NEET Biology Excretory Products and Their Elimination MCQs Set 10

Answer: (b) Antennal glands - Planaria

Explanation:
1. Antennal glands are excretory organs of prawns (crustaceans); Planaria has flame cells (protonephridia).

Teacher's Note:
1. Nephron: Bowman's capsule and glomerulus (Malpighian body), PCT, loop of Henle, DCT and collecting duct; the loop of Henle dips into the medulla.
2. Glomerular filtration rate is about 125 mL per minute (180 litres per day), and 99 per cent of the filtrate is reabsorbed.

Answer: (d) Loop of Henle

Explanation:
1. The loop of Henle extends deep into the medulla, while the Malpighian body, PCT and DCT lie in the cortex.

Teacher's Note:
1. PCT reabsorbs nearly all nutrients, most electrolytes and water; DCT does conditional reabsorption of Na+ and water and secretes H+, K+ and NH3.
2. The countercurrent mechanism of the loop of Henle and vasa recta, with NaCl and urea, forms the medullary gradient for concentrated urine.

Answer: (d) Many bony fishes, aquatic amphibians, aquatic insects.

Explanation:
1. Many bony fishes, aquatic amphibians and aquatic insects are ammonotelic.

Teacher's Note:
1. Renin released by JG cells forms angiotensin II, which raises blood pressure and GFR and stimulates aldosterone release.
2. Ammonotelic animals excrete ammonia, ureotelic animals urea and uricotelic animals uric acid.

Answer: (d) Reabsorption of hydrogen and potassium ions occur in DCT.

Explanation:
1. Hydrogen and potassium ions are secreted, not reabsorbed, in the DCT.

Teacher's Note:
1. Nephron: Bowman's capsule and glomerulus (Malpighian body), PCT, loop of Henle, DCT and collecting duct; the loop of Henle dips into the medulla.
2. Glomerular filtration rate is about 125 mL per minute (180 litres per day), and 99 per cent of the filtrate is reabsorbed.

Answer: (b) DCT

Explanation:
1. The DCT carries out conditional reabsorption of Na+ and water.

Teacher's Note:
1. PCT reabsorbs nearly all nutrients, most electrolytes and water; DCT does conditional reabsorption of Na+ and water and secretes H+, K+ and NH3.
2. The countercurrent mechanism of the loop of Henle and vasa recta, with NaCl and urea, forms the medullary gradient for concentrated urine.

Answer: (c) Collecting duct

Explanation:
1. The collecting duct allows passage of a small amount of urea into the medullary interstitium to maintain the osmotic gradient.

Teacher's Note:
1. Renin released by JG cells forms angiotensin II, which raises blood pressure and GFR and stimulates aldosterone release.
2. Ammonotelic animals excrete ammonia, ureotelic animals urea and uricotelic animals uric acid.

Answer: (c) A-(ii), B-(iv), C-(i), D-(iii)

Explanation:
1. Glycosuria is glucose in urine, ketonuria is ketone bodies in urine, glomerulonephritis is inflammation of the glomeruli and uremia is excess urea in the blood.

Teacher's Note:
1. Nephron: Bowman's capsule and glomerulus (Malpighian body), PCT, loop of Henle, DCT and collecting duct; the loop of Henle dips into the medulla.
2. Glomerular filtration rate is about 125 mL per minute (180 litres per day), and 99 per cent of the filtrate is reabsorbed.

Answer: (b) A fall in glomerular blood flow can activate the JG cells to release renin.

Explanation:
1. A fall in glomerular blood flow activates the JG cells to release renin; the other statements are wrong.

Teacher's Note:
1. PCT reabsorbs nearly all nutrients, most electrolytes and water; DCT does conditional reabsorption of Na+ and water and secretes H+, K+ and NH3.
2. The countercurrent mechanism of the loop of Henle and vasa recta, with NaCl and urea, forms the medullary gradient for concentrated urine.

Answer: (a) PCT, DCT

Explanation:
1. Bicarbonate is reabsorbed in the PCT, and the DCT is also capable of reabsorbing it.

Teacher's Note:
1. Renin released by JG cells forms angiotensin II, which raises blood pressure and GFR and stimulates aldosterone release.
2. Ammonotelic animals excrete ammonia, ureotelic animals urea and uricotelic animals uric acid.

Answer: (b) Glucose, Na+

Explanation:
1. Glucose and Na+ are reabsorbed actively; water is reabsorbed passively.

