Blood is a red, viscous connective tissue flowing within blood vessels. Which of the following statements are TRUE?
(A) The average volume in a healthy adult male and female is about 5 and 4.5 liters respectively.
(B) The plasma contains 70% water, 20% proteins, nutrients, salts, and hormones.
(C) The hemoglobin binds oxygen in the lungs to transport it throughout the body.
(D) The red blood corpuscles act as the body's defense mechanism against infections.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A), (C) and (D) only
Note: The given answer is as per the official NTA Answer Key. However, none of the given options appears to be correct, because statement (D) describes white blood corpuscles and not red blood corpuscles, as explained below.
Blood is a fluid connective tissue made of a liquid part, the plasma (about 55% of the volume), and the formed elements: red blood cells, which carry oxygen, white blood cells, which fight infection, and platelets, which help clotting.
(A) The average volume in a healthy adult male and female is about 5 and 4.5 liters respectively. Correct. An adult has roughly 5-6 litres of blood, and women, being on average smaller, have a little less, about 4-5 litres.
(B) The plasma contains 70% water, 20% proteins, nutrients, salts, and hormones. Incorrect. Plasma is about 90-92% water and only 6-8% proteins (albumin, globulins, fibrinogen); the rest is glucose, salts, hormones and other substances in small amounts.
(C) The hemoglobin binds oxygen in the lungs to transport it throughout the body. Correct. Haemoglobin, the iron-containing red pigment of red blood cells, picks up oxygen in the lungs as oxyhaemoglobin and releases it in the tissues.
(D) The red blood corpuscles act as the body’s defense mechanism against infections. Correct as per NTA; however, it is not correct as a statement about red blood corpuscles. The body’s defence against infection is the work of the white blood corpuscles (leucocytes), which engulf germs and make antibodies. Red blood corpuscles carry oxygen and carbon dioxide and have no role in defence.