Phloem transport differs from xylem transport as:

1.	Xylem transport requires active pumping at stomata, transport in phloem is passive.
2.	Phloem movement is solar powered, xylem movement occurs best in dark.
3.	Phloem carries fluid from the soil to the leaves, while xylem is the reverse.
4.	Phloem can reverse direction, depending on the activity of the "source" and "sink" of its materials but the flow in xylem is essentially unidirectional.

Advantages of transpiration to the plants include:
I. evaporative cooling.
II. mineral transport.
III. increased turgor.
1. I and II only
2. I and III only
3. II and III only
4. I, II and III

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.

The Casparian strip ensures that only selective substances may pass through the:
1. root hairs.
2. root cortex.
3. ground tissue.
4. endodermis.

Opening of guard cells is facilitated by:
I. accumulation of potassium accumulates within the guard cell.
II. movement of chloride into the guard cells.
III. membrane potential created by proton pumps.
1. I and II only
2. I and III only
3. II and III only
4. I, II and III

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.

Mangrove plants are able to survive in water logged regions as their pneumatophores have:
1. Stomata
2. Halophytes
3. Parenchyma
4. Lenticels

All the following will be a selective advantage in dry, hot conditions except:
1. CAM pathway
2. reduced leaves with stomata on the lower surface
3. a thick cuticle covering the fleshy leaves
4. mutant unable to produce ABA

“Sink” in the context of phloem transport of sucrose can normally be all the following except:
1. young growing leaf
2. shoot tip
3. storage organ in summer
4. mature leaf