Making urine concentrated — practice questions

Question 1 · difficulty L1 · recall

The ascending limb is relatively impermeable to:

• A. water
• B. all ions
• C. urea always
• D. sodium and chloride

Question 2 · difficulty L1 · recall

The descending limb is relatively permeable to:

• A. glucose by active transport only
• B. sodium chloride only but not water
• C. proteins
• D. water

Question 3 · difficulty L1 · recall

The nephron structure that establishes a counter-current gradient together with vasa recta:

• A. loop of Henle
• B. glomerulus only
• C. Bowman capsule
• D. urethra

Question 4 · difficulty L1 · recall

What is the basic mechanism involving the loop of Henle and vasa recta that helps concentrate urine?

• A. Simple filtration only
• B. Counter-current mechanism
• C. Cardiac conduction
• D. Portal circulation

Question 5 · difficulty L2 · understanding

Why is the medullary interstitium of the kidney highly osmotic?

• A. Plasma proteins are filtered into the medulla
• B. Glucose is stored there as glycogen
• C. Sodium chloride and urea accumulate in the medulla
• D. Oxygen is actively secreted into the tubule

Question 6 · difficulty L2 · understanding

What is the role of the vasa recta in urine concentration?

• A. It stores concentrated urine
• B. It produces filtrate directly inside Bowman's capsule
• C. It secretes ADH into the collecting duct
• D. It acts as a counter-current exchanger that helps preserve the medullary osmotic gradient

Question 7 · difficulty L3 · application

Why do juxtamedullary nephrons contribute strongly to the production of concentrated urine?

• A. Their long loops of Henle extend deep into the hyperosmotic medulla
• B. They lack glomeruli
• C. Their Bowman's capsules secrete ADH
• D. They empty directly into the renal artery

Question 8 · difficulty L3 · application

Water is removed from a collecting duct as it passes through a hyperosmotic medulla. What must also be true for substantial water reabsorption to occur?

• A. The collecting duct must be impermeable to water
• B. The collecting duct must be sufficiently permeable to water
• C. The glomerulus must stop filtering
• D. The renal pelvis must actively pump water

Question 9 · difficulty L3 · understanding

Given below are two statements: Statements I: Concentrated urine is formed due to counter current mechanism in nephron. Statement II: Counter current mechanism helps to maintain osmotic gradient in the medullary interstitium. In the light of the above statements, choose the most appropriate answer from the options given below.

• A. Statement I is correct but Statement II is incorrect.
• B. Statement I is incorrect but Statement II is correct.
• C. Both Statement I and Statement II are correct.
• D. Both Statement I and Statement II are incorrect.

Question 10 · difficulty L3 · understanding

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R) Assertion (A) : Ascending limb of loop of Henle is impermeable to water and allows transport of electrolytes actively or passively. Reason (R) : Dilution of filtrate takes place due to efflux of electrolytes in the medullary fluid. In the light of the above statements, choose the correct answer from the options given below :

• A. (A) is true but (R) is false
• B. (A) is false but (R) is true
• C. Both (A) and (R) are true and (R) is the correct explanation of (A)
• D. Both (A) and (R) are true and (R) is not the correct explanation of (A)