Question

Assertion :Renal threshold of glucose is said to be 180 mg per 100 ml.
Reason: Glucose starts appearing in the urine when its blood level exceed 180 mg per 100 ml of blood

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

Renal threshold of a substance is its highest concentration in the blood, upto which it is totally reabsorbed from the glomerular filtrate. Renal threshold

of glucose is about 180 mg per 100 ml. It is totally reabsorbed and does not appear in the urine so long as its blood level does not exceed 180 mg. But when its blood level exceeds 180 mg, some of the filtered glucose is left unabsorbed in the tubules and consequently appears in the urine. Some substances which are either totally reabsorbed actively or most of their amounts are reabsorbed actively are called high threshold substances. High threshold substances are excreted in the urine only when their blood concentration is considerably high, for example glucose and amino acids.

So, the correct answer is 'Both Assertion and Reason are correct and Reason is the correct explanation for Assertion'.