BIOL 134 Exam 4 (Chapters 42–47, Week 16)
Questions and Answers
Question 1
Which of the following structures is primarily responsible for gas exchange in
mammals?
A. Trachea
• B. Alveoli
C. Bronchi
D. Diaphragm
Rationale: Alveoli are the microscopic sacs in the lungs where oxygen diffuses into
blood and carbon dioxide diffuses out. The trachea and bronchi are conduits, while the
diaphragm aids ventilation but not direct exchange.
Question 2
In vertebrate circulation, which chamber pumps oxygenated blood to the systemic
circuit?
A. Right atrium
B. Right ventricle
• C. Left ventricle
D. Left atrium
Rationale: The left ventricle has the thickest walls and pumps oxygen-rich blood through
the aorta to the entire body.
Question 3
Which hormone regulates water reabsorption in the kidney’s collecting ducts?
A. Insulin
B. Aldosterone
• C. Antidiuretic hormone (ADH)
D. Cortisol
Rationale: ADH increases aquaporin channels in the collecting ducts, allowing more
water reabsorption and concentrating urine.
Question 4
Which immune cells are the first responders to bacterial infection?
A. B cells
• B. Neutrophils
C. T helper cells
D. Natural killer cells
Rationale: Neutrophils are phagocytic cells that rapidly migrate to infection sites,
engulfing bacteria before adaptive immunity is activated.
Question 5
Which of the following is an example of innate immunity?
A. Antibody production
,B. Memory cell activation
• C. Skin barrier
D. Vaccination
Rationale: Innate immunity includes nonspecific defenses like skin, mucous
membranes, and phagocytes. Antibodies and memory cells are adaptive.
Question 6
Which reproductive strategy maximizes offspring survival in mammals?
A. External fertilization
B. Oviparity
• C. Viviparity with parental care
D. Broadcast spawning
Rationale: Mammals exhibit viviparity, where embryos develop internally, and parental
care ensures higher survival rates compared to external fertilization.
Question 7
Which of the following best describes homeostasis?
A. Maintaining constant external environment
• B. Maintaining stable internal conditions despite external changes
C. Rapid adaptation to new environments
D. Genetic regulation of traits
Rationale: Homeostasis is the regulation of internal conditions (temperature, pH,
glucose) to remain within narrow limits despite external fluctuations.
Question 8
Which structure in the nephron is primarily responsible for filtration?
A. Loop of Henle
• B. Glomerulus
C. Collecting duct
D. Distal tubule
Rationale: The glomerulus filters blood plasma into the nephron, initiating urine
formation.
Question 9
Which immune cell type directly destroys virus-infected cells?
A. B cells
• B. Cytotoxic T cells
C. Helper T cells
D. Macrophages
Rationale: Cytotoxic T cells recognize infected cells via MHC I and induce apoptosis.
Question 10
Which hormone stimulates milk production in mammals?
A. Oxytocin
• B. Prolactin
C. Estrogen
, D. Progesterone
Rationale: Prolactin promotes milk synthesis; oxytocin triggers milk ejection.
Question 11
Which circulatory system feature is unique to fish compared to mammals?
A. Double circulation
• B. Single circulation
C. Pulmonary circuit
D. Four-chambered heart
Rationale: Fish have a two-chambered heart and single circuit: heart → gills → body →
heart.
Question 12
Which of the following is an adaptive immune response?
A. Inflammation
• B. Antibody production
C. Fever
D. Skin barrier
Rationale: Antibody production is specific and adaptive, unlike nonspecific innate
defenses.
Question 13
Which part of the nephron establishes the osmotic gradient for water reabsorption?
A. Proximal tubule
• B. Loop of Henle
C. Distal tubule
D. Collecting duct
Rationale: The loop of Henle creates a concentration gradient in the medulla, enabling
water reabsorption.
Question 14
Which endocrine gland regulates metabolism through thyroxine secretion?
A. Pituitary
• B. Thyroid
C. Adrenal
D. Pancreas
Rationale: The thyroid gland secretes thyroxine (T4), which controls metabolic rate.
Question 15
Which reproductive structure produces sperm in mammals?
A. Epididymis
• B. Seminiferous tubules
C. Vas deferens
D. Prostate gland
Rationale: Seminiferous tubules in the testes are the site of spermatogenesis.
