Blood is a fluid connective tissue made of two parts: plasma, the liquid matrix that is about 55 per cent of blood, and formed elements (RBCs, WBCs and platelets) that are about 45 per cent of blood. In plasma, 90-92 per cent is water and 6-8 per cent is proteins. Memory hook: "55 liquid, 45 cells" and inside plasma remember "90 water, 8 protein" so you never mix up the two ratios in the NEET exam.
Blood splits into plasma (55%) and formed elements (45%); inside plasma, water is 90-92% and proteins are 6-8% — keep the two ratios separate for NEET.
Your doubts, answered
Is plasma 55% of blood or is it the formed elements?
Plasma is the liquid matrix and forms nearly 55 per cent of blood. The formed elements (RBCs, WBCs, platelets) make up the remaining nearly 45 per cent. A quick check: the liquid part is always the larger share (55%), and the cells settle to the smaller share (45%). Students often flip these two, so lock 55 to plasma.
What is the difference between plasma composition and blood composition?
These are two different ratios and NEET mixes them up on purpose. Blood as a whole = plasma (55%) + formed elements (45%). Inside plasma alone, water is 90-92% and proteins are 6-8%. So 90-92% water is a fact about plasma, not about whole blood. Read the question carefully to see which ratio it wants.
How much of plasma is water and how much is protein?
90-92 per cent of plasma is water and proteins contribute 6-8 per cent of plasma. The remaining small part is minerals, glucose, amino acids, lipids, hormones and gases. The three major plasma proteins are fibrinogen, globulins and albumins.
What are the formed elements of blood?
Formed elements are the cells and cell fragments in blood: erythrocytes (RBCs), leucocytes (WBCs) and platelets (thrombocytes). Together they are about 45 per cent of blood. RBCs are the most abundant, a healthy adult man has about 5 to 5.5 million RBCs per cubic millimetre of blood.
Is serum the same as plasma?
No. Plasma is blood without the cells but WITH clotting factors like fibrinogen. Serum is plasma WITHOUT the clotting factors (they are used up during clotting). So serum = plasma minus fibrinogen and other clotting factors. This exact point was a NEET 2016 question.
⚠️ The NEET trap ✗ Thinking water is 90-92% of blood, or that plasma is 45% of blood. ✓ Plasma is 55% of BLOOD and formed elements are 45% of BLOOD. Water is 90-92% of PLASMA (not of blood) and proteins are 6-8% of PLASMA. Two separate ratios, two separate wholes. 🧠 55 vs 45 vs 90 vs 8 — which ratio belongs to what?
Real NEET questions
2018
Match the items given in Column I with those in Column II and select the correct option. Column I: a. Fibrinogen b. Globulin c. Albumin. Column II: (i) Osmotic balance (ii) Blood clotting (iii) Defence mechanism.
A · a-(i), b-(iii), c-(ii)
B · a-(i), b-(ii), c-(iii)
C · a-(iii), b-(ii), c-(i)
D · a-(ii), b-(iii), c-(i) ✓
Solution: Among the major plasma proteins: fibrinogen is needed for clotting/coagulation of blood (ii), globulins take part in the body's defence mechanism (iii), and albumins maintain osmotic balance (i). So a-(ii), b-(iii), c-(i).
2016
Serum differs from blood in
A · Lacking globulins
B · Lacking albumins
C · Lacking clotting factors ✓
D · Lacking antibodies
Solution: Plasma contains clotting factors in an inactive form. When these clotting factors are removed (used up during clotting), the remaining fluid is called serum. So serum differs from blood/plasma by lacking clotting factors.
Solved Body Fluids and Circulation NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
