Select the correct answers to the questions from the given options. (Do not copy the questions, write the correct answer only.)
Assertion (A): Deficiency of Antidiuretic hormone causes an increase in urination. Reason (R): Antidiuretic hormone acts on the kidney to reabsorb water from the kidney tubules.
Topic: Assertion-Reason — antidiuretic hormone
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Pick an option and check your answer. The full worked answer is below either way.
Answer
(c) Both (A) and (R) are true.
BOTH STATEMENTS ARE TRUE, and the reason explains the assertion exactly.
ADH (vasopressin), from the posterior pituitary, makes the walls of the kidney tubules and collecting ducts permeable to water, so water is REABSORBED back into the blood and the urine becomes concentrated.
If ADH is deficient, that reabsorption fails. Water stays in the tubules and is lost, so the person passes large volumes of dilute urine — which is the disorder DIABETES INSIPIDUS.
The name of the hormone contains its own explanation: ANTI-DIURETIC means "against the production of urine". Take it away and urine production rises.
Note the ICSE convention on assertion-reason options in this paper: option (C) is simply "Both (A) and (R) are true", without the further split into whether (R) explains (A) that the 2026 paper uses. Read the options offered before assuming the four-way format.
Both (A) and (R) are true.