Deck 38: Transport in Plants

Question 1

Turgor is most directly related to the plant cells'

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

Answer 1

B

Question 2

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

A)Guard cells lose turgor,and the stomata partially 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.

Answer 2

A

Question 3

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

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

Answer 3

C

Question 4

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

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 5

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

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

Question 6

Even in the absence of transpiration,some water can move into the roots and partially up the xylem columns.This phenomenon is due to

A)flooding.
B)stomatal opening.
C)root pressure.
D)proton pumps.
E)phloem translocation.

Question 7

Cavitation can occur when what happens?

A)Root pressure pushes water up the xylem.
B)Starch grains block the sieve tubes.
C)Gas bubbles expand inside a tracheid or vessel member.
D)Stomates get stuck closeD.
E)Clouds block sunlight shining on the leaves.

Question 8

A plant will usually wilt when which component of water potential reaches 0 MPa?

A)solute potential
B)turgor pressure
C)total water potential
D)gravity potential

Question 9

Which of the following statements does not apply to aquaporins?

A)They are water transport channels.
B)They are unique to plant cells.
C)They occur in the plasma membrane.
D)They speed up osmosis.
E)They do not alter the direction of water movement.

Question 10

Some plants are able to endure frequent flooding events because they contain a tissue with loose parenchyma cells and large air spaces called

A)xylem.
B)spongy mesophyll.
C)pneumatophores.
D)aerenchyma.
E)epidermal tissuE.

Question 11

Which of the following is not transported within the plant by the xylem and/or the phloem?

A)dissolved minerals
B)sucrose
C)growth-regulating hormones
D)water
E)starch

Question 12

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

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

Question 13

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

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

Question 14

Most of the water absorbed by the plant enters through the

A)root apical meristem.
B)root cap.
C)root hairs.
D)stomata.
E)lenticels.

Question 15

Water moves through a plant by each of the following methods except

A)from cell to cell through plasmodesmatA.
B)through the Casparian strip.
C)through the spaces between cell protoplasts.
D)through vessel members.
E)from cell to cell across plasma membranes.

Question 16

The movement of oxygen through the aquatic plant may depend on

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 17

The process by which water is "pulled" up through the xylem columns of plants and evaporated out of the leaves is called

A)root pressure.
B)transpiration.
C)osmosis.
D)adhesion of water molecules.
E)cohesion of water molecules.

Question 18

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

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

Question 19

Which of the following statements about transport through phloem is true?

A)Transport only occurs from the roots to the shoot.
B)It is aided by root pressure.
C)The direction of flow can change at different times if the sources and sinks change.
D)No energy is requireD.
E)Mostly dissolved starch is transported.

Question 20

Stomatal opening requires each of the following conditions except

A)expenditure of energy.
B)a reduction of turgor in the guard cells.
C)water entering the guard cells by osmosis.
D)a lower water potential in the guard cells.
E)pumping of potassium ions into the guard cells.

Question 21

The uneven distribution of an impermeable solute on either side of a membrane will result in

A)an increase in oxygen deprivation.
B)proton pumping.
C)root pressure.
D)osmosis.
E)stomatal closing.

Question 22

Which of these factors does not have a direct or indirect effect on how much the stomates are open?

A)temperature
B)carbon dioxide
C)relative humidity
D)light
E)chlorophyll

Question 23

Which of the following hormones increases when plants are flooded?

A)gibberellin
B)auxin
C)ethylene
D)cytokinin
E)abscissic acid

Question 24

The pressure-flow hypothesis describes

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.

Question 25

Pure water without applied pressure has a water potential that is equal to

A)infinity.
B)0.0 MPa.
C)1.6 MPa.
D)-2.0 MPa.
E)atmospheric pressurE.

Question 26

Which of the following plant hormones plays a primary role in triggering K⁺ to pass rapidly out of guard cells?

A)gibberellic acid
B)auxin
C)indoleacetic acid
D)ethylene
E)abscisic acid

Question 27

Water may be lost in liquid form at the edges of the leaves of herbaceous plants through a process known as

A)guttation.
B)cohesion.
C)phloem loading.
D)mesophyll adhesion.
E)aeration.

Question 28

Water molecules can "stick" to certain surfaces by

A)adhesion.
B)cohesion.
C)root pressure.
D)water pressure.
E)pneumatophores.

Question 29

In Cell 2,

A) $\Psi$ _p = 0.75 MPa and $\Psi$ _w = 0.0 MPA.
B) $\Psi$ _p = 0.0 MPa and $\Psi$ _w = -0.75 MPa.
C) $\Psi$ _p = -0.25 MPa and $\Psi$ _w = -0.5 MPa.
D) $\Psi$ _p = +0.25 MPa and $\Psi$ _w = -0.5 MPa.
E) $\Psi$ _p = +0.25 MPa and $\Psi$ _w = +0.25 MPa.

Question 30

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

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 31

The process of moving water through a plant by transpiration works because water molecules stick to each other with

A)turgor pressure.
B)osmosis.
C)ionic bonds.
D)adhesion.
E)hydrogen bonds.

Question 32

Which of the following does not require expenditure of energy?

A)accumulation of ions inside a cell
B)transport against a concentration gradient
C)flow of sucrose and other carbohydrates through sieve tubes
D)the loading and unloading of carbohydrates from the sieve tubes
E)opening or closing stomata

Question 33

Most carbohydrates manufactured in leaves and other photosynthetic parts are transported through the phloem to the rest of the plant by the process of

A)transpiration.
B)translocation.
C)osmosis.
D)receptor-mediated transport.
E)turgor pressurE.

Question 34

Some plants can tolerate flooding conditions by

A)formation of aerenchymA.
B)opening their lenticels.
C)forming additional adventitious roots.
D)shedding their bark.
E)pumping water out of their roots.

