NEET ZoologyUpdated 19 Oct 2026

Body Fluids and Circulation: NEET PYQs and weightage

Body Fluids and Circulation carries 6.0 of 100 Zoology marks in NEET by past-paper share: 39 of the 648 tagged NEET Zoology PYQs in the ViJEEta bank (NEET 2013–2026). It ranks 7 of 17 Zoology chapters.

Removed from NEET in this chapter: Foetal circulation, Portal systems. Still in NCERT and school exams, not asked in NEET now.

Take the 25-question Body Fluids and Circulation test Key facts ↓All NEET Zoology chapters

6.0/100 Weight in Zoology

Exam importance (4/5, by past-paper share)

39 NEET PYQs

526 Practice questions

462 With measured difficulty

How the weight is computed: this chapter's tagged NEET PYQs divided by all tagged NEET Zoology PYQs in the bank (39 of 648), times 100, with repeated questions counted once. The bank does not store the year of each NEET question, so none is printed. Computed from the bank at build time. Updated 19 Oct 2026.

Body Fluids and Circulation: key facts for NEET

16 facts the paper keeps asking, each with how it is asked. Copy it onto one page of your notebook: that page is this chapter's handbook.

Plasma
Plasma makes up $\sim 55%$ of blood ( $90$ – $92%$ water, $6$ – $8%$ proteins); fibrinogen helps clotting, globulins help defence, albumins keep osmotic balance.
Asked as: match the plasma protein to its role, or "plasma minus clotting factors = ?" (serum).
Formed elements and RBCs
Formed elements are $\sim 45%$ of blood; RBCs number $5$ – $5.5$ million $mm^{- 3}$ , are biconcave and lack a nucleus in most mammals, and form in red bone marrow in adults.
Asked as: "RBCs in adults are formed in?" or a statement on enucleate, biconcave RBCs.
Haemoglobin and RBC life span
Haemoglobin is $12$ – $16 g$ per $100 ml$ of blood; an RBC lives about $120$ days and is destroyed in the spleen, the "graveyard of RBCs".
Asked as: RBC life span or the site of RBC destruction.
WBC count and types
WBCs number $6000$ – $8000 mm^{- 3}$ ; granulocytes are neutrophils, eosinophils and basophils; agranulocytes are lymphocytes and monocytes.
Asked as: "Which one is an agranulocyte?" (lymphocyte/monocyte).
Neutrophils and basophils
Neutrophils are the most numerous WBCs ( $60$ – $65%$ ) and basophils the fewest ( $0.5$ – $1%$ ); basophils secrete histamine, serotonin and heparin.
Asked as: arrange WBCs by percentage, or name the cell that releases histamine.
WBC functions
Neutrophils and monocytes ( $6$ – $8%$ ) are phagocytic; eosinophils ( $2$ – $3%$ ) resist infection and are linked to allergy; B and T lymphocytes ( $20$ – $25%$ ) give immune responses.
Asked as: match the WBC to its function, e.g. eosinophil $\to$ allergic reaction.
Platelets
Platelets (thrombocytes) are cell fragments made from megakaryocytes; there are $1.5$ – $3.5$ lakh $mm^{- 3}$ , and too few platelets cause clotting disorders.
Asked as: "Platelets are produced from?" (megakaryocytes).
ABO blood groups
Group AB has both A and B antigens but no antibodies, so it is the universal recipient; group O has no antigens but both antibodies, so it is the universal donor.
Asked as: antigen-antibody table rows, or which groups can donate to A (A, O).
Rh factor
About $80%$ of humans are Rh $^{+}$ ve; erythroblastosis foetalis occurs when an Rh $^{-}$ ve mother carries an Rh $^{+}$ ve foetus, usually in a later pregnancy.
Asked as: how to prevent it (give anti-Rh antibodies to the mother right after the first delivery).
Coagulation of blood
$Prothrombin thrombokinase Thrombin$
$Fibrinogen thrombin Fibrin threads (C a^{2 +} ions essential)$
In clotting, thrombokinase turns prothrombin into thrombin, and thrombin turns fibrinogen into fibrin threads; $C a^{2 +}$ ions are essential.
Asked as: order the clotting steps, or name the enzyme that converts fibrinogen.
Lymph
Lymph is colourless and carries lymphocytes, nutrients and hormones; fats are absorbed into lymph through the lacteals of intestinal villi.
Asked as: "Fat absorption occurs through?" (lacteals), or how lymph differs from blood.
Circulation and heart chambers
Arthropods and molluscs have open circulation and annelids and chordates have closed; fish have $2$ chambers, amphibians and reptiles (except crocodiles) have $3$ , and crocodiles, birds and mammals have $4$ .
Asked as: "Which reptile has a 4-chambered heart?" (crocodile), or single vs incomplete double circulation.
Heart valves
The tricuspid valve guards the right AV opening, the bicuspid (mitral) valve guards the left, and semilunar valves guard the pulmonary artery and the aorta.
Asked as: match each valve to its location.
Conducting system of the heart
$SAN \to AVN \to AV bundle (bundle of His) \to right and left bundle branches \to Purkinje fibres$
The SAN sits in the right upper corner of the right atrium and is the pacemaker ( $70$ – $75$ action potentials $min^{- 1}$ ); the AVN sits in the lower left corner of the right atrium; the impulse goes SAN $\to$ AVN $\to$ AV bundle (bundle of His) $\to$ right and left bundle branches $\to$ Purkinje fibres.
Asked as: "Pacemaker of the heart is?", or the order of impulse conduction.
Cardiac cycle and cardiac output
$Cardiac output = stroke volume \times heart rate \approx 5 L min^{- 1}$
One cardiac cycle lasts $0.8 s$ ; stroke volume is $\sim 70 mL$ ; cardiac output $=$ stroke volume $\times$ heart rate $\approx 5 L/min$ ; atrial systole adds $\sim 30%$ to ventricular filling.
Asked as: calculate cardiac output, or the duration of a cardiac cycle at $72$ beats/min.
ECG waves
On an ECG, the P-wave is atrial depolarisation, QRS is ventricular depolarisation and the T-wave is ventricular repolarisation; systole ends at the end of the T-wave.
Asked as: match the wave to the event, or "Heart rate is counted from?" (QRS complexes).

