Deck 34: Transport in Plants

Question 1

Generally, the energy for pumping protons outside of a plant cell comes most directly from ____.

A)sunlight
B)starch
C)ATP
D)diffusion
E)glucose

Answer 1

C

Question 2

The longest limb on the Angel Oak on Johns Island, South Carolina, is ____.

A)10 m
B)17 m
C)40 m
D)57 m
E)75 m

Answer 2

D

Question 3

Water potential, the inherent capacity of water molecules to move from one site to another when conditions dictate, is typically represented by the Greek letter ____.

A)a ​
B)g
C)y
D)p
E)q

Answer 3

C

Question 4

The movement of NH₄⁺ ions into a cell down an electrochemical gradient created by H⁺ pumping is an example of ____.

A)an ion pump
B)passive diffusion
C)facilitated diffusion
D)secondary active transport
E)passive transport

Question 5

Individual plant cells typically gain or lose water mainly via ____.

A)facilitated diffusion
B)symport
C)guttation
D)osmosis
E)bulk flow

Question 6

A cell expends energy when moving substances against a gradient during ____.

A)symport
B)passive diffusion
C)active transport
D)facilitated diffusion
E)antiport

Question 7

Which plant organelle stores solutes and plays a major role in maintaining turgor pressure?

A)nucleus
B)cell wall
C)chloroplast
D)vacuole
E)mitochondrion

Question 8

In a living plant cell in a living plant, you would expect to find protons ____.

A)moving out of the cell via passive diffusion
B)being actively pumped into the cell
C)moving out of the cell via facilitated diffusion
D)being actively pumped out of the cell
E)moving into the cell via passive diffusion

Question 9

When a cell contains enough water that the plasma membrane presses tightly against the cell wall, it is said to be ____.

A)palsmolytic
B)tight
C)wilted
D)full
E)turgid

Question 10

When the protoplast shrinks away from the cell wall, it is called ____.

A)plasmolysis
B)tight
C)wilted
D)turgid
E)full

Question 11

The Angel Oak on Johns Island, South Carolina is estimated to be up to ____ years old. ​

A)300 ​
B)1000
C)1400
D)2000
E)2400

Question 12

Consider a living plant cell in a living leaf that has a higher water potential than the fluids surrounding the cell. In such a situation there should be ____.

A)a net flow of water out of the cell
B)gain of water by the cell only if the cell's pressure potential is high enough
C)no net flow of water into or out of the cell
D)a net flow of water into the cell
E)gain of water by the cell only if the cell's pressure potential is low enough

Question 13

Phloem does not transport ____.

A)carbohydrates
B)hormones
C)amino acids
D)fatty acids
E)nitrate

Question 14

The membrane potential refers to the ____ across a cell membrane.

A)difference in water concentration
B)charge difference
C)rate of movement
D)distance
E)difference in salt concentration

Question 15

In a living plant cell in a living plant, you would expect the cytoplasm to be ____.

A)much more negatively charged than the fluid outside the cell ​
B)essentially the same charge as the fluid outside the cell
C)slightly more positively charged than the fluid outside the cell
D)much more positively charged than the fluid outside the cell
E)slightly more negatively charged than the fluid outside the cell

Question 16

Consider a living plant cell in a living leaf that is not wilted. The solute potential ( y _S )of such a cell ____ than that in the fluids surrounding the cell.

A)is typically lower ​
B)varies widely from higher to lower
C)is typically higher
D)is typically about the same as
E)is typically less negative

Question 17

Sucrose moves into a cell against its concentration gradient at the same time that protons move into the cell along their concentration gradient. This is an example of ____.

A)symport
B)passive diffusion
C)antiport
D)facilitated diffusion
E)active transport

Question 18

Aquaporins are ____.

A)channel proteins for water
B)carrier proteins for solutes
C)channel proteins for solutes
D)carrier proteins for water
E)carrier proteins for water and solutes

Question 19

Consider a living plant cell in a living leaf that is not wilted. The pressure potential ( y _P )of such a cell ____ than that in the fluids surrounding the cell.

A)is typically lower ​
B)varies widely from higher to lower
C)is typically higher
D)is typically about the same as
E)is typically less negative

Question 20

The typical movement of xylem sap from roots to shoot parts is best described as ____.

A)facilitated diffusion
B)symport
C)guttation
D)osmosis
E)bulk flow

Question 21

Most mineral ions that plants need are moved into the ____.

A)symplast via active transport
B)transmembrane pathway via bulk flow
C)apoplast via facilitated diffusion
D)symplast via facilitated diffusion
E)the apoplast via bulk flow

Question 22

Many plants wind up with a Na⁺ concentration that is considerably lower than that of the surrounding soil. Which of these plays a key role in allowing for such a difference to exist?

