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

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

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

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

The presence of chloroplasts in guard cells is important because:
1. chloroplasts have a light sensitive receptor to direct stomatal opening.
2. photosynthesis provides the energy necessary for synthesis of cellulose microfibrils.
3. oxygenic photosynthesis produces oxygen necessary to power active transport.
4. ATP is required to power proton pumps in the guard cell membranes.

CAM plants are not tall because:
1. tall CAM plants would be unable to move water and minerals to the top of the plant during the day.
2. tall CAM plants would be unable to supply sufficient sucrose for active transport of minerals into the roots during the day or night.
3. night time transpiration will put a lot of demand for water on tall CAM plants.
4. tall CAM plants have a very negative water potential in roots in night as transpiration occurs rapidly in night.

With respect to the mass flow translocation of phloem sap, the following events are given in the correct chronological sequence. Identify the statements that do not carry any mistake regarding the principles of the process:
I. In the storage sinks sucrose is removed into apoplast prior to entering the symplast of the sink.
II. Water moves out of the sieve tube cells by osmosis.
III. The phloem sugar is removed by the cortex of both stem and root, and is consumed by cellular respiration or else converted into starch.
IV. Finally relatively pure water is left in the phloem and this is thought to leave by osmosis or be drawn back into nearby xylem vessels by suction of the transpiration pull.
1. I, II and III only
2. I, II and IV only
3. II, III and IV only
4. I, II, III and IV

Arrange the following events in the correct chronological order during opening of the stomata:
I. An uptake of potassium ions occurs into the guard cells.
II. A proton pump drives protons (H⁺) from the guard cells.
III. Diffusion of water occurs into the guard cell through osmosis.
IV. The two guard cells lengthen by bowing apart from one another.
V. Negative ions flux into the guard cells to balance the influx of potassium.
1. I, III, II, IV, V
2. I, II, V, III, IV
3. II, I, V, III, IV
4. II, V, I, III, IV

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.

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