BIOD 121 CASE STUDY MODULE 3 QUESTIONS & SOLUTIONS
WITH VERIFIED CORRECT ANSWERS.
1. A patient presents with persistent fatigue and low hemoglobin levels.
Which physiological mechanism most likely explains the reduced
oxygen-carrying capacity?
A. Increased plasma volume
B. Decreased erythropoietin production
C. Increased leukocyte count
D. Enhanced platelet aggregation
Correct Answer: B
Explanation: Erythropoietin stimulates red blood cell production;
reduced levels lead to anemia and decreased oxygen transport. Other
options do not directly affect oxygen-carrying capacity.
2. In a case study of enzyme deficiency, a mutation alters the active site of
an enzyme. What is the most immediate effect?
A. Increased substrate concentration
B. Reduced enzyme specificity
C. Increased product formation
D. Enhanced enzyme stability
Correct Answer: B
Explanation: Changes in the active site affect substrate binding, reducing
specificity and enzyme function. The other options are not direct
consequences of active site alteration.
3. A bacterial infection shows resistance to multiple antibiotics. What is the
most likely mechanism?
A. Reduced metabolic rate
B. Horizontal gene transfer
C. Increased cell size
D. Decreased mutation rate
Correct Answer: B
Explanation: Horizontal gene transfer allows bacteria to acquire
resistance genes rapidly. Other options do not explain multi-drug
resistance effectively.
,4. A patient has high blood glucose but low insulin levels. Which condition
is most likely?
A. Type 2 diabetes mellitus
B. Type 1 diabetes mellitus
C. Hyperthyroidism
D. Hypoglycemia
Correct Answer: B
Explanation: Type 1 diabetes involves autoimmune destruction of insulin-
producing beta cells, leading to low insulin and high glucose.
5. Which cellular organelle is most directly responsible for ATP production
in aerobic respiration?
A. Nucleus
B. Ribosome
C. Mitochondrion
D. Golgi apparatus
Correct Answer: C
Explanation: Mitochondria generate ATP through oxidative
phosphorylation. Other organelles serve different cellular functions.
6. A case study shows impaired gas exchange in the lungs. Which structure
is primarily affected?
A. Bronchi
B. Alveoli
C. Trachea
D. Larynx
Correct Answer: B
Explanation: Alveoli are the primary sites of gas exchange. Damage here
directly impairs oxygen and carbon dioxide diffusion.
7. Which process explains the movement of water across a semipermeable
membrane?
A. Diffusion
B. Active transport
C. Osmosis
D. Facilitated diffusion
Correct Answer: C
, Explanation: Osmosis specifically refers to water movement across
membranes. Other processes involve solutes.
8. A mutation causes a premature stop codon in mRNA. What is the likely
outcome?
A. Longer protein
B. Nonfunctional truncated protein
C. Increased protein activity
D. No change in protein
Correct Answer: B
Explanation: A stop codon halts translation early, producing a shortened,
usually nonfunctional protein.
9. In a case of dehydration, what hormonal response is expected?
A. Decreased ADH secretion
B. Increased ADH secretion
C. Decreased aldosterone
D. Increased insulin
Correct Answer: B
Explanation: ADH increases water reabsorption to conserve body fluids
during dehydration.
10.Which phase of mitosis involves chromosome alignment at the equatorial
plate?
A. Prophase
B. Metaphase
C. Anaphase
D. Telophase
Correct Answer: B
Explanation: During metaphase, chromosomes align at the cell’s equator
before separation.
11.A patient has a deficiency in vitamin D. What is the most likely
physiological consequence?
A. Increased blood clotting
B. Weak bone mineralization
, C. Enhanced nerve conduction
D. Increased muscle mass
Correct Answer: B
Explanation: Vitamin D is essential for calcium absorption; deficiency
leads to weak bones.
12.Which macromolecule is primarily responsible for genetic information
storage?
A. Lipids
B. Proteins
C. Carbohydrates
D. Nucleic acids
Correct Answer: D
Explanation: DNA and RNA (nucleic acids) store and transmit genetic
information.
13.In a case of respiratory acidosis, what change occurs in blood pH?
A. Increases
B. Decreases
C. Remains constant
D. Becomes neutral
Correct Answer: B
Explanation: Accumulation of CO₂ lowers pH, causing acidosis.
14.Which immune cells are primarily responsible for antibody production?
A. T lymphocytes
B. B lymphocytes
C. Macrophages
D. Neutrophils
Correct Answer: B
Explanation: B cells differentiate into plasma cells that produce
antibodies.
15.A patient experiences muscle fatigue due to lactic acid buildup. What
pathway is involved?
