Question 1

In which plant cell or tissue would the pressure component of water potential most often be negative?

Accepted Answer

A)   stem xylem
B)   stem phloem
C)   root epidermis
D)   root cortex cell
E)   leaf mesophyll cell

Question 2

Water potential in plants consists mainly of

Accepted Answer

A)   pressure potential and membrane potential.
B)   pressure potential and solute potential.
C)   solute potential only.
D)   solute potential and membrane potential.
E)   solute potential and osmotic potential.

Question 3

Which theory of water transport in xylem can also be used to explain the movement of water in nonvascular plants such as mosses?

Accepted Answer

A)   proton pump
B)   capillarity
C)   root pressure
D)   pressure flow
E)   cohesion- tension

Question 4

If you cut a stalk petiole)  of celery and place it in a beaker of water that has food colouring dissolved in it, coloured water will move up the stalk and into the leaf blades. This provides evidence against which of the following theories of xylem transport?

Accepted Answer

A)   cohesion- tension
B)   root pressure
C)   proton pump
D)   capillarity
E)   pressure flow

Question 5

Which of the following observations provides the strongest evidence against root pressure being the principal mechanism of water transport in the xylem?

Accepted Answer

A)   A water potential gradient between roots and shoots.
B)   The movement of water into the xylem from surrounding cells in the roots.
C)   Not all plants have roots.
D)   Not all soils have high concentrations of ions.
E)   Shoots with roots removed can transport water when placed in a container of water.

Question 6

Which of the following cross- membrane transport mechanisms requires the expenditure of energy?

Accepted Answer

A)   channel
B)   facilitated diffusion
C)   carrier
D)   symporter
E)   direct diffusion

Question 7

Loss of water from the aerial parts of plants is called

Accepted Answer

A)   cohesion- tension.
B)   transpiration.
C)   pressure flow.
D)   evaporation.
E)   respiration.

Question 8

The processes of water flow in xylem and sugar translocation in phloem differ in many respects. Which of the following is not a difference between xylem and phloem transport?

Accepted Answer

A)   Xylem transport always occurs in the same direction; phloem transport does not.
B)   Xylem transport is a wholly passive process; phloem transport includes active energy- requiring)  processes.
C)   Water potential gradients are required for xylem transport to occur, but not for phloem transport.
D)   Cells through which xylem transport occurs are "dead" at maturity; those in phloem transport are "alive."

Question 9

What drives the flow of water through the xylem?

Accepted Answer

A)   passive transport by the endodermis
B)   the evaporation of water from the leaves
C)   active transport by parenchyma cells within xylem tissue
D)   the number of companion cells in the phloem
E)   active transport by tracheid and vessel elements

Question 10

Which of the following cross- membrane transport mechanisms occur without expenditure of energy?

Accepted Answer

A)   antiporter
B)   channel
C)   cotransporter
D)   pump
E)   symporter

Question 11

Cell- to- cell water movement always occurs from

Accepted Answer

A)   lower to higher water potential.
B)   higher to lower water potential.
C)   lower to higher solute potential.
D)   higher to lower solute potential.
E)   higher to lower pressure potential.

Question 12

Which of the following structural features of plants would not be expected to reduce transpiration?

Accepted Answer

A)   thick cuticle on leaves and stems
B)   reduced leaf size
C)   stomata on upper and lower surfaces of the leaves
D)   sunken stomata
E)   abundant epidermal hairs on leaves and stems

Question 13

Which of the following statements about phloem unloading at sinks is not consistent with our current understanding?

Accepted Answer

A)   Active and passive transport play a role.
B)   The mechanisms of sucrose movement and the membrane proteins involved vary among different plant species.
C)   Regardless of the type of sink, the conversion of sucrose to storage compounds, such as starch, is a major part of the process.
D)   Water moves by osmosis from phloem to xylem.
E)   The mechanisms of sucrose movement and the membrane proteins involved vary among different sinks within a plant.

Question 14

J. A. Milburn and R. P. C. Johnson developed an acoustic method for detecting cavitation formation of air bubbles)  in plants. This involves "listening" for characteristic clicks produced during air- bubble formation, using sensitive microphones and amplifiers. In one experiment with the castor bean plant Ricinus communis) , they detached leaves by cutting the petioles and subjected them to various treatments. Which of the following would be least likely to be observed in such an experiment?

