Assertion: Renal threshold of glucose is said to be 180 mg/100 mL
Reason: Glucose starts appearing in the urine when its blood level exceeds 180 mg/100 mL of blood

Options

A. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
B. If both the assertion and the reason are true and the reason is not a correct explanation of the assertion
C. If the assertion is true but the reason is false
D. If both the assertion and reason are false

Answer

A

Explanation

(a) 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 exceeds 180 mg , some of the filtered glucose is left unabsorbed in the tubules and consequently appears in the urine. Some substance which are either totally reabsorbed actively or most of their amounts are reabsorbed actively are called high threshold substance .High threshold substance are excreted in the urine only when their blood concentration is considerably high, for example glucose amino acid.