Assertion: Like animal cells, sodium ions play the primary role in basic transport processes in plant cells.
Reason: In plant cells, the membrane potential is established mainly through pumping of sodium ions by sodium-potassium pumps.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

How many of the following processes involve active transport across membranes in plants?
I. the movement of mineral nutrients from the apoplast to the symplast.
II. the movement of sugar from mesophyll cells into sieve-tube members in maize.
III. the movement of sugar from one sieve-tube member to the next.
IV. K⁺ uptake by guard cells during stomatal opening.
V. the movement of mineral nutrients into cells of the root cortex.
1. 2
2. 3
3. 4
4. 5