A)water potential
B)aquaporins
C)root cap
D)endodermis
E)tonoplast

Question 23

A plant cell with a y _P = 0.2 MPa maintains a constant volume when bathed in a solution that has a y _S = - 0.2 MPa and is in an open container. What do you know about the cell?

A)The cell has a y _S = 0.4 MPa.
B)The cell has a y _S = - 0.2 MPa.
C)The cell has a y _S = - 0.4 MPa.
D)The cell has a y = - 0.4 MPa.
E)The cell has a y = 0.2 MPa

Question 24

Active transport in plant root cells requires that those cells have access to O₂. Normally there is enough O₂ available in air pockets in the soil, but flooded soil has very little O₂. Thus, unless they have special adaptations, plants in flooded soil effectively have no active transport in their roots. Which of the following should you expect to occur for trees without special adaptations to flooding after several days in flooded soil?

A)excess uptake of water and minerals in the xylem only
B)wilting of their leaves
C)bursting of leaf cells due to excess water flow
D)excess water pushed out at the margins of their leaves only
E)excess uptake of water and minerals in the xylem, and excess water pushed out at the margins of their leaves

Question 25

Water that moves through living cells in a root is following the ____.

A)symplastic pathway only
B)transmembrane and symplastic pathways
C)transmembrane pathway only
D)apoplastic, transmembrane, and symplastic pathways
E)apoplastic pathway only

Question 26

If the y of surrounding soil is higher than that in living root epidermal cells, then water should ____.

A)leave the root cells, making them flaccid
B)enter the root cells, making them turgid
C)leave the root cells, making them turgid
D)enter the root cells, making them flaccid
E)none of these accurately describe water movement

Question 27

If a living plant cell is placed in a beaker with pure water, it will take up water until ____.

A)within the cell y _P = -y _S
B)it bursts
C)its y _P = 0
D)its y _S = y _S of the pure water
E)its y _S = 0

Question 28

Suppose two living plant cells are in contact with each other so that water, but not solutes, can pass between them. The cells have the same water potential. One cell has y _P = 0.3 MPa and y _S = - 0.5 MPa, while the other cell has y _S = - 0.3 MPa. What is the y _P of the second cell?

A)y _P = - 0.8 MPa ​
B)y _P = 0 MPa
C)y _P = 0.5 MPa
D)y _P = 0.8 MPa
E)y _P = 0.1 MPa

Question 29

According to the cohesion-tension mechanism of water transport, cohesion occurs because ____.

A)waxy coatings on insides of xylem keep water molecules together in the xylem ​
B)evaporation removes water from the leaves
C)water molecules tend to form hydrogen bonds with each other
D)water is pushed into the xylem by bulk flow
E)water is pushed into the xylem by phloem pressure

Question 30

Suppose a living plant cell has y _P = 0.4 MPa and y _S = - 0.5 MPa. If the plant cell is placed into a beaker filled with a solution with y = y _S = - 0.9 MPa, then the cell should ____.

A)take up water until it bursts
B)lose water until its y = y of the solution
C)take up water until within the cell y _P = -y _S
D)take up water until its y = y _S of the solution
E)lose water until its y _S = its y _P

Question 31

The majority of the water in xylem sap typically ____.

A)is used in capturing light energy
B)becomes part of new plant cells
C)is used to make sugars
D)is stored in older plant cells
E)evaporates into the air

Question 32

Approximately ____ percent of water that enters a plant's roots is used for photosynthesis and other parts of metabolism and growth.

A)1-3
B)2-5
C)5-10
D)15-20
E)25-30

Question 33

The Casparian strip of the endodermis stops water from the ____ before it reaches the stele.

A)symplastic pathway only
B)transmembrane and symplastic pathways
C)transmembrane pathway only
D)apoplastic, transmembrane, and symplastic pathways
E)apoplastic pathway only

Question 34

Suppose a living plant cell has y = y _S = - 0.5 MPa. If the plant cell is placed into a beaker filled with a solution with y = 0, then the cell should ____.

A)take up water until it bursts
B)lose water until its y = y of the solution
C)take up water until within the cell y _P =   0
D)take up water until its y = y _S of the solution
E)lose water until its y _S = its y _P

Question 35

The ____ prevents important substances in the xylem form leaking into the root cortex.

A)primary xylem
B)root hairs
C)endodermis
D)tonoplasts
E)pericycle

Question 36

If a living plant cell is placed in a beaker with a solution that has a y value lower than the y value of the plant cell, the plant cell will ____.