Trap

"lub" (the first sound) is the closure of the tricuspid and bicuspid (AV) valves at the start of ventricular systole, and "dub" (the second sound) is the closure of the semilunar valves. Students swap the two, and they also put the tricuspid valve on the left side.

How does NEET ask Body Fluids and Circulation?

8 real previous-year questions from this chapter, as printed in the paper, each with its worked solution. Answer the first one here with no sign-in.

Q1ZoologyNEET UG PYQComposition of Blood

Try right here · No sign-in

Name the blood cells, whose reduction in number can cause clotting disorder, leading to excessive loss of blood from the body.

Answer key (C) & worked solution

Correct answer: Option C

Thrombocytes are also called platelets. They are the vital component of blood. It's basic function is to stop bleeding from injured blood vessels by clumping and clotting blood vessels. Reduction in the number of platelets causes clotting disorder and thus loss of blood from the body. Hence, the correct option is c.

Q2ZoologyNEET UG PYQElectrocardiograph (ECG)

Match List I with List II: List IList IIA.P-waveI.Beginning of systoleB.Q-wave II.Repolarisation of ventriclesC.QRS III.Depolarisation of complex atriaD.T-wave IV.Depolarisation of ventricles Choose the correct answer from the options given below:

AA–IV, B–III, C–II, D–I

BA–II, B–IV, C–I, D–III

CA–I, B–II, C–III, D–IV

DA–III, B–I, C–IV, D–II

Answer key (D) & worked solution

Correct answer: Option D

List IList IIA.P-waveIII.Depolarisation of complex atriaB.Q-wave I.Beginning of systoleC.QRS IV.Depolarisation of ventriclesD.T-wave II.Repolarisation of ventricles

Q3ZoologyNEET UG PYQComposition of Blood

Adult human RBCs are enucleated. Which of the following statement(s) is/are the most appropriate explanation for this feature? (a) They do not need to reproduce (b) They are somatic cells (c) They do not metabolize (d) All their internal space is available for oxygen transport

A(a), (c) and (d)

B(b) and (c)

COnly (d)

DOnly (a)

Answer key (C) & worked solution

Correct answer: Option C

In human RBCs, the nucleus degenerates during maturation which provides more space for oxygen-carrying pigment (Haemoglobin). It lacks most of the cell organelles including mitochondria so respires anaerobically and does not show any metabolic activity and multiplication.

Q4ZoologyNEET UG PYQPortal systems

In frog, the Renal system is a special venous connection that acts to link:

AKidney and intestine

BKidney and lower part of body

CLiver and intestine

DLiver and Kidney

Answer key (B) & worked solution

Correct answer: Option B

Renal Portal System is a special vascular connection that connects the kidneys to the lower parts of the body of a frog.

Q5ZoologyNEET UG PYQComposition of Blood

Match the items given in column I with those in Column II and select the correct option given below. Column IColumn II(a)Fibrinogen(i)Osmotic balance(b)Globulin(ii)Blood clotting(c)Albumin(iii)Defence mechanism

Aa → (i); b → (ii); c → (iii)

Ba → (i); b → (iii); c → (ii)

Ca → (iii); b → (ii); c → (i)

Da → (ii); b → (iii); c → (i)

Answer key (D) & worked solution

Correct answer: Option D

Fibrinogen forms fibrin strands during coagulation. These strands form a network and the meshes inside which blood cells are trapped, this structure finally forms a clot. Globulins are globular proteins. Some globulins are produced in the liver, while others are made by the immune system. Antibodies are derived from the Globulin fraction of plasma proteins which means globulins are involved in defense mechanisms. Albumin is another plasma protein mainly responsible for maintaining osmotic balance.

