Question 1

Which structure or compartment is not part of the apoplast?

Accepted Answer

A)  the lumen of a xylem vessel
B)  the lumen of a sieve tube
C)  the cell wall of a mesophyll cell
D)  an extracellular air space
E)  the cell wall of a root hair B

Question 2

What is the driving force for the movement of materials in the phloem of plants?

Accepted Answer

A)  gravity
B)  a difference in osmotic water potential between the source and the sink.
C)  root pressure
D)  transpiration of water through the stomates
E)  adhesion of water to phloem sieve tubes B

Question 3

Loading of sucrose at the source and unloading at the sink in angiosperms maintains a pressure difference that keeps sap flowing through the sieve tubes.

Accepted Answer

A) True 
 B)False  True

Question 4

Which of the following is not an important component of the long-distance transport process in plants?

Accepted Answer

A)  The cohesion of water molecules.
B)  A negative water potential.
C)  The root parenchyma.
D)  The active transport of solutes.
E)  Bulk flow from source to sink.

Question 5

All of the following has an effect on water potential (¬)in plants except

Accepted Answer

A)  physical pressure.
B)  water-attracting matrices.
C)  dissolved solutes.
D)  osmosis.
E)  DNA structure.

Question 6

All of the following are adaptations that help reduce water loss from a plant except

Accepted Answer

A)  transpiration.
B)  sunken stomata.
C)  C4 photosynthesis.
D)  small, thick leaves.
E)  crassulacean acid metabolism.

Question 7

What regulates the flow of water through the xylem?

Accepted Answer

A)  passive transport by the endodermis
B)  the number of companion cells in the phloem
C)  the evaporation of water from the leaves
D)  active transport by sieve-tube members
E)  active transport by tracheid and vessel elements.

Question 8

All of the following involves active transport across membranes except

Accepted Answer

A)  the movement of mineral nutrients from the apoplast to the symplast.
B)  the movement of sugar from mesophyll cells into sieve-tube members in maize.
C)  the movement of sugar from one sieve-tube member to the next.
D)  K+ uptake by guard cells during stomatal opening.
E)  the movement of mineral nutrients into cells of the root cortex.

Question 9

Transpiration raises water potential in the leaf by producing a positive pressure potential. This higher water potential draws water from the xylem.

Accepted Answer

A) True 
 B)False

Question 10

Assume that a particular chemical interferes with the establishment and maintenance of proton gradients across the membranes of plant cells. All of the following processes would be directly affected by this chemical except

Accepted Answer

A)  photosynthesis.
B)  phloem loading.
C)  xylem transport.
D)  cellular respiration.
E)  stomatal opening.

Question 11

One is most likely to see guttation in small plants when the

Accepted Answer

A)  transpiration rates are high.
B)  root pressure exceeds transpiration pull.
C)  preceding evening was hot, windy, and dry.
D)  water potential in the stele of the root is high.
E)  roots are not absorbing minerals from the soil.

Question 12

The value for ¬ in root tissue was found to be -0.15 MPa. If you take the root tissue and place it in a 0.1 M solution of sucrose (¬ = -0.23), net water flow would

Accepted Answer

A)  be from the tissue into the sucrose solution.
B)  be from the sucrose solution into the tissue.
C)  be in both directions and the concentrations would remain equal.
D)  occur only as ATP was hydrolyzed in the tissue.
E)  be impossible to determine from the values given here.

Question 13

Pine seedlings grown in sterile potting soil grow much slower than seedlings grown in soil from the area where the seeds were collected. This is most likely because

Accepted Answer

A)  the sterilization process kills the root hairs as they emerge from the seedling.
B)  the normal symbiotic fungi are not present in the sterilized soil.
C)  sterilization removes essential nutrients from the soil.
D)  water and mineral uptake is faster when mycorrhizae are present.
E)  B and D

Question 14

Which of the following is a correct statement about sugar movement in phloem?

