitated diffusion?
A. ATP-dependent movement through a pump
B. Passive movement through membrane proteins
C. Vesicle formation around extracellular material
D. Movement of water only
Rationale: Channel or carrier proteins allow substances to move down their electrochemical
gradients without direct ATP expenditure.
16. Which cellular process engulfs large particles?
A. Exocytosis
B. Osmosis
C. Phagocytosis
D. Simple diffusion
, Rationale: Phagocytosis is a type of endocytosis in which a cell surrounds and internalizes large
particles.
17. What occurs during exocytosis?
A. A cell takes in water only
B. DNA is replicated
C. A vesicle fuses with the plasma membrane and releases its contents
D. A ribosome makes a protein
Rationale: Exocytosis exports substances when intracellular vesicles fuse with the cell membrane.
18. Which organelle contains enzymes that help break down hydrogen peroxide?
A. Nucleolus
B. Ribosome
C. Peroxisome
D. Centrosome
Rationale: Peroxisomes contain enzymes, including catalase, that detoxify hydrogen peroxide and
participate in lipid metabolism.
19. Which component forms the main framework of the cell's internal support system?
A. Chromatin
B. Glycogen
C. Cytoskeleton
D. Nucleoplasm
Rationale: Microfilaments, intermediate filaments, and microtubules help maintain cell shape and
support movement and intracellular transport.
20. What is the primary function of the nucleolus?
A. Produce ATP
B. Assemble ribosomal subunits
C. Digest bacteria
D. Transport oxygen
Rationale: The nucleolus produces ribosomal RNA and assembles components of ribosomes.
Section 2: Genetics and Cell Division
21. What is DNA's primary role?
A. Directly transport oxygen
B. Store hereditary information
C. Digest cellular waste
D. Form the plasma membrane
Rationale: DNA stores genetic instructions used in cellular function, growth, and reproduction.
22. Which nitrogenous base pairs with adenine in DNA?
answers and detailed rationales graded A+
Section 1: Cell Biology and Membrane Transport
1. What is the basic structural and functional unit of the human body?
A. Tissue
B. Organ
C. Cell
D. Organ system
Rationale: Cells are the smallest living units capable of carrying out the essential processes of life.
2. Which organelle produces most cellular ATP?
A. Golgi apparatus
B. Lysosome
C. Mitochondrion
D. Ribosome
Rationale: Mitochondria generate most ATP through aerobic cellular respiration and oxidative
phosphorylation.
3. Which organelle synthesizes proteins?
A. Lysosome
B. Ribosome
C. Centriole
D. Peroxisome
Rationale: Ribosomes translate messenger RNA into polypeptide chains.
4. What is the primary function of the plasma membrane?
A. Store genetic information
B. Produce ribosomes
C. Regulate movement of substances into and out of the cell
D. Manufacture all cellular ATP
Rationale: The selectively permeable plasma membrane controls exchange between the intracellular
and extracellular environments.
5. Which process moves molecules from high to low concentration without requiring cellular
energy?
A. Active transport
B. Passive transport
C. Endocytosis
D. Exocytosis
,Rationale: Passive transport follows a concentration or electrochemical gradient and does not
directly require ATP.
6. What is osmosis?
A. Movement of proteins using ATP
B. Net movement of water across a selectively permeable membrane
C. Movement of solutes against their gradients
D. Breakdown of glucose
Rationale: Osmosis is the net movement of water across a membrane in response to differences in
effective solute concentration.
7. Which transport process requires ATP directly?
A. Simple diffusion
B. Osmosis
C. Facilitated diffusion
D. Primary active transport
Rationale: Primary active transport uses energy, commonly from ATP hydrolysis, to move substances
against their electrochemical gradients.
8. What happens to an animal cell placed in a strongly hypotonic solution?
A. It loses water and shrinks
B. It gains water and may lyse
C. It remains unchanged in every case
D. It immediately stops all metabolism
Rationale: A hypotonic environment promotes water entry into the cell, potentially causing swelling
and rupture.
9. Which organelle modifies, sorts, and packages proteins?
A. Nucleus
B. Mitochondrion
C. Golgi apparatus
D. Smooth endoplasmic reticulum
Rationale: The Golgi apparatus processes and directs proteins and lipids to their appropriate
destinations.
10. Which structure contains most of a human cell's DNA?
A. Golgi apparatus
B. Lysosome
C. Nucleus
D. Cell membrane
Rationale: The nucleus houses the chromosomes containing most of the cell's genetic information.
11. What is the main function of lysosomes?
,A. Protein translation
B. Intracellular digestion and recycling
C. ATP production
D. DNA replication
Rationale: Lysosomes contain hydrolytic enzymes that break down cellular waste, macromolecules,
and damaged components.
12. Which structure is primarily responsible for synthesizing lipids and helping detoxify certain
substances?
A. Rough endoplasmic reticulum
B. Smooth endoplasmic reticulum
C. Nucleolus
D. Ribosome
Rationale: Smooth endoplasmic reticulum synthesizes lipids and participates in detoxification and
calcium storage.
13. What is the principal component of a typical biological membrane?
A. Cellulose
B. Phospholipid bilayer
C. Triglyceride layer
D. DNA bilayer
Rationale: Amphipathic phospholipids form a bilayer with hydrophilic heads facing aqueous
environments and hydrophobic tails facing inward.
14. Which type of solution has approximately the same effective osmotic concentration as a cell?
A. Hypertonic
B. Isotonic
C. Hypotonic
D. Saturated
Rationale: An isotonic solution causes no sustained net water movement that changes cell volume.
15. What is facilitated diffusion?
A. ATP-dependent movement through a pump
B. Passive movement through membrane proteins
C. Vesicle formation around extracellular material
D. Movement of water only
Rationale: Channel or carrier proteins allow substances to move down their electrochemical
gradients without direct ATP expenditure.
16. Which cellular process engulfs large particles?
A. Exocytosis
B. Osmosis
C. Phagocytosis
D. Simple diffusion
, Rationale: Phagocytosis is a type of endocytosis in which a cell surrounds and internalizes large
particles.
17. What occurs during exocytosis?
A. A cell takes in water only
B. DNA is replicated
C. A vesicle fuses with the plasma membrane and releases its contents
D. A ribosome makes a protein
Rationale: Exocytosis exports substances when intracellular vesicles fuse with the cell membrane.
18. Which organelle contains enzymes that help break down hydrogen peroxide?
A. Nucleolus
B. Ribosome
C. Peroxisome
D. Centrosome
Rationale: Peroxisomes contain enzymes, including catalase, that detoxify hydrogen peroxide and
participate in lipid metabolism.
19. Which component forms the main framework of the cell's internal support system?
A. Chromatin
B. Glycogen
C. Cytoskeleton
D. Nucleoplasm
Rationale: Microfilaments, intermediate filaments, and microtubules help maintain cell shape and
support movement and intracellular transport.
20. What is the primary function of the nucleolus?
A. Produce ATP
B. Assemble ribosomal subunits
C. Digest bacteria
D. Transport oxygen
Rationale: The nucleolus produces ribosomal RNA and assembles components of ribosomes.
Section 2: Genetics and Cell Division
21. What is DNA's primary role?
A. Directly transport oxygen
B. Store hereditary information
C. Digest cellular waste
D. Form the plasma membrane
Rationale: DNA stores genetic instructions used in cellular function, growth, and reproduction.
22. Which nitrogenous base pairs with adenine in DNA?
