Body Fluids and Circulation: the heart in the right order

Free questions

30 solved MCQs, answer marked and reasoning written out

Every question below is free to read — no sign-up, no email. 3 of them are real questions from past NEET papers. The other 215 questions in this chapter are in the book and in practice access.

1. Q1 Multi-statement analysis

   Vertebrate hearts: (i) fishes have a 2-chambered heart (ii) amphibians and reptiles (except crocodiles) have a 3-chambered heart (iii) crocodiles, birds and mammals possess a 4-chambered heart (iv) all reptiles have a 4-chambered heart. How many are correct?

   1. 1.One
   2. 2.Two
   3. 3.ThreeCorrect answer
   4. 4.Four

   Why option 3 is the answer

   The trap: (i)–(iii) correct; only CROCODILES among reptiles have a 4-chambered heart, so (iv) is wrong.

   What this is testing: how heart chambers differ across vertebrate classes.

   (i)–(iii) are correct: fishes have two chambers, amphibians and most reptiles have three, and crocodiles along with birds and mammals have four.

   (iv) is the trap. It stretches the crocodile exception in (iii) to cover every reptile. Lizards, snakes and turtles are three-chambered; crocodiles alone among reptiles have a complete four-chambered heart. Whenever a statement says "all" right after a sentence names one exception, check whether it has quietly erased that exception.

   So three are correct.

   Two, three, then four as you climb the vertebrates - with the crocodile as the one reptile that jumps ahead to four.

   NCERT Class 11 Biology, page 197

2. Q2 Multi-statement analysis

   Incomplete double circulation: (i) occurs in amphibians and reptiles (ii) the left atrium receives oxygenated blood (iii) the right atrium gets deoxygenated blood (iv) the two do not mix at all. How many are correct?

   1. 1.One
   2. 2.Two
   3. 3.ThreeCorrect answer
   4. 4.Four

   Why option 3 is the answer

   The trap: (i)–(iii) correct; the bloods DO get mixed in the single ventricle, so (iv) is wrong.

   What this is testing: what "incomplete" double circulation actually means in amphibians and reptiles.

   (i)–(iii) are correct: this pattern occurs in amphibians and reptiles, the left atrium receives oxygenated blood, and the right atrium receives deoxygenated blood.

   (iv) is the trap, and it contradicts the word "incomplete" right in the question's own name for this pattern. With only one ventricle receiving blood from both atria, the two bloods DO mix there to some extent — that partial mixing is exactly why the separation is called incomplete rather than complete.

   So three are correct.

   Incomplete is the operative word. The blood is kept apart at the atria and then mixed again in the single ventricle.

   NCERT Class 11 Biology, page 197

3. Q3 Multi-statement analysis

   Erythroblastosis foetalis: (i) arises from Rh incompatibility between an Rh-negative mother and an Rh-positive foetus (ii) the two bloods are well separated by the placenta in the first pregnancy (iii) during delivery of the first child maternal blood may be exposed to foetal Rh-positive blood (iv) it affects the first child most severely. How many are correct?

   1. 1.One
   2. 2.Two
   3. 3.ThreeCorrect answer
   4. 4.Four

   Why option 3 is the answer

   The trap: (i)–(iii) correct; the danger arises in SUBSEQUENT pregnancies, not the first, so (iv) is wrong.

   What this is testing: why erythroblastosis foetalis is a risk for later pregnancies, not the first.

   (i)–(iii) are correct: it arises from Rh incompatibility between an Rh-negative mother and Rh-positive foetus, the two bloods stay separated by the placenta through the first pregnancy, and it is only during delivery of the first child that maternal blood can be exposed to the foetus's Rh-positive blood.

   (iv) is the trap. Because that first exposure happens only at delivery, the first child is normally unaffected — it is a SUBSEQUENT Rh-positive pregnancy that erythroblastosis foetalis threatens, once the mother has already made anti-Rh antibodies.

   So three are correct.

   The first child is spared because the two bloods never meet until delivery. Everything about this disease turns on that timing.

   NCERT Class 11 Biology, page 196

4. Q4 Multi-statement analysis

   Regarding a reduction in platelet number: (i) it can lead to clotting disorders (ii) it leads to excessive loss of blood from the body (iii) platelets release substances involved in coagulation (iv) it leads to anaemia. How many are correct?

