Which of the following statements with reference to 'blood' is/are correct ?
1. Blood is composed of plasma and different types of cells.
2. The presence of haemoglobin makes blood appear red.
Select

Question

Which of the following statements with reference to 'blood' is/are correct ?
1. Blood is composed of plasma and different types of cells.
2. The presence of haemoglobin makes blood appear red.
Select the correct answer from the code given below :
Code :

UnlockIAS · Accepted Answer

Correct — B, Both 1 and 2. Statement 1 is right: blood is a fluid connective tissue made of a straw-coloured liquid matrix called plasma, which is roughly 55 per cent of the volume and about nine-tenths water, in which three kinds of formed elements are suspended — red blood cells or erythrocytes, white blood cells or leucocytes, and platelets. So blood is indeed plasma plus different types of cells. Statement 2 is also right: the colour comes from haemoglobin, the iron-containing pigment packed inside red blood cells. Each haem group holds an iron atom that binds oxygen, and it is this haem-iron that absorbs light in a way that makes oxygenated blood bright scarlet and deoxygenated blood a darker, duller red.

Why the other options are wrong — (a) This denies statement 1, but plasma plus formed elements is the standard description of blood in every textbook. A candidate might hesitate over the fact that platelets are strictly fragments of larger cells rather than complete cells; that technicality does not overturn the statement, which is about blood being a mixture of a liquid and cellular components.  (c) Both statements are correct, so this rules out the answer altogether. It is the option for a candidate who over-thinks both clauses at once.  (d) This denies statement 2, but haemoglobin is precisely what makes blood red. The proof runs the other way too: animals whose circulating fluid lacks haemoglobin are not red — a cockroach's haemolymph carries no respiratory pigment at all and looks colourless, while many molluscs and arthropods use the copper-based haemocyanin and have bluish blood.

Concept: Blood is classed as a fluid connective tissue: unlike other tissues its matrix is liquid. Plasma, about 55 per cent of blood by volume, is roughly 90 to 92 per cent water and carries proteins such as albumin, globulins and fibrinogen, along with glucose, salts, hormones and wastes. The remaining 45 per cent, the packed cell volume or haematocrit, consists of erythrocytes, leucocytes and platelets. Erythrocytes are the most numerous by far, and in adult humans they are biconcave discs that have lost their nucleus, which leaves the maximum room for haemoglobin — an iron-containing protein of four polypeptide chains, each carrying a haem group.

State PCS 2025 Q50 — Science & Technology PYQ with Answer

State PCS 2025 Q50 — Science & Technology PYQ with Answer