Which part of the nephrons is impermeable to water?
1. Proximal convoluted tubule
2. Distal convoluted tubule
3. Ascending limb of loop of Henle
4. Descending limb of loop of Henle

When kidney of a person is damaged, he/she invariably suffers fom anaemia because

(1) RBCs pass through the glomerulus

(2) Sufficient erythropoietin is not produced

(3) haemoglobin is not synthesised sufficiently

(4) Iron and viatmin B-12 are not able to bind to haemoglobin.

Which of the following process of urine formation takes place all along the renal tubule and collecting duct?

1. Ultrafiltration and tubular reabsorption

2. Ultrafiltration and tubular secretion

3. Tubular reabsorption and secretion

4. Anti-current mechanism and reabsorption

In man, in which part of the uriniferous tubule reabsorpton of glucose occurs?
(1) Collecting tube

(2) Henle's loop

(3) Distal convoluted tubule

(4) Proximal convoluted tubule

What is true of urea biosynthesis?

(1) Uric acid is starting point

(2) Urea is synthesised in lysosomes

(3) Urea cycle enzymes are located inside mitochondria

(4) Urea is synthesised in kidney

Assertion   :       Ammonia should be eliminated from the body as rapidly as it is formed.

Reason      :       Ammonia is insoluble in water.

Assertion   :       Urinary bladder and ureters are lined by transitional epithelium.

Reason      :       Ureters carry the urine to urinary bladder where it is stored temporarily.

Assertion   :       In vertebrates, the liver is also referred as an accessory excretory organ.

Reason      :       Liver helps kidneys in the secretion of urine.
1.  Both A & R are true and the R is the correct explanation of the A.
2.  Both A & R are true but the R is not the correct explanation of the A.
3.  A is true statement but R is false.
4.  Both A and R are false statements.

Assertion   :       Sharks are said to be ammonotelic animals.

Reason      :       Sharks can retain considerable amounts of ammonia in their blood.

Assertion   :       Aquatic mammals like whales and seals are said to be ureotelic animals.

Reason      :       It is because of the fact that their main nitrogenous waste product is urea.