1. Which component of the extracellular matrix provides tensile strength to many
connective tissues?
A. Collagen fibers
B. Glycogen granules
C. Actin filaments alone
D. Ribosomal RNA
Answer: A. Collagen fibers.
2. True or false: The refractory period of a neuron helps limit how frequently action
potentials can occur and supports one-way propagation along an axon.
Answer: True.
Explanation: During the absolute refractory period, voltage-gated sodium channels cannot
immediately reopen. This helps prevent an action potential from traveling backward along
the recently activated portion of the axon.
3. Which hormone stimulates the kidneys to increase red blood cell production
indirectly by acting on red bone marrow?
A. Erythropoietin
B. Calcitonin
C. Insulin
D. Prolactin
Answer: A. Erythropoietin.
4. A patient has inflammation of the meninges. Which structures are directly affected?
A. Membranes surrounding the brain and spinal cord
B. The inner lining of the stomach
C. The walls of the renal tubules
D. The cartilage covering the knee joint
Answer: A. Membranes surrounding the brain and spinal cord.
5. Which organelle contains enzymes that break down worn-out cell components and
certain ingested materials?
A. Lysosome
B. Nucleolus
C. Centriole
D. Smooth endoplasmic reticulum
Answer: A. Lysosome.
,6. Fill in the blank: The main protein responsible for the elastic recoil of lung tissue is
______.
Answer: Elastin.
7. Which valve prevents blood from flowing backward from the aorta into the left
ventricle during ventricular relaxation?
A. Tricuspid valve
B. Pulmonary valve
C. Aortic valve
D. Mitral valve
Answer: C. Aortic valve.
8. A person has a damaged Achilles tendon. Which movement is most likely to
become difficult or weak?
A. Plantar flexion of the foot
B. Flexion of the elbow
C. Abduction of the shoulder
D. Extension of the fingers
Answer: A. Plantar flexion of the foot.
Explanation: The Achilles tendon connects the calf muscles, especially the gastrocnemius
and soleus, to the calcaneus. It transmits force that helps raise the heel and point the foot
downward.
9. Which structure carries newly formed urine from a renal papilla into a minor calyx?
A. Collecting duct opening
B. Ureter
C. Renal artery
D. Proximal convoluted tubule
Answer: A. Collecting duct opening.
10. True or false: The cornea contributes significantly to the refraction of light
entering the eye.
Answer: True.
11. Which type of chemical bond joins amino acids together in a protein's primary
structure?
A. Peptide bond
B. Hydrogen bond only
C. Ionic bond between all amino acids
D. Phosphodiester bond
,Answer: A. Peptide bond.
12. Which cells in the stomach secrete pepsinogen, the inactive precursor of pepsin?
A. Chief cells
B. Parietal cells
C. Goblet cells
D. Beta cells
Answer: A. Chief cells.
13. A patient has reduced secretion of cortisol. Which response may be impaired
during prolonged physiological stress?
A. Regulation of metabolism and support of the stress response
B. Formation of visual images by the retina
C. Production of bile salts by the gallbladder
D. Mechanical filtration of air by nasal hairs alone
Answer: A. Regulation of metabolism and support of the stress response.
14. Which structure is the principal site of gas exchange in the placenta between
maternal and fetal circulations?
A. Chorionic villi
B. Amniotic cavity
C. Cervical canal
D. Ovarian follicles
Answer: A. Chorionic villi.
15. Which of the following is a major function of the sinoatrial node?
A. Initiating the normal electrical rhythm of the heart
B. Preventing all blood from entering the ventricles
C. Producing red blood cells
D. Filtering plasma in the kidneys
Answer: A. Initiating the normal electrical rhythm of the heart.
16. Match each structure with its correct description.
1. Osteon
2. Alveolus
3. Nephron
4. Villus
A. Functional unit of the kidney
B. Microscopic air sac for gas exchange
, C. Structural unit of compact bone
D. Small intestinal projection that increases absorptive surface area
Answer: 1–C, 2–B, 3–A, 4–D.
17. Which substance acts as the main immediate energy source for many cells under
normal conditions?
A. ATP
B. DNA
C. Collagen
D. Bile
Answer: A. ATP.
18. True or false: The adrenal cortex produces steroid hormones, including cortisol
and aldosterone.
Answer: True.
19. A patient has damage to the phrenic nerve. Which function is most directly
threatened?
A. Diaphragm contraction during breathing
B. Contraction of the urinary bladder only
C. Production of thyroid hormones
D. Detection of sound by cochlear hair cells
Answer: A. Diaphragm contraction during breathing.
Explanation: The phrenic nerves arise primarily from spinal nerves C3–C5 and provide the
main motor supply to the diaphragm.
20. Which type of blood cell is normally the most abundant formed element in human
blood?
A. Erythrocyte
B. Neutrophil
C. Lymphocyte
D. Platelet
Answer: A. Erythrocyte.
21. Which structure of the inner ear contains the sensory receptors responsible for
hearing?
A. Organ of Corti
B. Semicircular ducts only
C. Eustachian tube
D. Tympanic membrane