   1. 1.One
   2. 2.Two
   3. 3.ThreeCorrect answer
   4. 4.Four

   Why option 3 is the answer

   The trap: (i)–(iii) correct; a fall in platelets causes bleeding disorders, not anaemia, so (iv) is wrong.

   What this is testing: what actually happens when platelet numbers fall.

   (i)–(iii) are correct: a fall in platelets can cause clotting disorders, leads to excessive blood loss, and platelets are the cells that release substances needed for coagulation.

   (iv) is the trap. Low platelets cause bleeding problems, not anaemia — anaemia is a shortage of RBCs or haemoglobin, an entirely different formed element with an entirely different job. The question is testing whether you keep platelet disorders and RBC disorders in separate boxes.

   So three are correct.

   Fewer platelets means less clotting and more bleeding. The chain runs one way, and any option reversing it is wrong.

   NCERT Class 11 Biology, page 195

5. Q5 Multi-statement analysis

   Regarding haemoglobin: (i) it is a red coloured, iron containing complex protein (ii) a healthy individual has 12-16 g of haemoglobin in every 100 mL of blood (iii) it plays a significant role in the transport of respiratory gases (iv) it is present in the plasma. How many are correct?

   1. 1.One
   2. 2.Two
   3. 3.ThreeCorrect answer
   4. 4.Four

   Why option 3 is the answer

   The trap: (i)–(iii) correct; haemoglobin lies within the RBCs, not free in plasma, so (iv) is wrong.

   What this is testing: what haemoglobin is, what it does, and exactly where it sits in the blood.

   (i)–(iii) are correct: haemoglobin is a red, iron-containing protein, a healthy person has 12-16 g of it per 100 mL of blood, and it carries respiratory gases.

   (iv) is the trap. Haemoglobin is packed inside the RBCs, not dissolved free in the plasma — plasma carries its own separate set of proteins (fibrinogen, globulins, albumins). Placing haemoglobin in plasma is the same slip tested elsewhere in this chapter under plasma proteins.

   So three are correct.

   Iron sits at the centre of haemoglobin, which is why iron shortage shows up as anaemia. 12 to 16 g per 100 mL is the figure asked for.

   NCERT Class 11 Biology, page 194

6. Q6 Multi-statement analysis

   Regarding erythroblastosis foetalis: (i) maternal Rh antibodies can leak into the blood of the foetus (ii) they destroy the foetal RBCs (iii) it could cause severe anaemia and jaundice to the baby (iv) it can be avoided by administering anti-Rh antibodies to the mother immediately after the delivery of the first child. How many are correct?

   1. 1.One
   2. 2.Two
   3. 3.Three
   4. 4.FourCorrect answer

   Why option 4 is the answer

   The trap: All four are correct.

   What this is testing: the full chain of events in erythroblastosis foetalis, and how it is prevented.

   All four statements are correct. Maternal Rh antibodies can cross into the foetal blood, destroy the foetal RBCs, and cause severe anaemia and jaundice, and the condition can be prevented by giving the mother anti-Rh antibodies right after the first delivery so she never makes her own.

   Each line follows logically from the one before it, cause leading to effect leading to prevention, with no reversed fact slipped in among them.

   So all four are correct.

   The disease is preventable, and that is the part most often left out. Anti-Rh antibodies given after the first delivery stop it ever starting.

   NCERT Class 11 Biology, page 196

7. Q7 Multi-statement analysis

   Tissue fluid: (i) is formed as blood passes through the capillaries in tissues (ii) contains water and small water-soluble substances (iii) leaves the larger proteins and most formed elements in the blood vessels (iv) has a mineral distribution quite different from plasma. How many are correct?

   1. 1.One
   2. 2.Two
   3. 3.ThreeCorrect answer
   4. 4.Four

   Why option 3 is the answer

   The trap: (i)–(iii) correct; tissue fluid has the SAME mineral distribution as plasma, so (iv) is wrong.

   What this is testing: how tissue fluid forms from plasma, and what it keeps versus what it loses.

   (i)–(iii) are correct: tissue fluid forms as blood passes through capillaries, it carries water and small water-soluble substances, and it leaves the larger proteins and most formed elements behind in the vessels.

   (iv) is the trap. Tissue fluid has the SAME mineral distribution as plasma, not a different one — only the large proteins and cells are filtered out at the capillary wall, while small dissolved minerals pass through freely into the tissue fluid unchanged.

