Question 1

A plant is exposed to a toxin that blocks ABA receptor sites in the plasma membrane.What is the likely consequence of this exposure?

Accepted Answer

A)  Oxygen deprivation will trigger the release of ethylene,which will in turn suppress root growth.
B)  Gibberellin production will increase,allowing the plant to access more nutrients in the soil.
C)  ABA will enter the cells by an alternative route and normal function will be restored.
D)  The plant will lose excess water through transpiration and suffer dehydration.
E)  The guard cells will become flaccid and gas exchange will cease. D

Question 2

The Calvin Cycle can only produce sugar if ________ can enter through the pores of the leaves.

Accepted Answer

A)  O2
B)  CO2
C)  water
D)  potassium
E)  N2 B

Question 3

Water is able to cross plant plasma membranes by a combination of

Accepted Answer

A)  osmosis and aquaporins.
B)  evaporation and diffusion.
C)  root pressure and turgidity.
D)  diffusion and phloem.
E)  transpiration and Casparian strips. A

Question 4

Most of the water that evaporates from leaves passes out through the

Accepted Answer

A)  cuticle.
B)  ends of xylem vessels.
C)  epidermis.
D)  spaces between epidermal cells.
E)  stomata.

Question 5

The movement of oxygen through the aquatic plant may depend on

Accepted Answer

A)  osmotic absorption by the roots.
B)  aquaporins.
C)  negative pressures created by transpiration.
D)  differences in the water potential of different tissues.
E)  aerenchyma tissue.

Question 6

The most important ion in controlling the movement of water into and out of the guard cells is

Accepted Answer

A)  sodium.
B)  hydrogen.
C)  carbon.
D)  nitrogen.
E)  potassium.

Question 7

The process by which water is "pulled" up through the xylem columns of plants as it evaporates out of the leaves is called

Accepted Answer

A)  respiration.
B)  transpiration.
C)  osmosis.
D)  anhydration.
E)  stomatization.

Question 8

Turgor is most directly related to the plant cells'

Accepted Answer

A)  total water potential.
B)  pressure potential.
C)  solute potential.
D)  osmosis.
E)  gravity potential.

Question 9

Mycorrhizal fungi interact with plants at the

Accepted Answer

A)  stomata.
B)  seed coat.
C)  roots.
D)  edge of ponds.
E)  cuticle.

Question 10

Mechanisms that evolved in plants to regulate the rate of water loss do not include

Accepted Answer

A)  becoming dormant during dry times of the year.
B)  losing leaves.
C)  producing leaves that are thick and hard.
D)  containing stomata in crypts or pits.
E)  increasing the number of water vacuoles in the cells.

Question 11

An increase in root pressure will result in the rapid release of abscisic acid (ABA)and the subsequent opening of the stomata.

Accepted Answer

A) True 
 B)False

Question 12

Which of the following actions occurs in many plants when CO2 concentrations are high?

Accepted Answer

A)  Guard cells lose turgor,and the stomata close.
B)  Water evaporates at a higher rate than usual.
C)  CAM photosynthesis fixes CO2 at night.
D)  Oxygen is used by plants for photosynthesis.
E)  Calcium ions are transported faster through the phloem.

Question 13

Halophytes are plants that live in saline soils.The high osmotic potential of the salt solution in the soil creates a very negative water potential.What can halophytes do so that water will flow into the roots?

Accepted Answer

A)  They can close their stomata so that less water is lost through transpiration.
B)  They can open all their stomata so that transpiration "pulls" more water into the roots.
C)  They can increase the solute concentration in their roots creating a water potential that is more negative than the soil.
D)  They can pump ions out of the plant creating a water potential in the roots that is more positive than the soil.
E)  They can remove the mycorrhizal fungi from their roots decreasing the competition for water.

Question 14

The plasma membranes of root hair cells contain a variety of protein transport channels through which specific ions are transported,even against large concentration gradients,by

Accepted Answer

A)  electron pumps.
B)  carbohydrate pumps.
C)  water pumps.
D)  proton pumps.
E)  root pumps.

Question 15

If the soil around a plant is treated with a fungicide,the plant may experience a decline in DNA synthesis.

Accepted Answer

A) True 
 B)False

Question 16

On a short-term basis,water loss in plants may be controlled by the

Accepted Answer

A)  bending of the petioles on the leaves.
B)  closing of the stele in the roots.
C)  closing of the stomata in the leaves to limit transpiration.
D)  opening of the stomata in the leaves to allow more carbon dioxide to enter.
E)  opening the Casparian strips in the roots.

Question 17

You a given a plant tissue in lab and asked to determine if the tissue is a source or a sink.Microscopic analysis reveals an abundance of colorless parenchyma cells with plastids.Only one biochemical test reacts positively with your sample.In the presence of iodine,the plastids turn a dark purplish color.Based on this information you determine your sample is

Accepted Answer

A)  a source because your sample is rich in carbohydrates.
B)  a source because your sample contains plastids.
C)  a sink because your sample is rich in carbohydrates.
D)  both a source and sink because it contains both plastids and carbohydrates.

Question 18

Mangrove plants live in areas regularly flooded with salt water.Which of these is not a possible mechanism for controlling their salt balance?

Accepted Answer

A)  The roots block salt uptake.
B)  The succulent leaves contain large quantities of water that dilute salt that is absorbed.
C)  Absorbed salt is secreted from special salt glands.
D)  Modified roots emerge above the water level and help oxygen diffuse into the roots.
E)  Excess salt is stored in special tissues.

Question 19

A large watermelon fruit is very heavy and contains nearly 90% water.Since the skin of a watermelon is thick and lacks stomata,transpiration does not "pull" water into the watermelon.So,how does all that water get into the fruit?

Accepted Answer

A)  Root pressure pushes water into the watermelon.
B)  Water enters by osmosis from the soil.
C)  Water is pumped in by active transport.
D)  Water is transported in the phloem along with the sugars while they are being translocated into the fruit.
E)  Watermelons,like other fruit,contain an abundance of xylem.

Question 20

The pressure-flow hypothesis describes

Accepted Answer

A)  how hormones move through the phloem.
B)  how carbohydrates enter the sieve tubes.
C)  how carbohydrates in solution move through the phloem.
D)  how water and minerals move through the xylem.
E)  how carbohydrates and minerals move through the xylem.

Exam 36: Transport in Plants