Teacher's Note:
1. Nephron: Bowman's capsule and glomerulus (Malpighian body), PCT, loop of Henle, DCT and collecting duct; the loop of Henle dips into the medulla.
2. Glomerular filtration rate is about 125 mL per minute (180 litres per day), and 99 per cent of the filtrate is reabsorbed.

Answer: (c) relaxation of the urethral sphincter

Explanation:
1. During micturition the bladder muscle contracts and the urethral sphincter relaxes, allowing urine to be voided.

Teacher's Note:
1. PCT reabsorbs nearly all nutrients, most electrolytes and water; DCT does conditional reabsorption of Na+ and water and secretes H+, K+ and NH3.
2. The countercurrent mechanism of the loop of Henle and vasa recta, with NaCl and urea, forms the medullary gradient for concentrated urine.

Answer: (b) a, d, e

Explanation:
1. Angiotensin II is a vasoconstrictor that raises glomerular pressure and GFR and stimulates aldosterone release; it does not release renin, so a, d and e are wrong.

Teacher's Note:
1. Renin released by JG cells forms angiotensin II, which raises blood pressure and GFR and stimulates aldosterone release.
2. Ammonotelic animals excrete ammonia, ureotelic animals urea and uricotelic animals uric acid.

Answer: (c) Descending limb of Henle's loop

Explanation:
1. The descending limb of the loop of Henle is permeable to water but almost impermeable to electrolytes.

Teacher's Note:
1. Nephron: Bowman's capsule and glomerulus (Malpighian body), PCT, loop of Henle, DCT and collecting duct; the loop of Henle dips into the medulla.
2. Glomerular filtration rate is about 125 mL per minute (180 litres per day), and 99 per cent of the filtrate is reabsorbed.

Answer: (d) Ascending limb of Henle's loop

Explanation:
1. The ascending limb is impermeable to water, so water is not reabsorbed there.

Teacher's Note:
1. PCT reabsorbs nearly all nutrients, most electrolytes and water; DCT does conditional reabsorption of Na+ and water and secretes H+, K+ and NH3.
2. The countercurrent mechanism of the loop of Henle and vasa recta, with NaCl and urea, forms the medullary gradient for concentrated urine.

Answer: (c) Human kidneys can produce only hypertonic urine nearly five times concentrated than the initial filtrate.

Explanation:
1. Human kidneys can produce urine about four times more concentrated than the initial filtrate (1200 mOsm/L against 300 mOsm/L), not five times.

Teacher's Note:
1. Renin released by JG cells forms angiotensin II, which raises blood pressure and GFR and stimulates aldosterone release.
2. Ammonotelic animals excrete ammonia, ureotelic animals urea and uricotelic animals uric acid.

Answer: (b) NaCl and Urea

Explanation:
1. NaCl and urea produce the increasing osmolarity from cortex to inner medulla.

Teacher's Note:
1. Nephron: Bowman's capsule and glomerulus (Malpighian body), PCT, loop of Henle, DCT and collecting duct; the loop of Henle dips into the medulla.
2. Glomerular filtration rate is about 125 mL per minute (180 litres per day), and 99 per cent of the filtrate is reabsorbed.

Answer: (d) Urea

Explanation:
1. H+, ammonia and creatinine are secreted in the PCT, whereas urea is not actively secreted there.

Teacher's Note:
1. PCT reabsorbs nearly all nutrients, most electrolytes and water; DCT does conditional reabsorption of Na+ and water and secretes H+, K+ and NH3.
2. The countercurrent mechanism of the loop of Henle and vasa recta, with NaCl and urea, forms the medullary gradient for concentrated urine.

Answer: (b) Henle's loop and Vasa recta

Explanation:
1. The loop of Henle and the vasa recta maintain the medullary gradient needed to produce concentrated urine.

Teacher's Note:
1. Renin released by JG cells forms angiotensin II, which raises blood pressure and GFR and stimulates aldosterone release.
2. Ammonotelic animals excrete ammonia, ureotelic animals urea and uricotelic animals uric acid.

Answer: (d) Complete blood plasma is filtered in ultrafiltration process.

Explanation:
1. Only the plasma minus most proteins is filtered by ultrafiltration; blood cells and big proteins are retained.

Teacher's Note:
1. Nephron: Bowman's capsule and glomerulus (Malpighian body), PCT, loop of Henle, DCT and collecting duct; the loop of Henle dips into the medulla.
2. Glomerular filtration rate is about 125 mL per minute (180 litres per day), and 99 per cent of the filtrate is reabsorbed.