   So three are correct.

   Capillary walls let water and small solutes through but hold back proteins and cells. That filter is what makes tissue fluid different from blood.

   NCERT Class 11 Biology, page 197

8. Q8 Multi-statement analysis

   Functions of plasma proteins: (i) fibrinogens are needed for coagulation of blood (ii) globulins are primarily involved in defense mechanisms (iii) albumins help in osmotic balance (iv) albumins are needed for clotting. How many are correct?

   1. 1.One
   2. 2.Two
   3. 3.ThreeCorrect answer
   4. 4.Four

   Why option 3 is the answer

   The trap: (i)–(iii) correct; clotting requires FIBRINOGEN, not albumin, so (iv) is wrong.

   What this is testing: which plasma protein does which job — coagulation, defence, or osmotic balance.

   (i)–(iii) are correct: fibrinogen handles coagulation, globulins are involved in defence, and albumins maintain osmotic balance.

   (iv) is the trap. Clotting needs FIBRINOGEN, already assigned correctly in (i) — albumin's job is osmotic balance, not clotting. The statement takes a function that belongs to one protein and reassigns it to another, testing whether you have memorised the three jobs as a fixed set rather than interchangeable labels.

   So three are correct.

   Fibrinogen clots, globulin defends, albumin holds water in the vessel. One protein, one job, and the three are rarely asked apart.

   NCERT Class 11 Biology, page 194

9. Q9 Assertion and Reason

   AssertionLymph is an important carrier for nutrients and hormones.

   ReasonFats are absorbed through lymph in the lacteals present in the intestinal villi.

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

   Why option 2 is the answer

   The trap: Both are true of lymph; fat absorption in the lacteals is a parallel function and does not explain the carriage of nutrients and hormones in general.

   What this is testing: whether the lacteal-fat connection actually explains lymph's broader carrier role.

   Assertion is true: lymph carries nutrients and hormones through the body. Reason is also true — fats are absorbed through lymph via the lacteals in the intestinal villi — but this is only one specific example of fat transport, not the reason lymph in general carries nutrients and hormones throughout the body.

   The reason describes a narrower, separate fact that sits alongside the assertion rather than explaining it.

   Both A and R are true, but R is not the correct explanation of A.

   Fat is one cargo; nutrients and hormones are others. An example of a general claim does not explain the claim.

   NCERT Class 11 Biology, page 197

10. Q10 Assertion and Reason

    AssertionThe tunica media is comparatively thin in the veins.

    ReasonEach artery and vein consists of three layers, the tunica intima, the tunica media and the tunica externa.

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

    Why option 2 is the answer

    The trap: Both are true of blood vessels; the three-layered plan is a parallel structural fact and does not explain the thinness of the venous media.

    What this is testing: whether the general three-layer plan of vessels explains why veins have a thin middle layer.

    Assertion is true: the tunica media, the muscular middle layer, is comparatively thin in veins. Reason is also true — every artery and vein does have three layers, intima, media and externa — but stating that the layers exist does not explain why the media specifically is thinner in veins than in arteries.

    That thinness relates to the lower pressure veins carry, a detail the reason never mentions.

    Both A and R are true, but R is not the correct explanation of A.

    Listing the parts does not explain why one of them is thinner. The answer to that lies in pressure, which neither statement mentions.

    NCERT Class 11 Biology, page 201

11. Q11 Assertion and Reason

    AssertionA special coronary system of blood vessels is present in our body.

    ReasonThe hepatic portal vein carries blood from the intestine to the liver before it is delivered to the systemic circulation.

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

    Why option 2 is the answer

    The trap: Both are true of special vascular connections running in parallel; the hepatic portal system does not explain the coronary system.

    What this is testing: whether the hepatic portal system explains the existence of the separate coronary system.

    Assertion is true: a special coronary system of vessels supplies the heart's own muscle. Reason is also true — the hepatic portal vein does carry blood from the intestine to the liver before it joins general circulation — but this is a different special vascular arrangement entirely, unrelated to why the heart needs its own coronary supply.

    Two true but independent facts about special blood pathways do not explain each other.

    Both A and R are true, but R is not the correct explanation of A.

    Coronary and hepatic portal are two different special circulations. A second example alongside the first is not a reason for it.

    NCERT Class 11 Biology, page 202

12. Q12 Assertion and Reason

    AssertionCalcium ions play a very important role in clotting.