Question 35

Photosynthesis can occur only if the stomata are open to allow the entry of

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

Question 36

Plants living in standing water often face which of the following problems?

A)increased CO₂ levels
B)chilling of the roots
C)oxygen deprivation
D)loss of stomata
E)harmful root pressure

Question 37

In Cell 1,

A) $\Psi$ _p = 0.0 MPa and $\Psi$ _w = 0.0 MPA.
B) $\Psi$ _p = 0.0 MPa and $\Psi$ _w = -1.0 MPa.
C) $\Psi$ _p = +0.5 MPa and $\Psi$ _w = -0.5 MPa.
D) $\Psi$ _p = -0.5 MPa and $\Psi$ _w = -0.5 MPa.
E) $\Psi$ _p = 0.0 MPa and $\Psi$ _w = +0.5 MPa.

Question 38

Which of the following equations represents the total water potential of a plant?

A)s² + p² = w²
B)Y_s = Y_p + Y_w
C)Y_p = Y_w + Y_s
D)Y_w = Y_p + Y_s
E)Y_w = Y_s /Y_p

Question 39

Which of the following essential ions is not transported elsewhere once it has been deposited in plant parts?

A)sodium
B)potassium
C)calcium
D)magnesium
E)chloride

Question 40

To maintain guard cell turgor,which of the following must occur?

A)Potassium ions are pumped out.
B)Energy is constantly expended.
C)Water exits by osmosis.
D)Stomata take up oxygen.
E)Transpiration occurs.

Question 41

Choose the letter of the best match from the following:
A.abscisic acid
B.trichomes
C.aquaporin
D.endodermis
E.stomate
Increases humidity at leaf surface.

Question 42

A large watermelon fruit is very heavy and contains nearly 90% water.Since the skin of a watermelon is thick and contains no stomates,there is no way to evaporate water out of the watermelon to "pull" water into the watermelon by transpiration.So,how does all that water get into the fruit?

A)Root pressure pushes water into the watermelon.
B)Water enters by osmosis.
C)Water is pumped in by active transport.
D)Water,main part of the sap,is transported in the phloem along with the sugars while they are being translocated into the fruit.
E)Watermelons lying on the ground absorb water directly from the soil.

Question 43

Which of these is not a reason that aphids feed on phloem?

A)Phloem is under positive pressure,so when the aphid pierces a phloem tube,sap is pushed into its mouth.
B)Xylem is under negative pressure,so it would be very difficult to suck the fluids.
C)Phloem contains high concentrations of sugars,as well as some minerals and other nutrients.
D)Xylem contains mostly water and fewer nutrients.
E)In soft herbaceous plants,phloem is more accessible than xylem.

Question 44

Which of these situations regarding phloem sources and sinks is not correct?

A)The seeds in a developing fruit are a strong sink.
B)The shoot tip and young leaves are strong sources for the leaves below.
C)Potentially,sugars could be transported from any part of a plant to any other part.
D)In a seedling,the cotyledons would be strong sources.
E)During autumn,one of the strongest sinks is the storage tissue in the roots.

Question 45

Choose the letter of the best match from the following:
A.abscisic acid
B.trichomes
C.aquaporin
D.endodermis
E.stomate
Pore in plasma membrane that allows water movement.

Question 46

Which of these structures is not likely to contain significant amounts of aerenchyma tissue?

A)mangrove pneumatophores
B)rice roots
C)water lily leaves
D)cypress "knees"
E)coconut fruits

Question 47

Choose the letter of the best match from the following:
A.abscisic acid
B.trichomes
C.aquaporin
D.endodermis
E.stomate
Triggers K⁺ to pass rapidly out of guard cells.

Question 48

In Cell 3,

A) $\Psi$ _p = 0.0 MPa and $\Psi$ _w = -0.5 MPA.
B) $\Psi$ _p = 0.0 MPa and $\Psi$ _w = 0.0 MPa.
C) $\Psi$ _p = +0.5 MPa and $\Psi$ _w = -0.5 MPa.
D) $\Psi$ _p = -0.5 MPa and $\Psi$ _w = -0.5 MPa.
E) $\Psi$ _p = 0.0 MPa and $\Psi$ _w = +0.5 MPa.

Question 49

Most often,the largest gradient in water potential is between

A)roots and soil water.
B)root xylem and shoot xylem.
C)xylem and phloem.
D)leaf cells and the intracellular spaces inside the leaves.
E)the relative humidity inside the leaf and the relative humidity outside the plant.

Question 50

Mycorrhizal fungi interact with plants at the

A)stomates.
B)seed coat.
C)roots.
D)edge of ponds.
E)cuticlE.

Question 51

When maple trees are tapped in the spring there are no leaves to promote transpiration.What process and pressure still allows the upward movement of sap so maple syrup can be collected.

A)transpiration in the xylem.
B)water potential gradients.
C)translocation in the phloem.
D)osmosis and root pressure.
E)low water potential.

Question 52

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?

A)They can close their stomates so that less water uptake is needed.
B)They can open their stomates so that transpiration can "pull" more strongly to get the water into the roots.
C)They can increase the solute concentrations in their roots more than the solute concentration of the soil.
D)They can pump ions out of their roots.
E)They form symbiotic relationships with mycorrhizal fungi.

Question 53

Choose the letter of the best match from the following:
A.abscisic acid
B.trichomes
C.aquaporin
D.endodermis
E.stomate
Pore in leaf that regulates gas exchange.

Question 54

Choose the letter of the best match from the following:
A.abscisic acid
B.trichomes
C.aquaporin
D.endodermis
E.stomate
Regulates movement of mineral ions into root xylem.