Assertion (A) An average adult have about 5-6 litres of blood by volume in his body.

Reason (R) The main functions of the blood in our body are transportation and protection.

1. Both A and R are true
2. Both A and R are false
3. A is true and R is false
4. A is false and R is true

Main reason for sharp rise in world human population in the recent past

1. Poor health care
2. Improved nutrition
3. More deaths
4. Small scale immunisation

Which of the following blood vessels is comprised of thick walls and narrow central lumen?

1. Vein
2. Venule
3. Artery
4. Capillary

Maximum amount of water from the glomerular filtrate is reabsorbed in

1. PCT
2. descending limbs of loop of Henle
3. ascending limbs of loop of Henle
4. DCT