Chapter 36 – Mastering Biology

Which tissue acts as a filter on the water absorbed by root hairs?

endodermis Endodermal cells filter solutes from water and allow them to pass through to the vascular tissue.

True or false? Root pressure can move water a long distance up the xylem because of the higher water potential of the xylem in comparison to the water potential in the surrounding cells.

False Root pressure can move water a short distance up the xylem because of the lower water potential of the xylem in comparison to the water potential in the surrounding cells.

Which of the following statements about the distribution of sap throughout a plant is true?

The mechanism that explains the movement of sugars throughout a plant is called the pressure-flow hypothesis.

Which term describes an area where sugars are used or stored?

Sink A sink is an area where sugars are used or stored; typically, these are the roots and fruits of a plant.

Which of the following statements about xylem transport is true?

Water and minerals move through the root cortex into the xylem and upward through the stem and into leaves. Water and minerals that are taken up in the soil are transported from roots to leaves by the xylem.

What characterizes the rates of photosynthesis and transport in a plant on a dry cloudy day?

Both the photosynthesis and transpiration rates are low. On a cloudy day with low soil moisture, the photosynthesis rate is low and stomata are closed, so the transpiration rate is low.

True or false? The rate of sugar transport in a plant depends on the rate of photosynthesis, the rate of transpiration, and the difference in turgor pressure between the source and the sink.

False While the rate of photosynthesis and the difference in turgor pressure between the source and the sink do influence the rate of sugar transport in the phloem, the rate of transpiration does not; transpiration mainly influences the rate of water transport through the xylem.

The channels indicated by the pointer, are _____.
The figure shows a structure of the root. The arrow indicates the channel between the cell from the outer layer of the root and the inner one.

plasmodesmata
tight junctions
mycorrhizae
gap junctions
desmosomes

plasmodesmata (Water and ions can pass from cell to cell via these channels. Also, recall that plasmodesmata are a type of cell junction.)

Which of these are symbiotic associations?
root hairs
apoplasts
Casparian strips
mycorrhizae
symplast

mycorrhizae Mycorrhizae are mutualistic associations of roots and fungi.

To view the animation, https://session.masteringbiology.com/myct/itemView?assignmentProblemID=111575880&offset=next# . Then click on the image to start the animation.

This is an animation of the movement of water and ions through the root ______.

via the apoplastic route The animation illustrates water and ions moving along a cell wall continuum.

In roots the _____ forces water and solutes to pass through the plasma membranes of _____ cells before entering the _____.

Casparian strip … endodermis … xylem The Casparian strip is a waterproof barrier that forces water and solutes to pass through the plasma membranes of endodermis cells.

_____ provide(s) the major force for the movement of water and solutes from roots to leaves.

transpiration Transpiration, the evaporation of water from leaves, exerts a pull that bears the primary responsibility for the movement of water and solutes from roots to leaves.

_____ bonds are responsible for the cohesion of water molecules.

hydrogen Hydrogen bonds among water molecules are responsible for the tendency of those molecules to stick together.

_____ cells are the cells that regulate the opening and closing of stomata, thus playing a role in regulating transpiration.

Guard Guard cells regulate the opening and closing of stomata.