    ReasonFibrins are formed by the conversion of inactive fibrinogens in the plasma by the enzyme thrombin.

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

    Why option 2 is the answer

    The trap: Both are true of coagulation running in parallel; the thrombin reaction does not explain the role of calcium.

    What this is testing: whether the thrombin-fibrinogen step explains calcium's separate role in clotting.

    Assertion is true: calcium ions are essential to coagulation. Reason is also true — fibrin does form when thrombin converts fibrinogen — but this describes a different step of the cascade, one that does not by itself explain what calcium specifically contributes to the overall clotting process.

    Two true facts about the same cascade, sitting at different points in it, do not automatically explain each other.

    Both A and R are true, but R is not the correct explanation of A.

    Both statements describe the same cascade at different points. Sharing a process is not the same as one step causing another.

    NCERT Class 11 Biology, page 196

13. Q13 Assertion and Reason

    AssertionSympathetic neural signals increase the cardiac output.

    ReasonParasympathetic neural signals decrease the rate of heart beat and thereby the cardiac output.

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

    Why option 2 is the answer

    The trap: Both are true of autonomic control; the parasympathetic effect is a parallel opposing fact and does not explain the sympathetic one.

    What this is testing: whether the parasympathetic effect explains the separate, opposite sympathetic effect on cardiac output.

    Assertion is true: sympathetic signals raise cardiac output. Reason is also true — parasympathetic signals do lower heart rate and cardiac output — but this describes the opposing branch of the autonomic system, not the mechanism behind the sympathetic increase stated in the assertion.

    The two branches work in opposite directions, so a true fact about one cannot serve as the explanation for the other.

    Both A and R are true, but R is not the correct explanation of A.

    Accelerator and brake, described side by side. The existence of one branch never explains the action of the other.

    NCERT Class 11 Biology, page 202

14. Q14 Assertion and Reason

    AssertionFibrins are converted into fibrinogens by the enzyme thrombin.

    ReasonFibrins are formed by the conversion of the inactive fibrinogens of the plasma by the enzyme thrombin.

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

    Why option 4 is the answer

    The trap: A is false — the conversion runs from fibrinogen to fibrin; R is true.

    What this is testing: the direction of the fibrinogen-to-fibrin conversion.

    Assertion is false. Thrombin converts fibrinogen into fibrin, not fibrin into fibrinogen — the assertion has the two molecules' names swapped in direction. Reason is true and gives the correct direction: inactive fibrinogen is converted to fibrin by thrombin.

    Reading quickly, the two statements look alike, but the assertion runs the reaction backward while the reason states it forward and correctly.

    A is false but R is true.

    Fibrinogen is the soluble form and fibrin the threads of the clot. The conversion only ever runs from soluble to solid.

    NCERT Class 11 Biology, page 196

15. Q15 Assertion and Reason

    AssertionThe stroke volume of each ventricle during a cardiac cycle is about 5000 mL.

    ReasonDuring a cardiac cycle each ventricle pumps out approximately 70 mL of blood, which is called the stroke volume.

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

    Why option 4 is the answer

    The trap: A is false — 5000 mL is the cardiac output per minute; R is true.

    What this is testing: the difference between stroke volume and cardiac output.

    Assertion is false. Stroke volume per beat is about 70 mL, not 5000 mL — 5000 mL is the CARDIAC OUTPUT, the total pumped per minute across roughly 72 beats. Reason is true and states the correct stroke volume figure.

    The assertion has taken the per-minute total and mislabelled it as the per-beat volume, conflating two figures that differ by a factor of about 72.

    A is false but R is true.

    Seventy millilitres per beat, five litres per minute. Stroke volume is the single beat, cardiac output the whole minute.

    NCERT Class 11 Biology, page 200

16. Q16 Assertion and Reason

    AssertionNeutrophils are the most abundant of the white blood cells.

    ReasonBasophils are the least abundant among the white blood cells.

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

    Why option 2 is the answer

    The trap: Both are true of the WBC differential count running in parallel; the scarcity of basophils does not explain the abundance of neutrophils.

    What this is testing: whether the scarcity of one WBC type explains the abundance of another.

    Assertion is true: neutrophils are the most abundant WBCs, at 60-65 per cent. Reason is also true — basophils are indeed the least abundant, at 0.5-1 per cent — but the two are simply two ends of the same differential count, and one fact does not cause or explain the other; each cell's share is set independently.

