Body Fluids and Circulation

40 NEET-UG practice questions on Body Fluids and Circulation, part of Zoology. The first 25 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

1. Question 1 · Hard

   Assertion A: Amphibians show incomplete double circulation. Reason R: Their two atria pour oxygenated and deoxygenated blood into a single ventricle, where the two get mixed. Choose the correct answer.

   1. AA is correct but R is not correct
   2. BBoth A and R are correct and R is the correct explanation of A
   3. CA is not correct but R is correct
   4. DBoth A and R are correct but R is not the correct explanation of A

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   Answer: B · Both A and R are correct and R is the correct explanation of A

   Both are true, and R explains A. The single ventricle mixes the two streams, so separation is incomplete. Birds and mammals have two ventricles that keep them apart.

   • A: R is true of the amphibian heart.
   • C: A is true of amphibians.
   • D: R gives the cause of the incomplete circulation.

   Remember this

   Fishes have single circulation, amphibians and most reptiles incomplete double, and birds and mammals complete double circulation.

2. Question 2 · Medium

   Match List-I with List-II. List-I (leucocyte) A. Neutrophil B. Basophil C. Eosinophil D. Lymphocyte List-II (role) I. Immune responses as B and T forms II. Most abundant, and phagocytic III. Linked with allergic reactions IV. Secretes histamine, serotonin and heparin

   1. AA-II, B-IV, C-III, D-I
   2. BA-IV, B-II, C-III, D-I
   3. CA-I, B-IV, C-III, D-II
   4. DA-II, B-III, C-IV, D-I

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   Answer: A · A-II, B-IV, C-III, D-I

   Neutrophils are the most abundant leucocytes and destroy foreign organisms by phagocytosis. Basophils secrete inflammatory substances, eosinophils resist infection and act in allergy, and lymphocytes carry out immunity.

   • B: This swaps neutrophil and basophil roles.
   • C: This swaps neutrophil and lymphocyte roles.
   • D: This swaps basophil and eosinophil roles.

   Remember this

   Neutrophils are most abundant (60-65 per cent); basophils are least abundant (0.5-1 per cent).

3. Question 3 · Hard

   Given below are two statements: Statement I: The first heart sound is caused by the closure of the semilunar valves. Statement II: Atrial systole accounts for about 70 per cent of ventricular filling. Choose the correct answer.

   1. AStatement I is correct but Statement II is incorrect
   2. BStatement I is incorrect but Statement II is correct
   3. CBoth Statement I and Statement II are incorrect
   4. DBoth Statement I and Statement II are correct

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   Answer: C · Both Statement I and Statement II are incorrect

   The first sound, lub, comes from closure of the tricuspid and bicuspid valves; the second, dub, from the semilunar valves. Atrial systole adds only about 30 per cent to ventricular filling.

   • A: Statement I swaps the causes of the two sounds.
   • B: Statement II inflates the share of atrial systole.
   • D: Both statements swap the actual facts.

   Remember this

   Lub is closure of AV valves; dub is closure of semilunar valves.

4. Question 4 · Easy

   Deposits of calcium, fat, cholesterol and fibrous tissue narrow the lumen of coronary arteries in

   1. Aatherosclerosis
   2. Bhypertension
   3. Cangina
   4. Dheart failure

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   Answer: A · atherosclerosis

   Coronary artery disease, often called atherosclerosis, narrows the vessels that supply the heart through such deposits.

   • B: Hypertension is blood pressure persistently at 140/90 mm Hg or higher.
   • C: Angina is the chest pain, not the deposit.
   • D: Heart failure is failure to pump enough blood.

   Remember this

   Angina is the chest pain of low oxygen to heart muscle; heart failure is not the same as cardiac arrest.

5. Question 5 · Medium

   At rest, each ventricle of an adult ejects 70 mL of blood per beat, and the heart beats 80 times every minute. How much blood does each ventricle pump out per minute?

