Excretory Products and their Elimination: NEET previous year questions

A fall in glomerular filtration rate/blood flow (Statement III) activates the juxta glomerular (JG) cells to release renin, which converts angiotensinogen to angiotensin I and then angiotensin II (Statement V). Angiotensin II acts as a vasoconstrictor and stimulates the adrenal cortex to release aldosterone (Statement IV). Aldosterone then promotes reabsorption of $\mathrm{Na}^{+}$ and water from the distal tubule (Statement II), which raises blood pressure and GFR (Statement I). Correct order: III, V, IV, II, I.

The juxtaglomerular apparatus forms at the point of contact where the distal convoluted tubule (macula densa) touches the afferent arteriole (juxtaglomerular cells) of the same nephron. Therefore the correct pairing is distal convoluted tubule and afferent renal arteriole, option (4).

NTA's paper said only that sodium and water are reabsorbed in Henle's loop; statement III is worded more precisely here, because the two happen in different limbs. As written, statement III is false: the ascending limb transports electrolytes but is impermeable to water. Statement I is true because the descending limb is permeable to water and nearly impermeable to electrolytes. Statement II is true because tubular fluid becomes concentrated while descending. Statement IV is true because electrolytes leave the ascending limb by active or passive transport. Thus statements I, II and IV are correct, so the answer is option (4). NCERT Class 11, Excretory Products and their Elimination (counter-current mechanism).

Glycosuria and ketonuria together indicate diabetes mellitus: excess blood glucose spills into urine and increased fat use produces urinary ketone bodies. Chapter: Excretory Products and their Elimination.

Aldosterone promotes the reabsorption of Na^+ and water from the renal tubules, reducing urine volume and preventing diuresis. Chapter: Excretory Products and their Elimination.