The blood from the glomerulus is carried away by:

1. Afferent arteriole

2. Efferent arteriole

3. Peritubular capillary network

4. Renal vein

Vasa recta in cortical nephrons :

1. Arises from afferent arteriole rather than efferent arteriole

2. Does not get involved in counter current exchange with loop of Henle

3. Carries deoxygenated blood rich in urea

4. Is absent or highly reduced 

The proximal convoluted tubule is lined by the:
1. Simple cuboidal epithelium
2. Simple columnar epithelium
3. Simple cuboidal brush bordered epithelium
4. Simple columnar brush bordered epithelium

During the concentration of urine by the human kidneys, NaCl is returned to the medullary interstitium by the:

1. Descending limb of the loop of Henle

2. Ascending limb of the loop of Henle

3. Descending limb of the vasa recta

4. Ascending limb of the vasa recta

An increase in the blood flow to the atria of the heart can cause the release of:

1. Erythropoeitin

2. Atrial natriuretic factor

3. Renin

4. Aldosterone

Identify the correct statement regarding the excretion of acids by the human kidney :
1. The filtered bicarbonate is absorbed by anion transport
2. The intercalated cells of the distal tubule secrete hydrogen ions to reabsorb bicarbonate from the tubular fluid.
3. All of the filtered bicarbonate is normally reabsorbed in the first half of the distal tubule.
4. Urine pH is normally greater than that of plasma.

Blood doping means use of banned substances by athletes that have a favorable effect on erythrocyte count by stimulating the bone marrow. The source of such a hormone can be the human:

1. Spleen

2. Heart 

3. Kidney

4. Lungs

The main disadvantage of urea as an excretory product for animals eliminating it would be:

1. its high toxicity

2. Needs lot of water to be eliminated

3. It being an osmolyte

4. Energy expenditure to produce it

Match each item in Column I with one in Column II and choose the correct option from the codes given below:

            A      B      C

 1.        b      d      f

 2.        a      d      f

 3.        a      c      e

 4.        b      d      e

Excretion of dilute urine requires