Given below are two statements: Statement I: NaCl carried out by the ascending limb of Henle's loop is exchanged with the descending limb of the vasa recta. Statement II: The osmolarity of the interstitial fluid falls from about 1200 mOsmol L⁻¹ in the cortex to about 300 mOsmol L⁻¹ in the inner medulla. Choose the correct answer.

Statement I is correct but Statement II is incorrect

Both Statement I and Statement II are correct

Statement I is incorrect but Statement II is correct

Both Statement I and Statement II are incorrect

Excretory Products and their Elimination

10 NEET-UG practice questions on Excretory Products and their Elimination, part of Zoology. The first 10 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Easy
In haemodialysis, the dialysing fluid has the same composition as plasma except that it lacks
1. Aglucose
2. Bbicarbonate ions
3. Cnitrogenous wastes
4. Dsodium ions
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Answer: C · nitrogenous wastes
The dialysing fluid has the same composition as plasma except for nitrogenous wastes. The wastes therefore move out of the blood down their concentration gradient across the porous cellophane membrane, and the cleared blood is returned to the patient.
- A: Glucose is a plasma constituent, so it is not the missing component named in NCERT.
- B: Bicarbonate is a plasma constituent, so it is not the missing component named in NCERT.
- D: Sodium ions are kept in the fluid so that the patient does not lose them from the blood.
Remember this
The concentration gradient for nitrogenous wastes drives dialysis, because the fluid matches plasma in everything except those wastes.
Question 2 · Hard
Regarding the regulation of kidney function, consider the following: A. Excessive loss of fluid from the body can activate osmoreceptors, which stimulate the hypothalamus to release ADH. B. By constricting blood vessels, ADH can raise blood pressure and thereby the GFR. C. Aldosterone causes reabsorption of Na⁺ and water mainly from the proximal convoluted tubule. D. Atrial natriuretic factor causes vasodilation and acts as a check on the renin-angiotensin mechanism. Choose the correct answer.
1. AA, B and D only
2. BA and D only
3. CB, C and D only
4. DA, B and C only
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Answer: A · A, B and D only
A, B and D follow NCERT: osmoreceptors trigger ADH release, ADH has a constrictory effect that raises GFR, and ANF lowers blood pressure and opposes the renin-angiotensin mechanism. C is wrong because aldosterone acts on the distal parts of the tubule.
- B: This rejects B, overlooking the constrictory effect of ADH on blood vessels.
- C: This accepts C and rejects A, although osmoreceptors do trigger ADH release.
- D: This accepts C, which puts the action of aldosterone in the wrong part of the tubule.
Remember this
Aldosterone acts on the distal tubule parts; ANF is the check that opposes the renin-angiotensin mechanism.
Question 3 · Medium
A fall in glomerular blood pressure sets off a hormonal cascade. Which substance in this cascade both constricts blood vessels and activates the adrenal cortex to release aldosterone?
1. AAngiotensin II
2. BRenin
3. CAtrial natriuretic factor
4. DAngiotensin I
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Answer: A · Angiotensin II
JG cells release renin, which converts angiotensinogen to angiotensin I and then to angiotensin II. Angiotensin II is a powerful vasoconstrictor that raises glomerular blood pressure and GFR, and it also activates the adrenal cortex to release aldosterone.
- B: Renin starts the cascade by its action on angiotensinogen and does not itself act on the adrenal cortex.
- C: ANF causes vasodilation and acts as a check on this cascade.
- D: Angiotensin I is only the intermediate formed before angiotensin II.
Remember this
Angiotensin II raises GFR by vasoconstriction and raises reabsorption through aldosterone.
Question 4 · Medium
Given below are two statements: Statement I: NaCl carried out by the ascending limb of Henle's loop is exchanged with the descending limb of the vasa recta. Statement II: The osmolarity of the interstitial fluid falls from about 1200 mOsmol L⁻¹ in the cortex to about 300 mOsmol L⁻¹ in the inner medulla. Choose the correct answer.
1. ABoth Statement I and Statement II are correct
2. BStatement I is incorrect but Statement II is correct
3. CBoth Statement I and Statement II are incorrect
4. DStatement I is correct but Statement II is incorrect
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Answer: D · Statement I is correct but Statement II is incorrect
Statement I is the NCERT account of the counter-current exchange: NaCl from the ascending limb enters the descending vasa recta and is returned to the interstitium by the ascending vasa recta. Statement II reverses the gradient: osmolarity rises from about 300 mOsmol L⁻¹ in the cortex to about 1200 mOsmol L⁻¹ in the inner medulla.
- A: Statement II has the gradient upside down, so both cannot be correct.
