What percentage of plasma is water?

✅ Correct Answer: C — 90-92%

Blood plasma is approximately 90-92% water. The remaining 8-10% consists of dissolved substances including: Proteins (albumin, globulin, fibrinogen), Hormones, Nutrients (glucose, amino acids, fatty acids), Electrolytes (sodium, potassium), Gases (CO2, O2), and Waste products (urea, creatinine). Plasma makes up about 55% of total blood volume.

❌ Why other options are wrong:

• A. 55% — 55% is actually the percentage of plasma in total blood volume (not water content in plasma).

• B. 70% — 70% is approximately the water content of the entire human body, not specifically plasma.

• D. 99% — 99% is close to the water content of some body fluids like saliva/urine, but not plasma.

📝 Important Note: Blood = Plasma (55%) + Formed elements (45% RBCs, WBCs, platelets). Plasma = 90-92% water + 8-10% proteins and other substances. Serum = Plasma without clotting factors. Fibrinogen in plasma helps in blood clotting. Important SSC CGL biology fact.