A)take up water until it bursts
B)lose water until its y = y of the solution
C)take up water until within the cell y _P = -y _S
D)take up water until its y = y _S of the solution
E)lose water until its y _S = its y _P

Question 37

Water that moves through nonliving regions of root, such as air spaces in root tissue, is following the ____.

A)symplastic pathway only
B)transmembrane and symplastic pathways
C)transmembrane pathway only
D)apoplastic, transmembrane, and symplastic pathways
E)apoplastic pathway only

Question 38

What is the y _P of a living plant cell that has y = - 0.2 MPa and y _S = - 0.4 MPa?

A)y _P = - 0.6 MPa
B)y _P = 0.08 MPa
C)y _P = - 0.2 MPa
D)y _P = 0.2 MPa
E)y _P = 0.5 MPa

Question 39

The loss of water vapor from above ground plant parts is called ____.

A)passive transport
B)transpiration
C)root pressure
D)evaporation
E)sublimation

Question 40

Water can move inside a root via the ____.

A)symplastic pathway only ​
B)transmembrane and symplastic pathways
C)transmembrane pathway only
D)apoplastic, transmembrane, and symplastic pathways
E)apoplastic pathway only

Question 41

Stomata close when ____ guard cells and they become ____.

A)active transport pumps H⁺ into; turgid
B)active transport of H⁺ stops in; flaccid
C)active transport pumps H⁺ out of; turgid
D)active transport pumps H⁺ into; flaccid
E)active transport of H⁺ stops in; turgid

Question 42

The most widely accepted and supported model that explains the movement of xylem sap is the ____ mechanism.

A)cohesion-tension
B)translocation
C)pressure flow
D)osmosis
E)transpiration

Question 43

According to the cohesion-tension mechanism of water transport, ____ does not contribute to the flow of the xylem sap?

A)hydrogen bonding between water molecules ​
B)adhesion of water molecules to the xylem vessel walls
C)evaporation of water from the leaves
D)water potential in leaf cells below that of the leaf xylem
E)root pressure

Question 44

Stomata generally close in response to ____.

A)the release of abscisic acid by the roots
B)a drop in CO₂ concentration in leaf air spaces
C)exposure to red light
D)a drop in O₂ concentration in leaf air spaces
E)an increase in CO₂ concentration in the leaf air spaces

Question 45

In most plants stomata are ____.

A)open during the night and closed during the day
B)nearly always open
C)closed only when guard cells are not exposed to sunlight
D)almost never open
E)open during the day and closed during the night

Question 46

The most prominent known role in the opening and closing of stomata is played by____ ions.

A)Ca²⁺
B)Cl ^-
C)K⁺
D)NH₄⁺
E)Na⁺

Question 47

The movement of xylem sap is best described from the ____ to the ____.

A)shoot system; root system
B)sinks; sources
C)root system; shoot system
D)sources; sinks
E)shoot system; sinks

Question 48

The major cost to plants for having cuticle-covered epidermis in the shoot system to reduce water loss is reduced ____ uptake.

A)carbon dioxide
B)potassium
C)nitrogen
D)calcium
E)oxygen

Question 49

Experiments have shown that sap transport peaks ____.

A)in the early morning
B)by mid-morning
C)at midday
D)in the evening
E)overnight

Question 50

In herbaceous plants, the stress-related closing of stomata is regulated by ____.

A)sunlight
B)ion concentrations in the xylem
C)CO₂ concentration
D)O₂ concentration
E)abscisic acid

Question 51

You would expect essentially no transpiration to occur in conditions of ____.

A)brisk winds
B)100 percent relative humidity
C)no winds
D)one percent relative humidity
E)hot air temperature and no winds

Question 52

Stomata generally open in response to ____.

A)the release of abscisic acid by the roots
B)a drop in CO₂ concentration in leaf air spaces
C)exposure to red light
D)a drop in O₂ concentration in leaf air spaces
E)an increase in CO₂ concentration in the leaf air spaces

Question 53

A plant stoma is found between two ____.

A)leaves
B)root hairs
C)xylem veins
D)trichomes
E)guard cells

Question 54

The principal driving force for guttation is ____.

A)passive transport
B)sunlight
C)root pressure
D)upward pressure as sugar is forced into the roots
E)pumping by the xylem cells

Question 55

An air temperature rise of 10 ° C will typically ____ evaporation from leaves.

A)completely eliminate
B)double the rate of
C)mostly eliminate
D)triple the rate of
E)quadruple the rate of

Question 56

Which factor has little effect on the rate of transpiration?