Q6ZoologyNEET UG PYQComposition of Blood

Which of the following statements are correct? A. Basophils are the 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:

AC and E only

BB and C only

CA and B only

DD and E only

Answer key (B) & worked solution

Correct answer: Option B

A. Neutrophils are the most abundant cells (60-65 per cent) of the total WBCs. D. Monocytes have kidney-shaped nucleus. E. Basophils are granulocytes.

Q7ZoologyNEET UG PYQCoagulation of Blood

Which enzyme is responsible for the conversion of inactive fibrinogens to fibrins?

AEpinephrine

BThrombokinase

CThrombin

DRenin

Answer key (C) & worked solution

Correct answer: Option C

Fibrins are formed by the conversion of inactive fibrinogens in the plasma by the enzyme thrombin. Thrombins, in turn, are formed from another inactive substance present in the plasma called prothrombin. An enzyme complex, thrombokinase, is required for the above reaction. This complex is formed by a series of linked enzymatic reactions (cascade process) involving a number of factors present in the plasma in an inactive state. Epinephrine also known as adrenaline is rapidly secreted in response to stress of any kind and during emergency situations and is called emergency hormones or hormones of Fight or Flight. Renin enzyme secreted by the kidney (and also, possibly, by the placenta) that is part of a physiological system that regulates blood pressure. In the blood, renin acts on a protein known as angiotensinogen, resulting in the release of angiotensin I.

Q8ZoologyNEET UG PYQHuman Circulatory System

Select the correct statements regarding cell membrane in eukaryotic cell. A. Membrane of human RBCs has approximately

52%

protein. B. Major phospholipids are arranged in a bilayer. C. Extensions of the plasma membrane into the cell form mesosomes. D. Tails towards the inner part of lipids are hydrophobic and thus protected from aqueous medium. E. Glycocalyx is present on the outer surface of the plasma membrane.

Choose the correct answer from the options given below:

AA, C and E only

BB, C and E only

CC, D and E only

DA, B and D only

Answer key (D) & worked solution

Correct answer: Option D

• In prokaryotes, extensions of plasma membrane into the cell form mesosomes. Eukaryotes lack such structure. - Glycocalyx is present on the outer surface of the plasma membrane in prokaryotes. Eukaryotes do not have glycocalyx.

Hence, only statement A, B and D are correct.

Which topics in Body Fluids and Circulation carry the most questions?

The 12 busiest of 15 topics, by tagged PYQs, then practice questions. Counted from the bank. Updated 19 Oct 2026.

Topic	PYQs	Practice questions
Composition of Blood	10	98
Blood Groups	7	55
Human Circulatory System	5	98
Electrocardiograph (ECG)	4	38
Circulatory Pathways	4	24
Cardiac Cycle	3	50
Regulation of Cardiac Activity	2	36
Disorders of Circulatory System	1	36
Coagulation of Blood	1	33
Lymph (Tissue Fluid)	1	21
Portal systemsNot in NEET now	1	7
Double Circulation	0	13

Why does Body Fluids and Circulation show "–" until you answer 3 questions?

Unknown is not zero. Until you answer at least 3 graded questions in Body Fluids and Circulation, ViJEEta shows – instead of a zero or a 50% default. Book exercises can raise chapter mastery up to 0.60, adaptive practice up to 0.75, and only a timed chapter test or mock can certify 0.80 and above.

How ViJEEta scores you

What happens when you test Body Fluids and Circulation?

Every chapter test is 25 questions. It starts at moderate difficulty and adapts after each saved answer. If you open a solution before answering, that attempt earns no credit, so your mastery stays honest.

Start the Body Fluids and Circulation test

Chapters either side of Body Fluids and Circulation by weight

Evolution Weight 7.6/100 Human Health and Disease Weight 6.9/100 Chemical Coordination and Integration Weight 5.6/100 Breathing and Exchange of Gases Weight 5.2/100

Body Fluids and Circulation: NEET PYQs and weightage

Body Fluids and Circulation: key facts for NEET

Plasma

Formed elements and RBCs

Haemoglobin and RBC life span

WBC count and types

Neutrophils and basophils

WBC functions

Platelets

ABO blood groups

Rh factor

Coagulation of blood

Lymph

Circulation and heart chambers

Heart valves

Conducting system of the heart

Cardiac cycle and cardiac output

ECG waves

How does NEET ask Body Fluids and Circulation?

Which topics in Body Fluids and Circulation carry the most questions?

Why does Body Fluids and Circulation show "–" until you answer 3 questions?

What happens when you test Body Fluids and Circulation?

Chapters either side of Body Fluids and Circulation by weight