    Both A and R are true, but R is not the correct explanation of A.

    Top of the list and bottom of the list. Two ends of one count, and neither position causes the other.

    NCERT Class 11 Biology, page 194

17. Q17 Assertion and Reason

    AssertionBlood is regarded as an epithelial tissue.

    ReasonBlood is a special connective tissue consisting of a fluid matrix, plasma, and formed elements.

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

    Why option 4 is the answer

    The trap: A is false — blood is a CONNECTIVE tissue; R is true.

    What this is testing: which tissue category blood actually belongs to.

    Assertion is false. Blood is a CONNECTIVE tissue, not an epithelial one — epithelial tissue lines and covers surfaces, which is not what blood does. Reason is true and gives the correct classification: blood is a special connective tissue made of the fluid matrix plasma plus the formed elements suspended in it.

    The reason states the fact correctly right where the assertion gets it wrong, so only the reason should be trusted.

    A is false but R is true.

    Epithelium covers and lines surfaces. Blood does neither, which is why it sits with the connective tissues despite being liquid.

    NCERT Class 11 Biology, page 193

18. Q18 Statement I and Statement II

    Statement ILymphocytes are phagocytic cells that destroy foreign organisms.

    Statement IINeutrophils and monocytes are responsible for immune responses.

    1. 1.Both Statement I and Statement II are correct
    2. 2.Both Statement I and Statement II are incorrectCorrect answer
    3. 3.Statement I is correct but Statement II is incorrect
    4. 4.Statement I is incorrect but Statement II is correct

    Why option 2 is the answer

    The trap: Both incorrect — the roles are interchanged: neutrophils and monocytes are phagocytic while B and T lymphocytes are responsible for immune responses.

    What this is testing: whether the phagocytosis and immune-response roles have been assigned to the right WBC types.

    Statement I is incorrect: lymphocytes are not phagocytic; they are responsible for immune responses instead. Statement II is also incorrect: neutrophils and monocytes are the phagocytic cells, not the ones running immune responses.

    The two statements have simply swapped roles between the two cell groups — each sentence describes the other group correctly, which is exactly the trap to catch.

    Both Statement I and Statement II are incorrect.

    Lymphocytes recognise, neutrophils and monocytes eat. Both statements here have the two jobs the wrong way round.

    NCERT Class 11 Biology, page 194

19. Q19 Statement I and Statement II

    Statement IThe tricuspid valve guards the opening between the right atrium and the right ventricle.

    Statement IIThe semilunar valves guard the openings of the ventricles into the pulmonary artery and the aorta.

    1. 1.Both Statement I and Statement II are correctCorrect answer
    2. 2.Both Statement I and Statement II are incorrect
    3. 3.Statement I is correct but Statement II is incorrect
    4. 4.Statement I is incorrect but Statement II is correct

    Why option 1 is the answer

    The trap: Both statements are correct.

    What this is testing: which valve guards which opening in the heart.

    Statement I is correct: the tricuspid valve guards the right atrioventricular opening. Statement II is also correct: the semilunar valves guard the exits of both ventricles into the pulmonary artery and the aorta.

    Together the two statements map out three of the heart's four valve positions accurately, with the AV valve on the right and the arterial exit valves both correctly placed.

    Both Statement I and Statement II are correct.

    Atrioventricular valves between the chambers, semilunar valves at the exits. Four valves, two pairs, each guarding a different kind of opening.

    NCERT Class 11 Biology, page 199

20. Q20 Statement I and Statement II

    Statement IThe first heart sound 'lub' is associated with the closure of the semilunar valves.

    Statement IIThe second heart sound 'dub' is associated with the closure of the tricuspid and bicuspid valves.

    1. 1.Both Statement I and Statement II are correct
    2. 2.Both Statement I and Statement II are incorrectCorrect answer
    3. 3.Statement I is correct but Statement II is incorrect
    4. 4.Statement I is incorrect but Statement II is correct

    Why option 2 is the answer

    The trap: Both incorrect — the two sounds are interchanged.

    What this is testing: which valves closing produce the first heart sound, and which produce the second.

    Both statements are incorrect, in a matched way. The first sound, "lub", comes from closure of the TRICUSPID and BICUSPID valves, not the semilunar valves; the second sound, "dub", comes from closure of the SEMILUNAR valves, not the tricuspid and bicuspid ones.