Questions and Answers
Question 1
Which of the following structures is primarily responsible for gas exchange in
mammals?
A. Trachea
• B. Alveoli
C. Bronchi
D. Diaphragm
Rationale: Alveoli are the microscopic sacs in the lungs where oxygen diffuses into
blood and carbon dioxide diffuses out. The trachea and bronchi are conduits, while the
diaphragm aids ventilation but not direct exchange.
Question 2
In vertebrate circulation, which chamber pumps oxygenated blood to the systemic
circuit?
A. Right atrium
B. Right ventricle
• C. Left ventricle
D. Left atrium
Rationale: The left ventricle has the thickest walls and pumps oxygen-rich blood through
the aorta to the entire body.
Question 3
Which hormone regulates water reabsorption in the kidney’s collecting ducts?
A. Insulin
B. Aldosterone
• C. Antidiuretic hormone (ADH)
D. Cortisol
Rationale: ADH increases aquaporin channels in the collecting ducts, allowing more
water reabsorption and concentrating urine.
Question 4
Which immune cells are the first responders to bacterial infection?
A. B cells
• B. Neutrophils
C. T helper cells
D. Natural killer cells
Rationale: Neutrophils are phagocytic cells that rapidly migrate to infection sites,
engulfing bacteria before adaptive immunity is activated.
Question 5
Which of the following is an example of innate immunity?
A. Antibody production
,B. Memory cell activation
• C. Skin barrier
D. Vaccination
Rationale: Innate immunity includes nonspecific defenses like skin, mucous
membranes, and phagocytes. Antibodies and memory cells are adaptive.
Question 6
Which reproductive strategy maximizes offspring survival in mammals?
A. External fertilization
B. Oviparity
• C. Viviparity with parental care
D. Broadcast spawning
Rationale: Mammals exhibit viviparity, where embryos develop internally, and parental
care ensures higher survival rates compared to external fertilization.
Question 7
Which of the following best describes homeostasis?
A. Maintaining constant external environment
• B. Maintaining stable internal conditions despite external changes
C. Rapid adaptation to new environments
D. Genetic regulation of traits
Rationale: Homeostasis is the regulation of internal conditions (temperature, pH,
glucose) to remain within narrow limits despite external fluctuations.
Question 8
Which structure in the nephron is primarily responsible for filtration?
A. Loop of Henle
• B. Glomerulus
C. Collecting duct
D. Distal tubule
Rationale: The glomerulus filters blood plasma into the nephron, initiating urine
formation.
Question 9
Which immune cell type directly destroys virus-infected cells?
A. B cells
• B. Cytotoxic T cells
C. Helper T cells
D. Macrophages
Rationale: Cytotoxic T cells recognize infected cells via MHC I and induce apoptosis.
Question 10
Which hormone stimulates milk production in mammals?
A. Oxytocin
• B. Prolactin
C. Estrogen
, D. Progesterone
Rationale: Prolactin promotes milk synthesis; oxytocin triggers milk ejection.
Question 11
Which circulatory system feature is unique to fish compared to mammals?
A. Double circulation
• B. Single circulation
C. Pulmonary circuit
D. Four-chambered heart
Rationale: Fish have a two-chambered heart and single circuit: heart → gills → body →
heart.
Question 12
Which of the following is an adaptive immune response?
A. Inflammation
• B. Antibody production
C. Fever
D. Skin barrier
Rationale: Antibody production is specific and adaptive, unlike nonspecific innate
defenses.
Question 13
Which part of the nephron establishes the osmotic gradient for water reabsorption?
A. Proximal tubule
• B. Loop of Henle
C. Distal tubule
D. Collecting duct
Rationale: The loop of Henle creates a concentration gradient in the medulla, enabling
water reabsorption.
Question 14
Which endocrine gland regulates metabolism through thyroxine secretion?
A. Pituitary
• B. Thyroid
C. Adrenal
D. Pancreas
Rationale: The thyroid gland secretes thyroxine (T4), which controls metabolic rate.
Question 15
Which reproductive structure produces sperm in mammals?
A. Epididymis
• B. Seminiferous tubules
C. Vas deferens
D. Prostate gland
Rationale: Seminiferous tubules in the testes are the site of spermatogenesis.
