Body Fluids and Circulation is a Class 11 Zoology chapter in the NEET (UG) syllabus. NEET720 has 1,264 reviewed practice questions on it, each with a quick answer and a step-by-step explanation. The 8 questions below are free and fixed, so you can bookmark this page; the full chapter, plus mistake tracking and spaced revision, is in the app.
206
easy
846
medium
212
hard
Topics covered
Blood · Lymph and Tissue Fluid · Human Heart and Cardiac Cycle · ECG and Double Circulation · Regulation of Cardiac Activity and Disorders · Comparative Circulatory Systems · Blood Disorders · Electrocardiogram · Electrocardiograph (ECG) · Coagulation · Lymph · Circulatory patterns · Disorders · Disorders of Circulatory System · Special circulations · Integrated concepts · Nodal tissue · Regulation of cardiac activity · Numerical - Blood pressure · Numerical - Hardy-Weinberg (blood groups) · Numerical - Cardiac output · Numerical - Blood composition · Numerical - Cardiac cycle · Cardiovascular disorders · Human Lymphatic System · Human Circulatory Pathways · Human Heart · Heart Disorders · Blood Clotting · Blood Composition · Heart Structure · Composition of Blood · ECG and Blood Pressure · Circulatory Pathways · Blood cells · Cardiac conduction system · Comparative circulation · Heart Anatomy · Regulation of Circulation · Cardiac Cycle
8 free Body Fluids and Circulation practice questions with answers
Choose an answer in your head before opening it. Each explanation says why the correct option is right and, where relevant, why the tempting wrong option is wrong.
Question 1 · easy · Blood
Plasma, the straw-coloured viscous fluid component of blood, constitutes approximately what percentage of total blood volume?
- C.55%
- D.70%
- A.45%
- B.90%
Show answer and explanation
Answer: C. 55%
Plasma makes up nearly 55% of blood volume, with the remaining ~45% being formed elements (RBCs, WBCs, platelets).
Blood is a fluid connective tissue with two components: plasma (~55% by volume) and formed elements (~45%). Plasma itself is 90-92% water and 6-8% proteins, plus small amounts of minerals, glucose, amino acids and lipids in transit. Option C reflects the formed-elements share, a common mix-up; option D confuses plasma's own water content with its share of whole blood.
Common mistake: Confusing plasma's percentage of blood with plasma's internal water percentage (90-92%).
Key point: Plasma ≈ 55% of blood volume; formed elements ≈ 45% (this ratio is the basis of haematocrit).
Question 2 · easy · Blood
Which plasma protein is primarily responsible for maintaining the osmotic balance of blood?
- D.Fibrinogen
- A.Albumin
- B.Globulin
- C.Haemoglobin
Show answer and explanation
Answer: A. Albumin
Albumins are the most abundant plasma proteins and mainly help maintain the osmotic balance of blood.
Plasma proteins include fibrinogen (clotting), globulins (defence mechanisms/antibodies) and albumins (osmotic balance). Albumin's high concentration and molecular size make it the chief contributor to plasma colloid osmotic pressure, which keeps water within blood vessels. Haemoglobin is not a plasma protein at all — it is packaged inside RBCs.
Common mistake: Treating haemoglobin as a dissolved plasma protein rather than an intracellular RBC pigment.
Key point: Fibrinogen → clotting; Globulin → defence/antibodies; Albumin → osmotic balance.
Question 3 · medium · Blood
The average life span of a human erythrocyte, after which it is destroyed in the spleen, is about:
- A.60 days
- B.12 days
- C.120 days
- D.365 days
Show answer and explanation
Answer: C. 120 days
Human RBCs live for about 120 days, after which aged/damaged cells are destroyed in the spleen.
Erythrocytes, being biconcave and anucleate in mammals, cannot repair themselves indefinitely and are removed from circulation after roughly 120 days by macrophages in the spleen — hence the spleen's nickname 'graveyard of RBCs'. Platelets, by contrast, survive only about 5-9 days, a common source of confusion with option B.
Common mistake: Mixing up RBC life span (120 days) with platelet life span (5-9 days).
Key point: RBC life span ≈ 120 days; destroyed in spleen, the 'graveyard of RBCs'.
Question 4 · medium · Blood
In a healthy adult human, erythrocytes are normally formed in the:
- D.Red bone marrow
- A.Yellow bone marrow
- B.Liver
- C.Spleen
Show answer and explanation
Answer: D. Red bone marrow
In adults, RBCs are formed in the red bone marrow, while the spleen destroys aged RBCs.
Red bone marrow (found in flat bones like sternum, ribs, and vertebrae in adults) is the active site of erythropoiesis. The liver and spleen are important haematopoietic sites during foetal life but not normally in healthy adults. The spleen's adult role for RBCs is destruction of aged cells, not production, a point NEET frequently tests as a distractor pairing.
Common mistake: Assigning RBC production to the spleen instead of destruction.