   1. A5.6 L/min
   2. B56 L/min
   3. C0.56 L/min
   4. D5.0 L/min

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   Answer: A · 5.6 L/min

   Cardiac output = stroke volume × heart rate = 70 × 80 = 5600 mL/min = 5.6 L/min. Checking another way, 7 × 8 = 56, and 56 × 100 mL = 5.6 L.

   • B: This slips a decimal place while converting to litres.
   • C: This slips a decimal place while converting to litres.
   • D: This is the textbook average, not this calculation.

   Remember this

   Cardiac output is stroke volume times heart rate, about 5 L/min on average at rest.

6. Question 6 · Easy

   Which part of the nodal tissue generates the maximum number of action potentials and sets the rhythm of the heart?

   1. ASino-atrial node
   2. BAtrio-ventricular node
   3. CBundle of His
   4. DPurkinje fibres

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7. Question 7 · Medium

   Arrange the components in the order in which the wave of excitation passes through them. A. Atrio-ventricular bundle B. Atrio-ventricular node C. Purkinje fibres D. Sino-atrial node

   1. AD, B, C, A
   2. BD, B, A, C
   3. CD, A, B, C
   4. DB, D, A, C

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8. Question 8 · Medium

   Match List-I with List-II. List-I (part of ECG) A. P-wave B. QRS complex C. T-wave D. End of the T-wave List-II (event) I. Ventricular repolarisation II. Atrial depolarisation III. End of systole IV. Ventricular depolarisation

   1. AA-II, B-IV, C-I, D-III
   2. BA-II, B-I, C-IV, D-III
   3. CA-IV, B-II, C-I, D-III
   4. DA-II, B-IV, C-III, D-I

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9. Question 9 · Hard

   Consider these statements on blood: A. An enzyme complex, thrombokinase, is needed to convert inactive prothrombin into active thrombin. B. Thrombin converts fibrin into inactive fibrinogen. C. Erythroblastosis foetalis can arise when the mother is Rh-positive and the foetus Rh-negative. D. Serum is plasma that still contains its clotting factors. Choose the correct answer.

   1. AA and B only
   2. BA only
   3. CA and D only
   4. DA, C and D only

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10. Question 10 · Easy

    Which plasma proteins mainly help in osmotic balance?

    1. AGlobulins
    2. BHaemoglobins
    3. CFibrinogens
    4. DAlbumins

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11. Question 11 · Medium

    On an ECG of a resting person, successive R peaks are 0.75 s apart. What is the heart rate?

    1. A72 beats per minute
    2. B80 beats per minute
    3. C45 beats per minute
    4. D75 beats per minute

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12. Question 12 · Medium

    The figure traces blood through the four chambers of the human heart. Match each chamber with the valve guarding its exit. Match List-I with List-II. List-I (chamber) A. Chamber P B. Chamber Q C. Chamber R D. Chamber S List-II (valve at the exit) I. Bicuspid valve II. Semilunar valve at the aorta III. Tricuspid valve IV. Semilunar valve at the pulmonary artery

    

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    1. AA-III, B-IV, C-I, D-II
    2. BA-III, B-II, C-I, D-IV
    3. CA-IV, B-III, C-II, D-I
    4. DA-I, B-II, C-III, D-IV

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13. Question 13 · Medium

    Consider the standard ECG trace drawn in the figure and read these statements: A. Wave W represents depolarisation of the atria. B. Complex X initiates the contraction of the ventricles. C. The end of wave Y marks the end of ventricular systole. D. This trace gives a heart rate of 75 beats per minute. Choose the correct answer.

    

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    1. AA and C only
    2. BA, B, C and D
    3. CB, C and D only
    4. DA, B and C only

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14. Question 14 · Medium

    On an ECG strip of a resting adult, 18 QRS complexes are counted in 15 seconds. What is the heart rate?

    1. A54 beats per minute
    2. B18 beats per minute
    3. C90 beats per minute
    4. D72 beats per minute

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15. Question 15 · Easy

    Which leucocytes are the most abundant, forming about 60-65 per cent of the total WBCs?