A. Krebs cycle
WITH VERIFIED CORRECT ANSWERS.
1. A patient presents with persistent fatigue and low hemoglobin levels.
Which physiological mechanism most likely explains the reduced
oxygen-carrying capacity?
A. Increased plasma volume
B. Decreased erythropoietin production
C. Increased leukocyte count
D. Enhanced platelet aggregation
Correct Answer: B
Explanation: Erythropoietin stimulates red blood cell production;
reduced levels lead to anemia and decreased oxygen transport. Other
options do not directly affect oxygen-carrying capacity.
2. In a case study of enzyme deficiency, a mutation alters the active site of
an enzyme. What is the most immediate effect?
A. Increased substrate concentration
B. Reduced enzyme specificity
C. Increased product formation
D. Enhanced enzyme stability
Correct Answer: B
Explanation: Changes in the active site affect substrate binding, reducing
specificity and enzyme function. The other options are not direct
consequences of active site alteration.
3. A bacterial infection shows resistance to multiple antibiotics. What is the
most likely mechanism?
A. Reduced metabolic rate
B. Horizontal gene transfer
C. Increased cell size
D. Decreased mutation rate
Correct Answer: B
Explanation: Horizontal gene transfer allows bacteria to acquire
resistance genes rapidly. Other options do not explain multi-drug
resistance effectively.
,4. A patient has high blood glucose but low insulin levels. Which condition
is most likely?
A. Type 2 diabetes mellitus
B. Type 1 diabetes mellitus
C. Hyperthyroidism
D. Hypoglycemia
Correct Answer: B
Explanation: Type 1 diabetes involves autoimmune destruction of insulin-
producing beta cells, leading to low insulin and high glucose.
5. Which cellular organelle is most directly responsible for ATP production
in aerobic respiration?
A. Nucleus
B. Ribosome
C. Mitochondrion
D. Golgi apparatus
Correct Answer: C
Explanation: Mitochondria generate ATP through oxidative
phosphorylation. Other organelles serve different cellular functions.
6. A case study shows impaired gas exchange in the lungs. Which structure
is primarily affected?
A. Bronchi
B. Alveoli
C. Trachea
D. Larynx
Correct Answer: B
Explanation: Alveoli are the primary sites of gas exchange. Damage here
directly impairs oxygen and carbon dioxide diffusion.
7. Which process explains the movement of water across a semipermeable
membrane?
A. Diffusion
B. Active transport
C. Osmosis
D. Facilitated diffusion
Correct Answer: C
, Explanation: Osmosis specifically refers to water movement across
membranes. Other processes involve solutes.
8. A mutation causes a premature stop codon in mRNA. What is the likely
outcome?
A. Longer protein
B. Nonfunctional truncated protein
C. Increased protein activity
D. No change in protein
Correct Answer: B
Explanation: A stop codon halts translation early, producing a shortened,
usually nonfunctional protein.
9. In a case of dehydration, what hormonal response is expected?
A. Decreased ADH secretion
B. Increased ADH secretion
C. Decreased aldosterone
D. Increased insulin
Correct Answer: B
Explanation: ADH increases water reabsorption to conserve body fluids
during dehydration.
10.Which phase of mitosis involves chromosome alignment at the equatorial
plate?
A. Prophase
B. Metaphase
C. Anaphase
D. Telophase
Correct Answer: B
Explanation: During metaphase, chromosomes align at the cell’s equator
before separation.
11.A patient has a deficiency in vitamin D. What is the most likely
physiological consequence?
A. Increased blood clotting
B. Weak bone mineralization
, C. Enhanced nerve conduction
D. Increased muscle mass
Correct Answer: B
Explanation: Vitamin D is essential for calcium absorption; deficiency
leads to weak bones.
12.Which macromolecule is primarily responsible for genetic information
storage?
A. Lipids
B. Proteins
C. Carbohydrates
D. Nucleic acids
Correct Answer: D
Explanation: DNA and RNA (nucleic acids) store and transmit genetic
information.
13.In a case of respiratory acidosis, what change occurs in blood pH?
A. Increases
B. Decreases
C. Remains constant
D. Becomes neutral
Correct Answer: B
Explanation: Accumulation of CO₂ lowers pH, causing acidosis.
14.Which immune cells are primarily responsible for antibody production?
A. T lymphocytes
B. B lymphocytes
C. Macrophages
D. Neutrophils
Correct Answer: B
Explanation: B cells differentiate into plasma cells that produce
antibodies.
15.A patient experiences muscle fatigue due to lactic acid buildup. What
pathway is involved?
A. Krebs cycle
