Deck 34: Transport in Plants

Question 1

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

Answer 1

D

Question 2

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 2

C

Question 3

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

Answer 3

A

Question 4

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

Question 5

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

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

Question 6

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

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

Question 7

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 8

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 9

Phloem does not transport ____.

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

Question 10

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

A) 300
B) 1,000
C) 1,400
D) 2,000
E) 2,400

Question 11

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 12

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 13

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 14

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 15

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

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

Question 16

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

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

Question 17

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 18

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 19

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) α
B) γ
C) ψ
D) π
E) θ

Question 20

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 21

What is the ψP of a living plant cell that has ψ = -0.2 MPa and ψS = -0.4 MPa?

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

Question 22

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

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

Question 23

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

A) take up water until it bursts
B) lose water until its ψ = ψ of the solution
C) take up water until within the cell ψP = 0
D) take up water until its ψ = ψS of the solution
E) lose water until its ψS = its ψP

Question 24

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 25

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 26

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 27

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

A) take up water until it bursts
B) lose water until its ψ = ψ of the solution
C) take up water until within the cell ψP = -ψS
D) take up water until its ψ = ψS of the solution
E) lose water until its ψS = its ψP

Question 28

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 29

Active transport in plant root cells requires that those cells have access to O₂. Normally there is enough O₂available 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 30

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

A) within the cell ψP = -ψS
B) it bursts
C) its ψP = 0
D) its ψS = ψS of the pure water
E) its ψS = 0

Question 31

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 32

If the ψ 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 33

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 34

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

A) take up water until it bursts
B) lose water until its ψ = ψ of the solution
C) take up water until within the cell ψP = -ψS
D) take up water until its ψ = ψS of the solution
E) lose water until its ψS = its ψP

Question 35

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 36

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 37

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

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

Question 38

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 ψP = 0.3 MPa and ψS = -0.5 MPa, while the other cell has ψS = -0.3 MPa. What is the ψP of the second cell?

A) ψP = -0.8 MPa
B) ψP = 0 MPa
C) ψP = 0.5 MPa
D) ψP = 0.8 MPa
E) ψP = 0.1 MPa

Question 39

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 40

The ____ prevent(s) important substances in the xylem from leaking into the root cortex.

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

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 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 43

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 44

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 45

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 46

Stomata generally open in response to ____.

A) the release of abscisic acid by the roots
B) a drop in CO₂concentration in leaf air spaces
C) exposure to red light
D) a drop in O₂concentration in leaf air spaces
E) an increase in CO₂concentration in the leaf air spaces

Question 47

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

A) sunlight
B) ion concentrations in the xylem
C) CO₂concentration
D) O₂concentration
E) abscisic acid

Question 48

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 49

Stomata generally close in response to ____.

A) the release of abscisic acid by the roots
B) a drop in CO₂concentration in leaf air spaces
C) exposure to red light
D) a drop in O₂concentration in leaf air spaces
E) an increase in CO₂concentration in the leaf air spaces

Question 50

Experiments have shown that xylem sap transport peaks ____.

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

Question 51

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 52

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 53

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 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

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 56

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 57

A plant stoma is found between two ____.

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

Question 58

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 59

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 60

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 61

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 62

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 63

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 64

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 65

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 66

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

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

Question 67

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 69

"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 70

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 71

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 72

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 73

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 74

The living portion of the pathway through which water travels through a root is called the apoplastic pathway.

Question 75

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 76

Phloem sap would not be expected to contain ____.

A) carbohydrates
B) hormones
C) water
D) amino acids
E) lipids

Question 77

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 78

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

Question 79

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 80

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

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