    The two statements have simply exchanged which valve pair belongs to which sound — a mirror-image swap rather than two independent errors.

    Both Statement I and Statement II are incorrect.

    Lub is the AV valves, dub is the semilunar. Both statements here are wrong, and wrong in the same swapped way, which is itself the clue.

    NCERT Class 11 Biology, page 200

21. Q21 Match the columns

    Match the vessel layer with its composition:

    Column I	Column II
    (a) Tunica intima	(ii) fibrous connective tissue with collagen
    (b) Tunica media	(iii) comparatively thin tunica media
    (c) Tunica externa	(iv) smooth muscle and elastic fibres
    (d) Veins	(i) inner lining of squamous endothelium

    1. 1.(a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)
    2. 2.(a)-(i), (b)-(ii), (c)-(iv), (d)-(iii)
    3. 3.(a)-(i), (b)-(iv), (c)-(ii), (d)-(iii)Correct answer
    4. 4.(a)-(iii), (b)-(iv), (c)-(ii), (d)-(i)

    Why option 3 is the answer

    The trap: The three vessel layers, with a thin media in the veins.

    What this is testing: matching each vessel layer, and the vein's distinctive feature, to its composition.

    The correct match runs in the order given: tunica intima as the inner squamous endothelial lining, tunica media as smooth muscle and elastic fibres, tunica externa as fibrous connective tissue with collagen, veins with a comparatively thin tunica media — option 3.

    Option 1 is the trap: it swaps tunica intima and tunica media, giving the innermost lining a muscular composition that actually belongs to the middle layer.

    Option 3 is correct.

    Inner lining, muscular middle, fibrous outer. Veins carry the same three layers with a thinner middle, because they work at lower pressure.

    NCERT Class 11 Biology, page 201

22. Q22 Match the columns

    Match the circulation with its pathway:

    Column I	Column II
    (a) Pulmonary circulation	(iii) left ventricle to tissues to right atrium
    (b) Systemic circulation	(iv) supplies the cardiac musculature
    (c) Hepatic portal system	(ii) right ventricle to lungs to left atrium
    (d) Coronary system	(i) intestine to liver

    1. 1.(a)-(iii), (b)-(ii), (c)-(i), (d)-(iv)
    2. 2.(a)-(ii), (b)-(iii), (c)-(i), (d)-(iv)Correct answer
    3. 3.(a)-(ii), (b)-(i), (c)-(iii), (d)-(iv)
    4. 4.(a)-(iv), (b)-(iii), (c)-(i), (d)-(ii)

    Why option 2 is the answer

    The trap: Pulmonary, systemic, hepatic portal and coronary circulations.

    What this is testing: matching each circulatory pathway to its correct route.

    The correct match runs in the order given: pulmonary circulation from right ventricle to lungs to left atrium, systemic circulation from left ventricle to tissues to right atrium, hepatic portal system from intestine to liver, coronary system supplying the heart's own muscle — option 2.

    Option 1 is the trap: it swaps pulmonary and systemic circulation, sending the right ventricle's blood to the body tissues instead of the lungs.

    Option 2 is correct.

    Right ventricle to lungs, left ventricle to body, gut to liver, and the heart feeding itself. Four circuits, each named for where it goes.

    NCERT Class 11 Biology, page 202

23. Q23 Match the columns

    Match the disorder with its description:

    Column I	Column II
    (a) Hypertension	(i) acute chest pain from insufficient oxygen
    (b) Coronary artery disease	(ii) heart not pumping effectively enough
    (c) Angina pectoris	(iii) atherosclerosis, narrowed lumen
    (d) Heart failure	(iv) blood pressure of 140/90 or higher

    1. 1.(a)-(iii), (b)-(iv), (c)-(i), (d)-(ii)
    2. 2.(a)-(iv), (b)-(iii), (c)-(i), (d)-(ii)Correct answer
    3. 3.(a)-(iv), (b)-(i), (c)-(iii), (d)-(ii)
    4. 4.(a)-(ii), (b)-(iii), (c)-(i), (d)-(iv)

    Why option 2 is the answer

    The trap: Hypertension, CAD, angina and heart failure defined.

    What this is testing: matching each cardiovascular disorder to its correct description.

    The correct match runs in the order given: hypertension as blood pressure of 140/90 or higher, coronary artery disease as atherosclerosis narrowing the vessel lumen, angina pectoris as acute chest pain from insufficient oxygen to the heart, heart failure as the heart not pumping effectively — option 2.

    Option 1 is the trap: it swaps hypertension and coronary artery disease, defining hypertension by a narrowed lumen instead of a blood pressure reading.

    Option 2 is correct.

    Hypertension is the pressure, atherosclerosis the narrowing, angina the pain, heart failure the pump giving up. One disease often leads to the next.

    NCERT Class 11 Biology, page 203

24. Q24 Match the columns

    Match the neural/hormonal influence with its effect:

    Column I	Column II
    (a) Sympathetic nerves	(iv) auto regulation, myogenic heart
    (b) Parasympathetic nerves	(iii) increase cardiac output
    (c) Adrenal medullary hormones	(ii) increase heart rate and cardiac output
    (d) Nodal tissue	(i) decrease heart rate and cardiac output

    1. 1.(a)-(i), (b)-(ii), (c)-(iii), (d)-(iv)
    2. 2.(a)-(ii), (b)-(iii), (c)-(i), (d)-(iv)
    3. 3.(a)-(iv), (b)-(i), (c)-(iii), (d)-(ii)
    4. 4.(a)-(ii), (b)-(i), (c)-(iii), (d)-(iv)Correct answer

    Why option 4 is the answer

    The trap: Sympathetic raises, parasympathetic lowers, adrenal hormones raise, nodal tissue auto-regulates.

    What this is testing: matching each neural or hormonal influence to its effect on the heart.

    The correct match runs in the order given: sympathetic nerves increase heart rate and cardiac output, parasympathetic nerves decrease them, adrenal medullary hormones increase cardiac output, nodal tissue auto-regulates the myogenic heart — option 4.

    Option 1 is the trap: it swaps sympathetic and parasympathetic, crediting the sympathetic nerves with lowering cardiac output. Sympathetic always speeds the heart up; parasympathetic always slows it down.

    Option 4 is correct.

    Sympathetic speeds up, parasympathetic slows down, adrenaline speeds up, and the nodal tissue keeps the beat regardless. Three outside influences on one self-starting organ.

    NCERT Class 11 Biology, page 202

25. Q25 Exception / incorrect

    Identify the INCORRECT pairing (ECG – event):

    1. 1.P-wave – atrial depolarisation
    2. 2.QRS – ventricular depolarisation
    3. 3.T-wave – ventricular repolarisation
    4. 4.T-wave – atrial depolarisationCorrect answer

    Why option 4 is the answer

    The trap: The P-wave represents atrial depolarisation.

    What this is testing: not letting the T-wave be mistaken for atrial depolarisation.

    P-wave with atrial depolarisation, QRS with ventricular depolarisation, and T-wave with ventricular repolarisation are all correctly paired. The incorrect pairing is T-wave with atrial depolarisation — that event belongs to the P-wave, already correctly listed above; the T-wave instead marks the ventricles recovering, not the atria firing.

    Option 4 is the incorrect pairing.

    P is atrial, QRS and T are both ventricular. The atria get one wave; the ventricles get two.

    NCERT Class 11 Biology, page 201

26. Q26 Exception / incorrect

    All are layers of a blood vessel EXCEPT:

    1. 1.tunica intima
    2. 2.tunica media
    3. 3.tunica cardiacaCorrect answer
    4. 4.tunica externa

    Why option 3 is the answer

    The trap: There is no layer called tunica cardiaca.

    What this is testing: the actual names of the three layers making up a blood vessel wall.

    Tunica intima, tunica media and tunica externa are the genuine three layers of an artery or vein wall, from innermost to outermost. Tunica cardiaca is the exception — no such layer exists in the text; it is an invented name that sounds plausible only because "cardiac" relates to the heart.

    Option 3 is the exception.

    Intima, media, externa - inner, middle, outer, and nothing else. An invented fourth layer is a common way to build a plausible distractor.

    NCERT Class 11 Biology, page 201

27. Q27 Sequence / ordering

    Correct order of layers of a blood vessel from inside outwards:

    1. 1.tunica externa → tunica media → tunica intima
    2. 2.tunica intima → tunica media → tunica externaCorrect answer
    3. 3.tunica media → tunica intima → tunica externa
    4. 4.tunica intima → tunica externa → tunica media

    Why option 2 is the answer

    The trap: Intima (inner) → media (middle) → externa (outer).

