Given below are two statements: Assertion [A]: Human body is incapable of digesting cellulose. Reason [R]: Starch degrading enzyme, diastase, is found in the human body. Choose the answer from the code given below: Codes

The correct answer is B. Both statements are true, but the reason does not explain the assertion.

• Assertion [A] is true. Humans lack cellulase, the enzyme that breaks the beta-1,4 glycosidic bonds in cellulose. So cellulose passes through the gut as dietary fibre. Ruminants and termites digest it only with the help of symbiotic microbes that make cellulase.
• Reason [R] is true. Salivary and pancreatic amylase (older texts call it diastase) hydrolyse the alpha-1,4 bonds in starch. That is a fact about a different substrate.
• Why [R] is not the explanation. The existence of amylase says nothing about why cellulose is not digested. The missing enzyme is the cause, so option A is wrong.
• Option C is wrong because [A] is true and [R] is also true. Option D is wrong because both statements are true.

The core concept is enzyme specificity: each enzyme acts on one bond type. This links to the Biology and nutrition part of the syllabus and to Mains questions on dietary fibre and gut health.

Trap: Aspirants assume that any true reason must explain the assertion. Check whether the reason actually causes the assertion.