    1. ALymphocytes
    2. BBasophils
    3. CEosinophils
    4. DNeutrophils

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16. Question 16 · Hard

    At the very start of ventricular systole, before blood leaves the ventricles, what is the state of the heart valves?

    1. ATricuspid and bicuspid valves closed; semilunar valves closed
    2. BTricuspid and bicuspid valves open; semilunar valves closed
    3. CTricuspid and bicuspid valves open; semilunar valves open
    4. DTricuspid and bicuspid valves closed; semilunar valves open

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17. Question 17 · Medium

    Match List-I with List-II. List-I (vessel or system) A. Pulmonary artery B. Pulmonary veins C. Hepatic portal vein D. Coronary system List-II (role) I. Carries blood from the intestine to the liver before it enters systemic circulation II. Brings oxygenated blood from the lungs to the left atrium III. Circulates blood to and from the cardiac musculature IV. Takes deoxygenated blood from the right ventricle to the lungs Choose the correct answer.

    1. AA-II, B-IV, C-I, D-III
    2. BA-IV, B-II, C-I, D-III
    3. CA-II, B-IV, C-III, D-I
    4. DA-IV, B-II, C-III, D-I

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18. Question 18 · Medium

    An Rh-negative mother has just delivered her first child, who is Rh-positive. To protect her next Rh-positive foetus from erythroblastosis foetalis, she should be given, immediately after this delivery,

    1. Aanticoagulants
    2. Banti-Rh antibodies
    3. CRh antigens
    4. DRh-positive blood

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19. Question 19 · Easy

    Repeated checks show that a person's blood pressure is 140/90 mm Hg or higher. This condition is called

    1. Aangina pectoris
    2. Bheart failure
    3. Chypertension
    4. Dcoronary artery disease

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20. Question 20 · Medium

    Arrange these steps of blood clotting in the correct sequence. A. Thrombokinase converts prothrombin into thrombin. B. Thrombin converts fibrinogen into fibrin. C. An injury stimulates platelets to release factors that start the cascade. D. Fibrin threads trap dead and damaged formed elements, forming a clot. Choose the correct order.

    1. AC, A, B, D
    2. BC, A, D, B
    3. CA, C, B, D
    4. DC, B, A, D

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21. Question 21 · Medium

    About the formed elements of human blood: A. A healthy adult man has on average 5 to 5.5 million RBCs per mm³ of blood. B. RBCs live for about 120 days and are then destroyed in the spleen. C. Blood normally contains 6000-8000 leucocytes per mm³. D. Platelets are cell fragments produced from lymphocytes. Which of these are correct?

    1. AA, B, C and D
    2. BA and B only
    3. CB, C and D only
    4. DA, B and C only

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22. Question 22 · Medium

    In a standard ECG, the end of the T-wave marks the

    1. Astart of atrial depolarisation
    2. Bend of atrial systole
    3. Cend of ventricular systole
    4. Dstart of ventricular depolarisation

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23. Question 23 · Medium

    Given below are two statements: Statement I: In crocodiles, oxygenated and deoxygenated blood mix in a single ventricle. Statement II: In birds and mammals, the systemic and pulmonary circulations are two separate pathways. Choose the correct answer.

    1. ABoth Statement I and Statement II are incorrect
    2. BStatement I is incorrect but Statement II is correct
    3. CBoth Statement I and Statement II are correct
    4. DStatement I is correct but Statement II is incorrect

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24. Question 24 · Easy

    Which leucocytes, forming 2-3 per cent of the total, resist infections and are also associated with allergic reactions?

    1. ABasophils
    2. BLymphocytes
    3. CMonocytes
    4. DEosinophils

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25. Question 25 · Medium

    Arrange these events of blood clotting in the correct order. A. Thrombin converts fibrinogen into fibrin. B. An injury stimulates platelets to release certain factors. C. The enzyme complex thrombokinase forms through a cascade of reactions. D. Prothrombin is converted into thrombin.

    1. AB, C, A, D
    2. BC, B, D, A
    3. CB, D, C, A
    4. DB, C, D, A

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