Accepted Answer

A)   as the leaf is allowed to wilt, recording many clicks that approximately equal the estimated number of vessels in the cut petiole
B)   after adding water to the cut end of the petiole, recording an increased rate of clicking
C)   after increasing transpiration by blowing warm air across the leaf, recording an increased rate of clicking

Question 15

Root pressure can result in the early morning appearance of water droplets on leaves and flowers of low- growing plants. Which of the following does not contribute to the development of root pressure?

Accepted Answer

A)   creation of a water potential gradient between the xylem lower ƒ)  and surrounding cells higher ƒ)  in the root
B)   movement of ions from epidermis to xylem
C)   closed stomata
D)   accumulation of ions from the soil by root epidermal cells
E)   creation of tension in the xylem water column that leads to short- distance water movement

Question 16

As an undergraduate research assistant, you are assisting with a radioisotope tracer experiment. You expose a mature leaf on one side of the lower shoot of a sugar beet plant to 14CO2 and then track the movement of the 14C atoms by radiography. Where are you least likely to detect 14C?

Accepted Answer

A)   the shoot apical meristem
B)   a young leaf directly above the treated leaf
C)   a mature upper leaf on the opposite side of the plant from the treated leaf
D)   the treated leaf
E)   the roots

Question 17

How does a flaccid cell differ from a turgid cell?

Accepted Answer

A)   Flaccid cell has lower pressure potential.
B)   Flaccid cell has lower solute potential.
C)   Flaccid cell has higher pressure potential.
D)   Flaccid cell has higher solute potential.

Question 18

Which of the following adaptations are least likely to be found in plants that regularly experience dry, hot conditions?

Accepted Answer

A)   a thick cuticle on fleshy leaves
B)   plants that do not produce abscisic acid and have a short, thick taproot
C)   CAM plants that grow rapidly
D)   large, fleshy stems with the ability to carry out photosynthesis
E)   small, thick leaves with stomata on the lower surface

Question 19

CAM plants perform photosynthesis during the day even though their stomata are closed. How do these plants obtain carbon dioxide in order to carry out photosynthesis?

Accepted Answer

A)   CAM plants use glucose as their main source of carbon dioxide during periods of drought.
B)   CAM plants transport carbon dioxide from the soil through the phloem to offset the loss of carbon dioxide uptake in the leaves.
C)   Carbon dioxide is stored within specialized bundle sheath cells during mild temperatures for use during drought.
D)   CAM plants open their stomata at night to obtain carbon dioxide.

Question 20

The research by Natalie De Witt and Michael Sussman showed that proton pump AHA3 is localized in the membrane of companion cells of the source tissue. What is the function of this pump?

Accepted Answer

A)   to move protons from inside of a companion cell to a source cell
B)   to move protons and sucrose from outside of a companion cell to inside
C)   to move protons and sucrose from inside of a companion cell to outside
D)   to move protons from inside of a companion cell to outside
E)   to move protons from outside of a companion cell to inside

Exam 35: Water and Sugar Transport in Plants

Which of the following statements about phloem unloading at sinks is not consistent with our current understanding?

Correct Answer
verified

Which of the following observations provides the strongest evidence against root pressure being the principal mechanism of water transport in the xylem?

Correct Answer
verified

What drives the flow of water through the xylem?

Correct Answer
verified

How does a flaccid cell differ from a turgid cell?

Correct Answer
verified

Loss of water from the aerial parts of plants is called

Correct Answer
verified

Which of the following cross- membrane transport mechanisms requires the expenditure of energy?

Correct Answer
verified

The processes of water flow in xylem and sugar translocation in phloem differ in many respects. Which of the following is not a difference between xylem and phloem transport?

Correct Answer
verified

The research by Natalie De Witt and Michael Sussman showed that proton pump AHA3 is localized in the membrane of companion cells of the source tissue. What is the function of this pump?

Correct Answer
verified

CAM plants perform photosynthesis during the day even though their stomata are closed. How do these plants obtain carbon dioxide in order to carry out photosynthesis?

Correct Answer
verified

Correct Answer
verified

Which of the following cross- membrane transport mechanisms occur without expenditure of energy?

