Water potential is best defined as the:
1. product of turgor pressure and pressure potential
2. difference between pressure potential and osmotic potential
3. combination of pressure potential and solute potential
4. difference between pressure potential and osmotic potential

Xylem in plants does not:
1. conduct material upward from the roots.
2. conduct materials within the dead cells.
3. transport large amounts of sugars and amino acids.
4. have a lower water potential than soil does.

Surface area for water absorption from soil by the roots of the plants is increased due to all of the following except:
1. root hairs
2. endodermis
3. mycorrhizae
4. fibrous arrangement of the roots

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

All the following statements regarding root hair in plants are true except:

Root hair cells have ${\mathrm{H}}^{+}$ pumps that:
1. establish ATP gradients
2. acquire minerals from the soil
3. pressurize xylem transport
4. eliminate excess electrons

The Casparian strip in plant roots:
1. is located in the walls of the outermost portion of the cortex.
2. is composed predominantly of lignin and hence is impermeable to water.
3. ensures active uptake of all minerals by the roots.
4. ensures that all water and dissolved substances must pass through a cell membrane before entering the vascular cylinder.

Translocation in xylem will not be facilitated by:
1. The cohesion of water molecules.
2. A negative water potential.
3. The root parenchyma.
4. The active transport of solutes.

It is a common observation that pine seedlings grown in sterile potting soil grow much slower than seedlings grown in soil from the area where the seeds were collected. The most probable cause for this would be:

The flow of water through the xylem is regulated by:
1. passive transport of mineral ions by the root endodermis.
2.the number of nuclei in the companion cells in the phloem.
3. the evaporation of water from the leaves.
4. active transport by tracheid and vessel elements.