Question 1

The straw-coloured, fluid matrix of blood (about 55% of blood volume) is called:

Accepted Answer

Plasma. Plasma is the liquid part of blood (~55%); serum is plasma without clotting factors.

Question 2

The most abundant plasma protein, responsible for maintaining osmotic balance, is:

Accepted Answer

Albumin. Albumins maintain the osmotic (oncotic) pressure; globulins are for defence and fibrinogen for clotting.

Question 3

The most abundant blood cells, which carry oxygen and lack a nucleus in humans, are the:

Accepted Answer

Erythrocytes (RBCs). RBCs (~5 million/mm³) are enucleate, biconcave and packed with haemoglobin for O₂ transport.

Question 4

A person with blood group AB is called a universal ______ because:

Accepted Answer

Recipient; plasma has no anti-A or anti-B antibodies. AB individuals lack anti-A/anti-B antibodies, so can receive any ABO type — universal recipients.

Question 5

The human heart is ______ chambered, with two atria and two ventricles:

Accepted Answer

Four. The human heart has four chambers — two atria (upper) and two ventricles (lower).

Question 6

The pacemaker of the heart, which initiates the heartbeat, is the:

Accepted Answer

Sino-atrial node (SAN). The SA node in the right atrium sets the rhythm — hence "pacemaker".

Question 7

The volume of blood pumped out by one ventricle in one heartbeat is the:

Accepted Answer

Stroke volume. Stroke volume (~70 mL) is the blood ejected per beat by a ventricle.

Question 8

In an ECG, the ______ wave represents the depolarisation of the ventricles:

Accepted Answer

QRS complex. The QRS complex marks ventricular depolarisation (leading to contraction).

Question 9

Persistently high blood pressure (e.g. above 140/90 mmHg) is called:

Accepted Answer

Hypertension. Hypertension is high blood pressure (normal ≈ 120/80 mmHg), a major risk factor for heart disease.

Question 10

Chest pain due to insufficient oxygen reaching the heart muscle is called:

Accepted Answer

Angina (pectoris). Angina pectoris is acute chest pain from inadequate oxygen supply to the myocardium.

Question 11

Plasma proteins account for nearly 7% of plasma by weight. If all clotting factors including fibrinogen were removed while the cells stayed intact, the remaining fluid would be best described as:

Accepted Answer

Blood minus fibrinogen but still containing formed elements — not a standard named fluid. Serum is the fluid left after clotting, i.e. plasma without fibrinogen and clotting factors — but serum also lacks the formed elements. Since the cells are still present here, it is simply defibrinated blood, not serum.

Question 12

A patient has severe liver damage that lowers albumin synthesis. The most direct physiological consequence of this fall in plasma albumin is:

Accepted Answer

Oedema due to reduced plasma osmotic (oncotic) pressure. Albumin is the chief plasma protein maintaining colloid osmotic pressure; its fall lets fluid leak into tissue spaces, causing oedema. It has no role in raising oxygen carriage or clotting.

Question 13

Which combination correctly pairs a plasma component with its major role?

Accepted Answer

Globulins → defence (antibodies); Fibrinogen → clotting; Albumin → osmotic balance. Globulins are primarily involved in body defence, fibrinogen is needed for clot formation, and albumin maintains the osmotic balance of blood — the standard NCERT pairing.

Question 14

Roughly 90–92% of plasma is water. Besides proteins, plasma also transports small amounts of which set of substances?

Accepted Answer

Glucose, amino acids, lipids, and mineral ions such as Na⁺, Ca²⁺, and HCO₃⁻. Plasma carries dissolved nutrients (glucose, amino acids, lipids) and ions (Na⁺, Ca²⁺, HCO₃⁻, etc.). Oxygen is mainly carried by RBC haemoglobin, and cells are formed elements, not dissolved solutes.

Question 15

An anucleate formed element that survives about 120 days and is destroyed mainly in the spleen and liver is the:

Accepted Answer

Erythrocyte (RBC). Mature mammalian RBCs lack a nucleus, live roughly 120 days, and are broken down in the spleen and liver. Platelets live only ~5–9 days and WBCs are nucleated.

Question 16

Which grouping of leucocytes into granulocytes and agranulocytes is entirely correct?

Accepted Answer

Granulocytes: neutrophils, eosinophils, basophils; Agranulocytes: lymphocytes, monocytes. Neutrophils, eosinophils, and basophils have cytoplasmic granules (granulocytes); lymphocytes and monocytes lack prominent granules (agranulocytes).

Question 17

A person with blood group O who is Rh negative can safely DONATE packed red cells to which of the following in an emergency?

Accepted Answer

A recipient of any ABO group who is Rh negative. O negative red cells carry neither A, B, nor Rh(D) antigens, so they can be given to recipients of any ABO group provided they are also Rh negative (or, for RBCs, to Rh positive recipients too). Restricting to only O negative is unnecessary for the cells.

Question 18

Normal counts in adult human blood are approximately:

Accepted Answer

RBC 5–5.5 million/mm³, WBC 6000–8000/mm³, platelets 1.5–3.5 lakh/mm³. Standard NCERT values are ~5–5.5 million RBC/mm³, 6000–8000 WBC/mm³, and 1.5–3.5 lakh platelets/mm³.

Question 19

Blood returning from the body tissues enters the human heart first at the:

Accepted Answer

Right atrium via the superior and inferior venae cavae. Deoxygenated systemic blood returns through the venae cavae into the right atrium. The pulmonary veins carry oxygenated blood into the left atrium.

Question 20

The correct sequence of the cardiac impulse-conducting pathway is:

Accepted Answer

SAN → AVN → bundle of His → bundle branches → Purkinje fibres. The impulse originates at the SAN (pacemaker), passes to the AVN, then along the bundle of His and its branches, and finally through the Purkinje fibres to the ventricular muscle.

Body Fluids and Circulation — NEET Biology MCQs with Solutions

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Sample questions with solutions