Question

Assertion (A): Auxins promote the elongation of cells.

Reason (R): Auxins stimulate cell division in the short apical meristem.

Options

• Both A and R are true and R is the correct explanation of A.

• Both A and R are true but R is not the correct explanation of A.

• A is true but R is false.

• A is false but R is true.

Answer 1

Both A and R are true but R is not the correct explanation of A.

Explanation:

The assertion is true because auxins primarily promote cell elongation by increasing cell wall plasticity (the acid growth hypothesis), allowing cells to expand. The reason is also true because auxins are synthesised in the shoot apical meristem, where they actively stimulate cell division alongside cytokinins. However, the reason is not the correct explanation of the assertion, as a hormone’s ability to stimulate cell division in the meristem is a separate process that does not clarify the specific physiological mechanism behind how it causes individual cell elongation.