BIOS 255 Anatomy & Physiology III review Questions and Answers|Accurate|Verified 2026

BIOS 255 Anatomy & Physiology III review Questions
and Answers
Cardiovascular Physiology
1. Which chamber receives deoxygenated blood from systemic circulation?
A. Left Atrium
B. Right Atrium
C. Left Ventricle
D. Right Ventricle
Answer: B) Right Atrium
Rationale: Venous return enters the right atrium via superior/inferior vena cava.

2. The pacemaker of the heart is:
A. AV Node
B. SA Node
C. Purkinje Fibers
D. Bundle of His
Answer: B) SA Node
Rationale: SA node initiates depolarization.

3. Cardiac output is calculated as:
A. HR ÷ SV
B. HR × SV
C. SV ÷ HR
D. BP × HR
Answer: B) HR × SV
Rationale: Stroke volume multiplied by heart rate.

4. Which valve prevents backflow into the left atrium?
A. Tricuspid
B. Pulmonary
C. Mitral (Bicuspid)
D. Aortic
Answer: C) Mitral (Bicuspid)

5. Which factor increases afterload?
A. Vasodilation
B. Hypertension
C. Bradycardia
D. Hypovolemia
Answer: B) Hypertension

Blood & Hemostasis
6. Which protein is converted to fibrin during clot formation?
A. Hemoglobin
B. Albumin
C. Fibrinogen

,D. Prothrombin
Answer: C) Fibrinogen
7. Universal blood donor type:
A. AB
B. O
C. A
D. B
Answer: B) O

8. Which ion is essential for clotting cascade?
A. Sodium
B. Potassium
C. Calcium
D. Chloride
Answer: C) Calcium

9. Platelets originate from:
A. Monocytes
B. Megakaryocytes
C. Lymphocytes
D. Erythroblasts
Answer: B) Megakaryocytes

10. Hematocrit measures:
A. Plasma proteins
B. RBC percentage
C. WBC count
D. Platelet volume
Answer: B) RBC percentage

Immune System

11. MHC Class I presents antigens to:
A. Helper T cells
B. Cytotoxic T cells
C. B cells
D. NK cells
Answer: B) Cytotoxic T cells

12. MHC Class II presents antigens to:
A. Helper T cells
B. Cytotoxic T cells
C. NK cells
D. Macrophages
Answer: A) Helper T cells

13. Innate immunity includes:
A. Antibody production

, B. Memory cells
C. Skin barrier
D. T cell activation
Answer: C) Skin barrier

14. Adaptive immunity is characterized by:
A. Non‑specific response
B. Memory formation
C. Immediate defense
D. Physical barriers
Answer: B) Memory formation

15. Which cells produce antibodies?
A. T cells
B. Plasma cells (B cells)
C. NK cells
D. Macrophages
Answer: B) Plasma cells (B cells)

Respiratory Physiology

16. Primary muscle of inspiration:
A. Intercostals
B. Diaphragm
C. Sternocleidomastoid
D. Abdominals
Answer: B) Diaphragm

17. Gas exchange occurs in:
A. Bronchi
B. Bronchioles
C. Alveoli
D. Trachea
Answer: C) Alveoli

18. Normal resting respiratory rate in adults:
A. 6–10/min
B. 12–20/min
C. 20–30/min
D. 30–40/min
Answer: B) 12–20/min

19. Oxygen binds to hemoglobin at:
A. Iron atom in heme group
B. Globin chains
C. Plasma proteins
D. Platelets
Answer: A) Iron atom in heme group