Question

Read the following statement and select the correct option.
Statement 1 : When the urine moves through the descending limb, it becomes hypertonic to blood plasma and as it passes through are ascending limb, of Henle's loop it becomes hypotonic to blood plasma.
Statement 2 : The descending limb is permeable to sodium ions, while the ascending limb is impermeable to sodium ions.

• A. Both statements 1 and 2 are correct and statement 2 is the correct explanation of statement 1.
• B. Both statements 1 and 2 are correct but statement 2 is not the correct explanation of statement 1
• C. Statement 1 is correct but statement 2 is incorrect.
• D. Both statement 1 and 2 are incorrect.

Answer 1

The correct option is C Statement 1 is correct but statement 2 is incorrect.

Descending limb of the loop of Henley is permeable to water but, is impermeable to electrolytes. So urine concentrates as it moves down. Ascending limb is impermeable to water but, it allows the transport of electrolytes actively, so it makes the urine hypotonic to blood plasma.

Thus, the correct answer is 'Statement 1 is correct but statement 2 is incorrect.'