- B: Statement I is correct and Statement II is the one that reverses the gradient.
- C: Statement I correctly describes the exchange between Henle's loop and the vasa recta.
Remember this
Medullary osmolarity rises inward from 300 to 1200 mOsmol L⁻¹, built by NaCl and urea.
Question 5 · Easy
A student compares sections of different nephron segments under a microscope. Which segment has a simple cuboidal brush border epithelium that enlarges the surface for reabsorption?
1. ACollecting duct
2. BProximal convoluted tubule
3. CBowman's capsule
4. DAscending limb of Henle's loop
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Answer: B · Proximal convoluted tubule
The proximal convoluted tubule is lined by simple cuboidal brush border epithelium, which increases the surface area for reabsorption. This is why nearly all essential nutrients and 70-80% of electrolytes and water are reabsorbed here.
- A: The collecting duct is a long duct that concentrates urine, and it is not the segment described by a brush border.
- C: Bowman's capsule is a double-walled cup around the glomerulus that receives the filtrate.
- D: Reabsorption in the ascending limb is minimum, and the brush border is a feature of the PCT.
Remember this
The PCT has the brush border and carries out the largest share of reabsorption in the nephron.
Question 6 · Easy
A healthy adult has a glomerular filtration rate of 125 mL per minute. What volume of filtrate do the kidneys form in 24 hours?
1. A18 L
2. B125 L
3. C7.5 L
4. D180 L
Answer and explanation in LearnFree account
Question 7 · Medium
Match List-I with List-II. List-I (nephron segment) A. Descending limb of Henle's loop B. Ascending limb of Henle's loop C. Proximal convoluted tubule D. Collecting duct List-II (feature) I. Reabsorbs large amounts of water and passes small amounts of urea into the medullary interstitium II. Reabsorbs nearly all essential nutrients and 70-80% of electrolytes and water III. Permeable to water but almost impermeable to electrolytes IV. Impermeable to water but allows transport of electrolytes
1. AA-III, B-IV, C-I, D-II
2. BA-IV, B-III, C-II, D-I
3. CA-III, B-IV, C-II, D-I
4. DA-IV, B-III, C-I, D-II
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Question 8 · Hard
A hypothetical drug stops electrolyte transport out of the ascending limb of Henle's loop, while every other segment works normally. Which early effect on urine is expected?
1. ASmaller volume of more concentrated urine, as the medullary gradient rises
2. BUnchanged volume and concentration, as ADH fully compensates for the block
3. CLarger volume of less concentrated urine, as the medullary gradient falls
4. DLarger volume with much glucose, as the PCT stops reabsorbing nutrients
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Question 9 · Medium
Given below are two statements about the pathway in the figure: Statement I: P is an enzyme released by the JG cells, and Q is angiotensin I. Statement II: R comes from the adrenal medulla and increases the loss of Na⁺ and water in urine. Choose the correct answer.
Figure: MedExams
1. ABoth Statement I and Statement II are incorrect
2. BStatement I is correct but Statement II is incorrect
3. CStatement I is incorrect but Statement II is correct
4. DBoth Statement I and Statement II are correct
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Question 10 · Medium
Osmolarity of the fluid is plotted along a human renal tubule, from Bowman's capsule to the collecting duct. Which marked segment is impermeable to water but allows electrolytes to leave the tubule?
Figure: MedExams
1. ASegment P
2. BSegment R
3. CSegment S
4. DSegment Q
Answer and explanation in LearnFree account

Excretory Products and their Elimination

In haemodialysis, the dialysing fluid has the same composition as plasma except that it lacks

A fall in glomerular blood pressure sets off a hormonal cascade. Which substance in this cascade both constricts blood vessels and activates the adrenal cortex to release aldosterone?

A student compares sections of different nephron segments under a microscope. Which segment has a simple cuboidal brush border epithelium that enlarges the surface for reabsorption?

A healthy adult has a glomerular filtration rate of 125 mL per minute. What volume of filtrate do the kidneys form in 24 hours?

A hypothetical drug stops electrolyte transport out of the ascending limb of Henle's loop, while every other segment works normally. Which early effect on urine is expected?

Given below are two statements about the pathway in the figure: Statement I: P is an enzyme released by the JG cells, and Q is angiotensin I. Statement II: R comes from the adrenal medulla and increases the loss of Na⁺ and water in urine. Choose the correct answer.

Osmolarity of the fluid is plotted along a human renal tubule, from Bowman's capsule to the collecting duct. Which marked segment is impermeable to water but allows electrolytes to leave the tubule?