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Body fluids and circulation: NEET MCQs with answers

155 questions on this topic of Human Physiology (NEET 2027 syllabus). Here are 12; tap one to see its answer and explanation.

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easy

1. A person's stroke volume is 75 mL and heart rate is 66 beats per minute. The cardiac output is:

  1. 4950 L/min
  2. 9.9 L/min
  3. 1.14 L/min
  4. 4.95 L/min
Show answer and explanation

Answer: (D) 4.95 L/min

Cardiac output = stroke volume × heart rate = 75 × 66 = 4950 mL/min = 4.95 L/min.

medium

2. The duration of one cardiac cycle in a normal human is about:

  1. 1.8 seconds
  2. 0.8 seconds
  3. 8 seconds
  4. 0.08 seconds
Show answer and explanation

Answer: (B) 0.8 seconds

With about 72 beats per minute, each cardiac cycle takes about 0.8 seconds. Each ventricle pumps about 70 mL per beat (stroke volume).

NCERT Class 11

hard

3. In fishes, the heart pumps out deoxygenated blood, which is oxygenated by the gills and supplied to the body parts, from where deoxygenated blood returns to the heart. This is called:

  1. Portal circulation
  2. Double circulation
  3. Incomplete double circulation
  4. Single circulation
Show answer and explanation

Answer: (D) Single circulation

Blood passes through the fish heart only once per circuit, so fishes have single circulation.

medium

4. Lymphocytes constitute about what percentage of total WBCs?

  1. 20–25 per cent
  2. 60–65 per cent
  3. 6–8 per cent
  4. 2–3 per cent
Show answer and explanation

Answer: (A) 20–25 per cent

Lymphocytes form 20–25 per cent of WBCs; they are of two major types, B and T, responsible for immune responses.

easy

5. A person's stroke volume is 60 mL and heart rate is 84 beats per minute. The cardiac output is:

  1. 5.04 L/min
  2. 10.1 L/min
  3. 0.714 L/min
  4. 5040 L/min
Show answer and explanation

Answer: (A) 5.04 L/min

Cardiac output = stroke volume × heart rate = 60 × 84 = 5040 mL/min = 5.04 L/min.

hard

6. Assertion (A): An Rh-negative person receiving Rh-positive blood for the first time may not show an immediate reaction. Reason (R): Antibodies against the Rh antigen are formed only after exposure to Rh-positive blood. Choose the correct option.

  1. Both A and R are true and R is the correct explanation of A
  2. Both A and R are true but R is not the correct explanation of A
  3. A is true but R is false
  4. A is false but R is true
Show answer and explanation

Answer: (A) Both A and R are true and R is the correct explanation of A

Rh-negative persons do not naturally have anti-Rh antibodies; they form them after exposure, so problems arise on subsequent exposure (as in erythroblastosis foetalis).

easy

7. A person's stroke volume is 65 mL and heart rate is 90 beats per minute. The cardiac output is:

  1. 11.7 L/min
  2. 5850 L/min
  3. 5.85 L/min
  4. 0.722 L/min
Show answer and explanation

Answer: (C) 5.85 L/min

Cardiac output = stroke volume × heart rate = 65 × 90 = 5850 mL/min = 5.85 L/min.

easy

8. If a healthy individual has a stroke volume of 75 mL and a heart rate of 90 beats/min, determine the total Cardiac Output:

  1. 16.5 L/min
  2. 6.75 L/min
  3. 67.5 L/min
  4. 5 L/min
Show answer and explanation

Answer: (B) 6.75 L/min

Cardiac Output = Heart Rate (HR) × Stroke Volume (SV) = 90 × 75 mL/min = 6750 mL/min = 6.75 L/min.

Quick tip: Cardiac output is normally around 5 Liters per minute for a healthy adult.

medium

9. The average life span of human RBCs, after which they are destroyed in the spleen, is about:

  1. 12 hours
  2. 1 year
  3. 120 days
  4. 12 days
Show answer and explanation

Answer: (C) 120 days

RBCs (5-5.5 million per mm3) are formed in red bone marrow in adults and live about 120 days. They are destroyed in the spleen, the graveyard of RBCs.

NCERT Class 11

medium

10. Proteins constitute what percentage of plasma?

  1. 1–2 per cent
  2. 90–92 per cent
  3. 45 per cent
  4. 6–8 per cent
Show answer and explanation

Answer: (D) 6–8 per cent

Plasma is 90–92 per cent water and 6–8 per cent proteins such as fibrinogen, globulins and albumins.

easy

11. If a healthy individual has a stroke volume of 80 mL and a heart rate of 65 beats/min, determine the total Cardiac Output:

  1. 5.2 L/min
  2. 5 L/min
  3. 14.5 L/min
  4. 52 L/min
Show answer and explanation

Answer: (A) 5.2 L/min

Cardiac Output = Heart Rate (HR) × Stroke Volume (SV) = 65 × 80 mL/min = 5200 mL/min = 5.2 L/min.

Quick tip: Cardiac output is normally around 5 Liters per minute for a healthy adult.

easy

12. Plasma without the clotting factors is called:

  1. Haemoglobin
  2. Serum
  3. Lymph
  4. Tissue fluid
Show answer and explanation

Answer: (B) Serum

Plasma is a straw-coloured viscous fluid forming about 55 per cent of blood. Plasma without clotting factors is called serum.

NCERT Class 11

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