Key point: Adult RBC formation: red bone marrow. Adult RBC destruction: spleen.
Question 5 · medium · Blood
Which is the most abundant type of leucocyte in normal human blood?
- D.Lymphocytes
- A.Neutrophils
- B.Monocytes
- C.Eosinophils
Show answer and explanation
Answer: A. Neutrophils
Neutrophils are the most abundant WBCs, forming the largest fraction of the total leucocyte count and acting as phagocytes against pathogens.
Among granulocytes, neutrophils vastly outnumber eosinophils and basophils, making them the single most abundant leucocyte type overall. They are phagocytic, engulfing bacteria and other pathogens by phagocytosis. Lymphocytes are the second most abundant and are central to immune responses (B and T types), but they do not exceed neutrophils in normal differential counts.
Common mistake: Assuming lymphocytes are most abundant because of their central immunological importance.
Key point: Abundance order (high to low): Neutrophils > Lymphocytes > Monocytes > Eosinophils > Basophils.
Question 6 · medium · Blood
Platelets (thrombocytes) are cell fragments produced in the bone marrow from large cells called:
- A.Erythroblasts
- B.Osteoblasts
- C.Megakaryocytes
- D.Monocytes
Show answer and explanation
Answer: C. Megakaryocytes
Platelets are small cell fragments pinched off from large bone-marrow cells called megakaryocytes.
Megakaryocytes are large, multinucleated bone-marrow cells whose cytoplasm fragments into thousands of platelets. Platelets play a crucial role in blood clotting/coagulation by releasing substances at the site of injury. Erythroblasts are RBC precursors, not platelet precursors, while osteoblasts are unrelated bone-forming cells of a different lineage entirely.
Common mistake: Confusing megakaryocytes with erythroblasts as the platelet source.
Key point: Platelets originate from megakaryocytes in the bone marrow, not from erythroid precursors.
Question 7 · easy · Blood
Which of the following is present in blood plasma only in small amounts, as a dissolved mineral ion, rather than as a major protein component?
- D.Na+
- A.Fibrinogen
- B.Globulin
- C.Albumin
Show answer and explanation
Answer: D. Na+
Plasma contains small amounts of minerals such as Na+, Ca2+, Mg2+, HCO3- and Cl-, distinct from its major protein fraction.
Besides water (90-92%) and proteins (6-8%: fibrinogen, globulins, albumins), plasma carries small quantities of mineral ions like Na+, Ca2+, Mg2+, HCO3- and Cl-, as well as glucose, amino acids and lipids that are always in transit. Fibrinogen, globulin and albumin are the three major plasma proteins, not trace minerals.
Common mistake: Lumping plasma proteins and plasma minerals together as one category.
Key point: Plasma minerals (Na+, Ca2+, Mg2+, HCO3-, Cl-) are present in small amounts, separate from the 6-8% protein fraction.
Question 8 · easy · Blood
The biconcave shape of a mature mammalian RBC primarily helps it by:
- A.Increasing surface area for efficient gas exchange
- B.Allowing the cell to divide rapidly
- C.Enabling active phagocytosis of pathogens
- D.Providing a nucleus for protein synthesis
Show answer and explanation
Answer: A. Increasing surface area for efficient gas exchange
The biconcave, anucleate shape of RBCs increases surface-area-to-volume ratio, aiding efficient O2/CO2 exchange and easy passage through capillaries.
Mammalian RBCs lack a nucleus at maturity and are biconcave discs, a shape that maximises surface area relative to volume, enhances flexibility for squeezing through narrow capillaries, and speeds gas diffusion across the membrane. RBCs do not divide (they are anucleate) and are not phagocytic — those are separate, mutually exclusive cell functions in blood.
Common mistake: Assuming a mature circulating RBC still possesses a nucleus and can divide.
Key point: Biconcave, anucleate shape of RBC → larger surface area → efficient O2 transport, not division or phagocytosis.
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Questions about Body Fluids and Circulation for NEET
How many NEET questions does NEET720 have on Body Fluids and Circulation?＋
NEET720 has 1,264 reviewed practice questions on Body Fluids and Circulation (Zoology): 206 easy, 846 medium and 212 hard. 8 of them are free on this page with full explanations; the rest are available in the app.
Is Body Fluids and Circulation a Class 11 or Class 12 chapter for NEET?＋
Body Fluids and Circulation is a Class 11 Zoology chapter in the NEET (UG) syllabus. Read the NCERT chapter first, then practise chapter-wise MCQs and previous-year questions.
How should I practise Body Fluids and Circulation for NEET?＋
Attempt the questions below without looking at the options for more than a few seconds, mark your answer, then read the explanation even when you were right. Record every mistake and revisit it after a gap. On NEET720 this happens automatically: wrong answers go to your Mistake Book and are scheduled for spaced revision.
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Questions are original NEET720 compositions reviewed for correctness, syllabus fit and option quality. Counts update as the bank grows (1,264 active practice questions in this chapter today).