A)air temperature
B)relative humidity
C)air movement
D)the amount of direct solar radiation
E)daily fluctuations in atmospheric carbon dioxide concentrations

Question 57

Stomata are opened when ____ guard cells and they become ____.

A)active transport pumps H⁺ into; turgid
B)active transport of H⁺ stops in; flaccid
C)active transport pumps H⁺ out of; turgid
D)active transport pumps H⁺ into; flaccid
E)active transport of H⁺ stops in; turgid

Question 58

In CAM plants, such as cacti, stomata are ____.

A)open during the night and closed during the day
B)nearly always open
C)closed only when guard cells are not exposed to sunlight
D)almost never open
E)open during the day and closed during the night

Question 59

Stomata open when K⁺ concentration in guard cells ____, followed by water ____ the guard cells by osmosis.

A)increases; entering
B)decreases; entering
C)decreases; leaving
D)increases; leaving
E)increases H^+; leaving

Question 60

Theoretically, based on the cohesion-tension mechanism, the maximum height for the tallest trees should be about ____.

A)50 ft
B)130 m
C)6 ft
D)3 m
E)75 m

Question 62

Over ____ of analytes in plant samples identified from mass spectrometry are classified as "unknown".

A)6%
B)16%
C)46%
D)60%
E)96%

Question 63

The movement of phloem sap is best described from the ____ to the ____.

A)shoot system; root system
B)sinks; sources
C)root system; shoot system
D)sources; sinks
E)shoot system; sinks

Question 64

The most widely accepted and supported model that explains the movement of phloem sap in flowering plants is the ____ mechanism.

A)cohesion-tension
B)translocation
C)pressure flow
D)osmosis
E)transpiration

Question 65

The hypothesis that high pressure forces phloem sap to flow was tested and supported by studies using ____.

A)caterpillars
B)radiolabeled hormones
C)vacuum chambers
D)aphids
E)radiolabeled sugars

Question 66

Metabolomics is based on the premise that ____.

A)plant mitochondria are unique to harnessing ATP to develop alternative energy sources
B)plant chloroplasts are unique to harnessing light for energy
C)harnessing the 200,000 to 1 million different chemicals produced by plant metabolism for human needs is increasingly important
D)plant metabolism is difficult to manipulate
E)plant metabolism is simple to manipulate

Question 67

Phloem sap does not normally contain ____.

A)carbohydrates ​
B)hormones
C)water
D)amino acids
E)nitrate

Question 68

In phloem movement, ____ does not serve as a source.

A)photosynthesizing cells in a leaf
B)roots
C)photosynthesizing cells in a stem
D)food storage cells in a stem
E)soil

Question 69

Researchers in Finland determined the function of NAC proteins in the formation of ____.

A)glucose
B)root hairs
C)chloroplasts
D)xylem
E)sieve tube elements

Question 70

Leaves on the lower part of a bush primarily feed the ____.

A)roots
B)leaf tips
C)stems
D)upper leaves
E)flowers

Question 71

The main form in which sugars are transported in the phloem sap is ____.

A)glucose
B)lactose
C)starch
D)sucrose
E)fructose

Question 72

At a source the phloem typically has a water potential that is ____ that in surrounding xylem.

A)lower than
B)about the same as
C)higher than
D)exactly the same as
E)less negative than

Question 73

Loading of most carbohydrates produced by photosynthesis into companion cells at a source occurs by ____.

A)osmosis
B)proton pumping
C)suction from unloading at a sink
D)active transport
E)diffusion of water from the xylem

Question 74

"Honeydew" is essentially ____.

A)xylem sap forced out of the margins of leaves
B)xylem sap harvested by honeybees
C)phloem sap harvested as syrup
D)xylem sap separated from syrup
E)phloem sap leaving the anus of an aphid

Question 75

Sieve elements differentiate through a process called ____ that causes the destruction of certain cell structures.

A)adsorption
B)rotting
C)ecdysis
D)autolysis
E)translocation

Question 76

In phloem movement, ____ cannot serve as a sink.

A)young leaves
B)young roots
C)developing fruits
D)tulip bulbs after the plant has bloomed
E)soil

Question 77

The general term for long-distance transport of substances in plants is called ____.

A)cohesion-tension
B)translocation
C)pressure flow
D)osmosis
E)transpiration

Question 78

When solutes are unloaded from phloem, water ____.

A)is pumped into the phloem by active transport
B)leaves the xylem by osmosis
C)moves into the phloem by facilitated diffusion
D)is pumped out of the phloem by active transport
E)leaves the phloem by osmosis

Question 80

Companion cells load most of the carbohydrates into sieve tube members ____.

A)through plasmodesmata
B)by osmosis
C)by antiport
D)through carrier proteins
E)by symport