Correct Answer
verified

Which theory of water transport in xylem can also be used to explain the movement of water in nonvascular plants such as mosses?

Correct Answer
verified

Cell- to- cell water movement always occurs from

Correct Answer
verified

Water potential in plants consists mainly of

Correct Answer
verified

Root pressure can result in the early morning appearance of water droplets on leaves and flowers of low- growing plants. Which of the following does not contribute to the development of root pressure?

Correct Answer
verified

As an undergraduate research assistant, you are assisting with a radioisotope tracer experiment. You expose a mature leaf on one side of the lower shoot of a sugar beet plant to ¹⁴CO₂and then track the movement of the¹⁴C atoms by radiography. Where are you least likely to detect ¹⁴C?

Correct Answer
verified

Which of the following adaptations are least likely to be found in plants that regularly experience dry, hot conditions?

Correct Answer
verified

If you cut a stalk petiole) of celery and place it in a beaker of water that has food colouring dissolved in it, coloured water will move up the stalk and into the leaf blades. This provides evidence against which of the following theories of xylem transport?

Correct Answer
verified

Which of the following structural features of plants would not be expected to reduce transpiration?

Correct Answer
verified

In which plant cell or tissue would the pressure component of water potential most often be negative?

Correct Answer
verified

Exam 35: Water and Sugar Transport in Plants

Which of the following statements about phloem unloading at sinks is not consistent with our current understanding?

Correct AnswerverifiedShow Answer

Which of the following observations provides the strongest evidence against root pressure being the principal mechanism of water transport in the xylem?

Correct AnswerverifiedShow Answer

What drives the flow of water through the xylem?

Correct AnswerverifiedShow Answer

How does a flaccid cell differ from a turgid cell?

Correct AnswerverifiedShow Answer

Loss of water from the aerial parts of plants is called

Correct AnswerverifiedShow Answer

Which of the following cross- membrane transport mechanisms requires the expenditure of energy?

Correct AnswerverifiedShow Answer

The processes of water flow in xylem and sugar translocation in phloem differ in many respects. Which of the following is not a difference between xylem and phloem transport?

Correct AnswerverifiedShow Answer

The research by Natalie De Witt and Michael Sussman showed that proton pump AHA3 is localized in the membrane of companion cells of the source tissue. What is the function of this pump?

Correct AnswerverifiedShow Answer

CAM plants perform photosynthesis during the day even though their stomata are closed. How do these plants obtain carbon dioxide in order to carry out photosynthesis?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Which of the following cross- membrane transport mechanisms occur without expenditure of energy?

Correct AnswerverifiedShow Answer

Which theory of water transport in xylem can also be used to explain the movement of water in nonvascular plants such as mosses?

Correct AnswerverifiedShow Answer

Cell- to- cell water movement always occurs from

Correct AnswerverifiedShow Answer

Water potential in plants consists mainly of

Correct AnswerverifiedShow Answer

Root pressure can result in the early morning appearance of water droplets on leaves and flowers of low- growing plants. Which of the following does not contribute to the development of root pressure?

Correct AnswerverifiedShow Answer

As an undergraduate research assistant, you are assisting with a radioisotope tracer experiment. You expose a mature leaf on one side of the lower shoot of a sugar beet plant to 14CO2 and then track the movement of the 14C atoms by radiography. Where are you least likely to detect 14C?

Correct AnswerverifiedShow Answer

Which of the following adaptations are least likely to be found in plants that regularly experience dry, hot conditions?

Correct AnswerverifiedShow Answer

If you cut a stalk petiole) of celery and place it in a beaker of water that has food colouring dissolved in it, coloured water will move up the stalk and into the leaf blades. This provides evidence against which of the following theories of xylem transport?

Correct AnswerverifiedShow Answer

Which of the following structural features of plants would not be expected to reduce transpiration?

Correct AnswerverifiedShow Answer

In which plant cell or tissue would the pressure component of water potential most often be negative?

Correct AnswerverifiedShow Answer

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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
verified

As an undergraduate research assistant, you are assisting with a radioisotope tracer experiment. You expose a mature leaf on one side of the lower shoot of a sugar beet plant to ¹⁴CO₂and then track the movement of the¹⁴C atoms by radiography. Where are you least likely to detect ¹⁴C?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified