Plants came on land before animals. All the following were evolutionary adaptations for terrestrial life except:
1. guard cells
2. ${\mathrm{C}}_3$ photosynthesis
3. rhizoids
4. vascular bundles

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

The molar concentration of a sugar solution in an open beaker has been determined to be 0.3M. The solution is kept at 27 degree Celsius. The solute potential will be about:
1. - 3.75
2. - 7.48
3. - 9.18
4. 0

Identify the incorrect statement regarding plasmolysis in plant cells:
1. If a plant cell is placed in a hypertonic solution, the plant cell loses water and hence turgor pressure by plasmolysis.
2. If cytorrhysis occurs the plant will wilt.
3. Plasmolysis can be reversed if the cell is placed in a hypotonic solution in many cases.
4. Convex plasmolysis is always reversible.

Water potential (Ψ) in plants is affected by:
I. mechanical pressure.
II. matrix effects (e.g., fluid cohesion and surface tension).
III. dissolved solutes.
IV. osmosis.
1. I, II and III only
2. I, III and IV only
3. II, III and IV only
4. I, II, III and IV

Assertion: Water transport across biological membranes is too specific and too rapid to be explained entirely by diffusion through the lipid layer.
Reason: Water molecules are so small that they move relatively freely across the lipid bilayer, even though the middle zone is hydrophobic.

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.

Assertion: Given equal cross sectional areas of xylem, a plant with larger-diameter vessels can move more water up its stems than a plant with narrower tracheids.
Reason: The volume of liquid moving in a column per second is inversely proportional to ${\mathrm{r}}^4$ where r is the radius of the column, at constant pressure.

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.

Reducing transpiration yet allowing the normal growth of a plant would be possible by:
1. increasing the potassium channels in the guard cells
2. increasing the level of carbon dioxide around the plant
3. growing the plant in soils with low water content
4. decreasing the relative humidity around the plant

Assertion: Blue light as a signal induces stomatal closure.
Reason: Blue light inhibits proton $\left[{\mathrm{H}}^{+}\right]$ transport.

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.