    What this is testing: the order of a blood vessel's three wall layers from the lumen outward.

    Reading from the inside of the vessel outward, the order is tunica intima, then tunica media, then tunica externa — option 2, following the layers' names directly: intima means inner, media means middle, externa means outer.

    Option 1 reverses this entirely, starting from the outermost layer and working inward — the exact opposite of how a cross-section of a vessel wall is actually described.

    Option 2 is correct.

    Intima, media, externa - inner, middle, outer. The Latin in the names gives the order without any memorising.

    NCERT Class 11 Biology, page 201

28. Q28 NEET 2022

    Arrange the following formed elements in decreasing order of their abundance in human blood:

    1. 1.Platelets > Erythrocytes > Neutrophils > Eosinophils > Monocytes
    2. 2.Neutrophils > Erythrocytes > Platelets > Monocytes > Eosinophils
    3. 3.Erythrocytes > Neutrophils > Platelets > Eosinophils > Monocytes
    4. 4.Erythrocytes > Platelets > Neutrophils > Monocytes > EosinophilsCorrect answer

    Why option 4 is the answer

    The trap: Erythrocytes vastly outnumber the other elements, followed by platelets, then neutrophils, monocytes and eosinophils among the WBCs.

    What this is testing: ranking the formed elements of blood from most to least abundant.

    The correct order is erythrocytes > platelets > neutrophils > monocytes > eosinophils — option 4, with RBCs vastly outnumbering everything else, and monocytes still outnumbering the rarer eosinophils among WBCs.

    Option 1 wrongly puts platelets ahead of erythrocytes, the most numerous cell of all. Option 2 puts neutrophils ahead of erythrocytes, also wrong. Option 3 swaps the order of monocytes and eosinophils near the bottom of the list.

    RBCs always come first by a huge margin, followed by platelets, then the WBC types in their own internal ranking, neutrophils highest among them and eosinophils near the bottom.

    NCERT Class 11 Biology, page 194

29. Q29 NEET 2019

    What would be the heart rate of a person if the cardiac output is 5 L, the blood volume in the ventricles at the end of diastole is 100 mL, and at the end of ventricular systole is 50 mL?

    1. 1.125 beats per minute
    2. 2.100 beats per minuteCorrect answer
    3. 3.50 beats per minute
    4. 4.75 beats per minute

    Why option 2 is the answer

    The trap: Stroke volume = 100 - 50 = 50 mL; heart rate = cardiac output / stroke volume = 5000/50 = 100 bpm.

    What this is testing: calculating heart rate from cardiac output and ventricular volumes.

    Stroke volume is end-diastolic volume minus end-systolic volume, 100 mL minus 50 mL, giving 50 mL. Heart rate equals cardiac output divided by stroke volume, 5000 mL divided by 50 mL, giving 100 beats per minute — option 2.

    Option 1, 125, option 3, 50, and option 4, 75, would each result from using the wrong stroke volume or dividing incorrectly, rather than from following the two-step calculation through in the right order.

    Work the two steps in sequence, stroke volume first, then heart rate from cardiac output over stroke volume, rather than trying to guess the final number directly.

    NCERT Class 11 Biology, page 200

30. Q30 AIPMT 2012

    A road-accident patient with an unknown blood group needs immediate blood transfusion. A doctor friend at once offers his own blood. What must the donor's blood group have been?

    1. 1.Blood group B
    2. 2.Blood group AB
    3. 3.Blood group A
    4. 4.Blood group OCorrect answer

    Why option 4 is the answer

    The trap: Group O blood, lacking A and B antigens, can be given to a recipient of unknown blood group in an emergency.

    What this is testing: which blood group is safe to give in an emergency transfusion of unknown type.

    Group O blood — option 4 — is what the donor must have had, since O RBCs carry no A or B antigens and so will not trigger an antibody reaction in a recipient of any ABO group, unknown or not.

    Options 1, 2 and 3, groups B, AB and A, each carry at least one antigen (B, both A and B, or A respectively) that could be attacked by antibodies in a mismatched recipient, making them unsafe when the recipient's group is not known.

    O's antigen-free RBCs are exactly what make it the safe emergency choice when there is no time to test the recipient's blood group first.

    NCERT Class 11 Biology, page 195