Accepted Answer

A)  Diffusion can account for the observed rates of transport.
B)  Movement can occur both upward and downward in the plant.
C)  Sugar is translocated from sinks to sources.
D)  Only phloem cells with nuclei can perform sugar movement.
E)  Sugar transport does not require energy.

Question 15

Some botanists argue that the entire plant should be considered as a single unit rather than a composite of many individual cells. Which of the following cellular structures cannot be used to support this view?

Accepted Answer

A)  cell wall
B)  cell membrane
C)  cytosol
D)  tonoplast
E)  symplast

Question 16

If ¬P = 0.3 MPa and ¬S = -0.45 MPa, the resulting ¬ is

Accepted Answer

A)  +0.75 MPa.
B)  -0.75 MPa.
C)  -0.15 MPa.
D)  +0.15 MPa.
E)  -0.42 MPa.

Question 17

Arrange the following five events in an order that explains the mass flow of materials in the phloem. 1. Water diffuses into the sieve tubes.
2) Leaf cells produce sugar by photosynthesis.
3) Solutes are actively transported into sieve tubes.
4) Sugar is transported from cell to cell in the leaf.
5) Sugar moves down the stem.

Accepted Answer

A)  2, 1, 4, 3, 5
B)  1, 2, 3, 4, 5
C)  2, 4, 3, 1, 5
D)  4, 2, 1, 3, 5
E)  2, 4, 1, 3, 5

Question 18

Ignoring all other factors, what kind of day would result in the fastest delivery of water and minerals to the leaves of a tree?

Accepted Answer

A)  cool, dry day
B)  warm, dry day
C)  warm, humid day
D)  cool, humid day
E)  very hot, dry, windy day

Question 19

When guard cells take up K+, they bow outward, widening the stomatal pore. Stomates close when K+ is actively transported out of the guard cells.

Accepted Answer

A) True 
 B)False

Question 20

Xylem vessels, found in angiosperms, have a much greater internal diameter than tracheids, the only xylem conducting cells found in gymnosperms. The tallest living trees, redwoods, are gymnosperms. Which of the following is an advantage of tracheids over vessels for long-distance transport to great heights?

Accepted Answer

A)  Adhesive forces are proportionally greater in narrower cylinders than in wider cylinders.
B)  The smaller the diameter of the xylem, the more likely cavitation will occur.
C)  Cohesive forces are greater in narrow tubes than in wide tubes of the same height.
D)  Only A and C are correct.
E)  A, B, and C are correct.

Exam 36: Transport in Vascular Plants

Which structure or compartment is not part of the apoplast?

What is the driving force for the movement of materials in the phloem of plants?

Loading of sucrose at the source and unloading at the sink in angiosperms maintains a pressure difference that keeps sap flowing through the sieve tubes.

Which of the following is not an important component of the long-distance transport process in plants?

All of the following has an effect on water potential (¬) in plants except

All of the following are adaptations that help reduce water loss from a plant except

What regulates the flow of water through the xylem?

All of the following involves active transport across membranes except

Transpiration raises water potential in the leaf by producing a positive pressure potential. This higher water potential draws water from the xylem.

Assume that a particular chemical interferes with the establishment and maintenance of proton gradients across the membranes of plant cells. All of the following processes would be directly affected by this chemical except

One is most likely to see guttation in small plants when the

The value for ¬ in root tissue was found to be -0.15 MPa. If you take the root tissue and place it in a 0.1 M solution of sucrose (¬ = -0.23) , net water flow would

Pine seedlings grown in sterile potting soil grow much slower than seedlings grown in soil from the area where the seeds were collected. This is most likely because

Which of the following is a correct statement about sugar movement in phloem?

Some botanists argue that the entire plant should be considered as a single unit rather than a composite of many individual cells. Which of the following cellular structures cannot be used to support this view?

If ¬P = 0.3 MPa and ¬S = -0.45 MPa, the resulting ¬ is

Ignoring all other factors, what kind of day would result in the fastest delivery of water and minerals to the leaves of a tree?

When guard cells take up K+, they bow outward, widening the stomatal pore. Stomates close when K+ is actively transported out of the guard cells.