NEET Body Fluids and Circulation PYQs & Practice Questions

10 free NEET Biology questions on Body Fluids and Circulation, starting with previous year questions (2016–2026). Tap “Show answer” to check each one. No login needed.

Topics: Antibody Production · Enucleate Blood Cells · Phagocytic White Blood Cells · Symptoms of Dengue Fever · Cardiac Cycle - Stroke Volume Equality · Autonomic Regulation of Heart Rate · Factors Required for Blood Coagulation · Cardiac Conduction System · ABO Blood Grouping System · Calculating Cardiac Output · ECG - Wave Interpretation · Regulation of Cardiac Activity

1. Q1NEET 2026Sino-Atrial Node and Heart Rate

   The number of action potentials generated by sino-arterial node (SAN) in a healthy human is ______ per minute.

   • A. 70 - 75
   • B. 100 - 110
   • C. 120 - 140
   • D. 28 - 30
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   Answer: —

   The sino-atrial node (SAN), the natural pacemaker of the heart, generates action potentials at a rate of approximately 70-75 per minute in a healthy resting human, setting the normal resting heart rate.

2. Q2NEET 2026Heart Valves

   The opening between the right atrium and the right ventricle is guarded by_________

   • A. tricuspid valve
   • B. semilunar valve
   • C. sino-atrial node
   • D. bicuspid valve
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   Answer: —

   The opening between the right atrium and right ventricle is guarded by the tricuspid valve (three cusps). The bicuspid (mitral) valve guards the opening between the left atrium and left ventricle.

3. Q3NEET 2026Calculating eosinophils and lymphocytes count

   The WBC count of a person's blood sample is 8000/cu.mm. How many eosinophils and lymphocytes would be in the same blood sample approximately?

   • A. 300-500/cu.mm and 500-700/cu.mm, respectively
   • B. 300-500/cu.mm and 1200-1500/cu.mm, respectively
   • C. 100-120/cu.mm and 160-200/cu.mm, respectively
   • D. 160-240/cu.mm and 1600-2000/cu.mm, respectively
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   Answer: C — 100-120/cu.mm and 160-200/cu.mm, respectively

   Eosinophils are ~2-3% of total WBC (≈160-240/cu.mm) and lymphocytes are ~20-25% (≈1600-2000/cu.mm) of 8000/cu.mm.

4. Q4NEET 2025Regulation of Cardiac Activity

   Cardiac activities of the heart are regulated by : A. Nodal tissue, B. A special neural centre in the medulla oblongata, C. Adrenal medullary hormones, D. Adrenal cortical hormones. Choose the correct answer from the options given below :

   • A. A, B and C Only
   • B. A, B, C and D
   • C. A, C and D Only
   • D. A, B and D Only
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   Answer: —

   The heart is myogenic, auto-regulated by the nodal tissue (A). A special neural centre in the medulla oblongata moderates cardiac function via the autonomic nervous system (B). Adrenal medullary hormones (adrenaline) also increase cardiac output (C). Adrenal cortical hormones are not involved in direct cardiac regulation (D is false). So A, B and C only.

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5. Q5NEET 2024Cardiac Conduction System

   Following are the stages of pathway of conduction of an action potential through the heart: A. AV bundle B. Purkinje fibres C. AV node D. Bundle Branches E. SA node Choose the correct sequence of pathway from the options given below:

   • A. B-D-E-C-A
   • B. E-A-D-B-C
   • C. E-C-A-D-B
   • D. A-E-C-B-D
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   Answer: B — E-A-D-B-C

   The cardiac action potential pathway is: SA node (E) initiates the impulse → AV node (C) → AV bundle (A) → Bundle Branches (D) → Purkinje fibres (B), which spread the impulse through the ventricles. So the correct sequence is E-C-A-D-B.

6. Q6NEET 2024ECG - Wave Interpretation

   Match List I with List II: List I: (A) P wave (B) QRS complex (C) T wave (D) T-P gap List II: (I) Heart muscles are electrically silent. (II) Depolarisation of ventricles. (III) Depolarisation of atria. (IV) Repolarisation of ventricles. Choose the correct answer from the options given below:

   • A. A-II, B-III, C-I, D-IV
   • B. A-IV, B-II, C-I, D-III
   • C. A-I, B-III, C-IV, D-II
   • D. A-III, B-II, C-IV, D-I
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   Answer: C — A-I, B-III, C-IV, D-II

   P wave represents depolarisation of the atria (A-III). QRS complex represents depolarisation of the ventricles (B-II). T wave represents repolarisation of the ventricles (C-IV). T-P gap is when the heart muscles are electrically silent (D-I). So A-III, B-II, C-IV, D-I is correct.

7. Q7NEET 2023Electrocardiogram (ECG) Waves

   Match List I with List II: A. P-wave, B. Q-wave, C. QRS complex, D. T-wave. List II: I. Beginning of systole, II. Repolarisation of ventricles, III. Depolarisation of atria, IV. Depolarisation of ventricles. Choose the correct answer from the options given below.

   • A. A-IV, B-III, C-II, D-I
   • B. A-II, B-IV, C-I, D-III
   • C. A-III, B-I, C-IV, D-II
   • D. A-III, B-I, C-IV, D-II
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   Answer: B — A-II, B-IV, C-I, D-III

   P-wave represents depolarisation of the atria (A-III). Q-wave marks the beginning of systole (B-I). QRS complex represents depolarisation of the ventricles (C-IV). T-wave represents repolarisation of the ventricles (D-II). So the correct match is A-III, B-I, C-IV, D-II.

8. Q8NEET 2023Basophils - Structure and Function

   Which of the following statements are correct? A. Basophils are most abundant cells of the total WBCs. B. Basophils secrete histamine, serotonin and heparin. C. Basophils are involved in inflammatory response. D. Basophils have kidney shaped nucleus. E. Basophils are agranulocytes. Choose the correct answer from the options given below.

   • A. C and E only
   • B. B and C only
   • C. A and B only
   • D. D and E only
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   Answer: A — C and E only

   Statement B is correct — basophils secrete histamine, serotonin, and heparin. Statement C is correct — basophils play a role in the inflammatory response. Statement A is incorrect — neutrophils (not basophils) are the most abundant WBCs. Statement D is incorrect — monocytes (not basophils) have a kidney-shaped nucleus. Statement E is incorrect — basophils are granulocytes, not agranulocytes.

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9. Q9NEET 2022Oxygen Delivery to Tissues

   Under normal physiological conditions in human being every 100ml of oxygenated blood can deliver _____ ml of O₂ to the tissues.

   • A. 5 ml
   • B. 4 ml
   • C. 10 ml
   • D. 2 ml
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   Answer: —

   Under normal physiological conditions, every 100 ml of oxygenated blood delivers around 5 ml of O₂ to the tissues.

10. Q10NEET 2022Oxygen Delivery by Blood

    Under normal physiological conditions in human being every 100 ml of oxygenated blood can deliver ________ ml of O2 to the tissues.

    • A. 2 ml
    • B. 5 ml
    • C. 4 ml
    • D. 10 ml
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    Answer: A — 2 ml

    Under normal physiological conditions, 100 ml of oxygenated blood delivers approximately 5 ml of O2 to the tissues.