NEET (UG) · Zoology, Class 11
Body Fluids and Circulation: NEET PYQ, 2018–2026
Body Fluids and Circulation (Zoology, Class 11) has been asked 15 times in the 7 NEET papers from 2018, 2020, 2021, 2023, 2024, 2025 and 2026: about 2.1 questions a paper, 5% of all Zoology questions. It is the 10th most-asked of 15 Zoology chapters. NEET 2026 had 3 from it. Last checked 28 October 2026.
Questions per paper
Year by year.
| Year | Questions |
|---|---|
| 2018 | 2 |
| 2020 | 2 |
| 2021 | 2 |
| 2023 | 2 |
| 2024 | 2 |
| 2025 | 2 |
| 2026 | 3 |
From 2021 to 2024 each paper had 200 questions (a Section B with a choice); the others had 180.
Inside the chapter
Topics asked most.
- Blood composition6
- Cardiac cycle5
- ECG3
- Circulatory disorders1
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10 Body Fluids and Circulation questions to practise.
Our own questions, written in the NEET pattern and checked, each with an explanation. Pick an option to see the answer.
Q1 · Zoology · Body Fluids and Circulation
Platelets, also called thrombocytes, are:
Answer: (A)
Platelets are cell fragments produced from megakaryocytes, which are special cells in the bone marrow. They release a variety of substances, most of which are involved in the coagulation of blood, so a fall in their number leads to clotting disorders.
Q2 · Zoology · Body Fluids and Circulation
On a standard ECG, the interval from the end of the T wave to the start of the next P wave corresponds to which phase of the cardiac cycle?
Answer: (D)
The cardiac cycle has systole and diastole for each chamber. Ventricular systole runs from the QRS to the end of the T wave. The following isoelectric interval, from the T wave end to the next P wave, is ventricular diastole, when the ventricles fill passively and then receive atrial contribution.
Q3 · Zoology · Body Fluids and Circulation
In mitral stenosis, the mitral valve between the left atrium and left ventricle narrows. During ventricular filling in diastole, blood is held back in which chamber, causing the pressure there to rise and congest the pulmonary circulation?
Answer: (C)
Principle: a valve stenosis obstructs flow across that valve, so the pressure builds in the chamber on the upstream side. The mitral valve sits between the left atrium and left ventricle, so during diastole blood piles up in the left atrium. This raises pulmonary venous pressure and causes pulmonary congestion. Identifying the upstream chamber is the key step.
Q4 · Zoology · Body Fluids and Circulation
In a standard ECG, the QRS complex has a larger amplitude than the P wave. What is the main reason?
Answer: (A)
The QRS complex reflects the depolarisation of the ventricles, whose walls are thick and contain a large mass of muscle. The P wave reflects the depolarisation of the thinner atrial walls, which involves less tissue. A larger amount of depolarising muscle produces a larger ECG deflection.
Q5 · Zoology · Body Fluids and Circulation
During the phase of ventricular systole called isovolumetric contraction, which valves are closed?
Answer: (A)
Ventricular systole has two parts. In isovolumetric contraction, the ventricles contract, pressure rises sharply, and volume is unchanged. Ventricular pressure exceeds atrial pressure, so the AV valves close. Ventricular pressure has not yet exceeded the aortic and pulmonary pressures, so the semilunar valves stay shut. Blood only leaves the ventricles once the semilunar valves open, in the ejection phase.
Q6 · Zoology · Body Fluids and Circulation
On a standard ECG, the TP segment is the flat interval between the end of the T wave and the start of the next P wave. Which phase of the cardiac cycle does this segment correspond to?
Answer: (A)
The T wave marks ventricular repolarisation, so the ventricles have finished their electrical cycle by its end. The TP segment is the isoelectric period before the next P wave, when no chamber is depolarising or repolarising. This is ventricular diastole, during which the ventricles relax and fill. Atrial systole is triggered by the P wave, which comes after the TP segment.
Q7 · Zoology · Body Fluids and Circulation
Coronary artery disease (atherosclerosis) is caused by:
Answer: (A)
Coronary artery disease, often referred to as atherosclerosis, affects the vessels that supply blood to the heart muscle. It is caused by deposits of calcium, fat, cholesterol and fibrous tissues, which make the lumen of the arteries narrower.
Q8 · Zoology · Body Fluids and Circulation
On a standard ECG, the interval between two consecutive R peaks (the R-R interval) is 0.8 s. What is the resting heart rate this indicates?
Answer: (B)
The R-R interval is the time between successive ventricular depolarisations, i.e. one complete cardiac cycle. Heart rate is the number of cycles per minute. Rate (beats/min) = 60 ÷ (R-R interval in seconds) = 60 ÷ 0.8 = 75. Check: 75 beats × 0.8 s = 60 s, which is one minute. A quick plausibility check is that a normal resting adult rate of 60 to 100 beats/min corresponds to an R-R interval of roughly 0.6 to 1.0 s.
Q9 · Zoology · Body Fluids and Circulation
Varicose veins develop in the legs when a particular structure in the veins weakens, so blood pools in the veins instead of being pushed back towards the heart. Which structure is this?
Answer: (D)
Principle: venous return from the legs depends on one-way valves inside the veins, aided by skeletal muscle contraction. When these valves weaken, backflow and pooling occur and the veins dilate. The question asks for the structure that fails, which is the venous valves, not the heart valves or arterial wall components.
Q10 · Zoology · Body Fluids and Circulation
Heart failure is a circulatory disorder. Which of the following best describes heart failure?
Answer: (A)
Heart failure means the heart cannot pump blood effectively enough to supply the body's tissues with oxygen and nutrients. It is not the same as cardiac arrest, where the heartbeat stops. The heart may still beat but with reduced output, which can cause breathlessness, fluid accumulation and fatigue. Learn it as a pumping-capacity problem, distinct from rhythm or venous problems.
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All 15 real NEET questions from Body Fluids and Circulation.
The questions from the actual papers, with the official answer and an explanation for each — chapter by chapter, or as full timed papers.
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About Body Fluids and Circulation in NEET.
How many questions come from Body Fluids and Circulation in NEET?
Body Fluids and Circulation (Zoology, Class 11) has been asked 15 times in the 7 NEET papers from 2018, 2020, 2021, 2023, 2024, 2025 and 2026: about 2.1 questions a paper, 5% of all Zoology questions. It is the 10th most-asked of 15 Zoology chapters. NEET 2026 had 3 from it.
Which topics of Body Fluids and Circulation are asked most in NEET?
Blood composition (6), Cardiac cycle (5), ECG (3), Circulatory disorders (1), counted over the papers from 2018–2026.
Is Body Fluids and Circulation important for NEET 2027?
It is in the syllabus in force, so it can be asked. By past papers it ranks 10 of 15 in Zoology; use that to decide how much time it gets, not whether to study it.
Where can I solve Body Fluids and Circulation NEET previous year questions?
On Nikaalle, free: sign up and practise every past NEET question from Body Fluids and Circulation with an explanation for each, or sit the full papers timed. The ten questions on this page are our own, written in the same pattern.
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