Question 1

Root hairs are most important to a plant because they ________.

Accepted Answer

A)  anchor a plant in the soil 
B)  store starches 
C)  increase the surface area for absorption 
D)  provide a habitat for nitrogen-fixing bacteria 
E)  contain xylem tissue 
A)  anchor a plant in the soil 
B)  store starches 
C)  increase the surface area for absorption 
D)  provide a habitat for nitrogen-fixing bacteria 
E)  contain xylem tissue

Question 2

The water lost during transpiration is a side effect of the plant's exchange of gases. However, the plant derives some benefit from this water loss in the form of ________.

Accepted Answer

A)  increased turgor and increased growth 
B)  sucrose transport and increased growth 
C)  evaporative cooling and increased turgor 
D)  evaporative cooling and mineral transport 
A)  increased turgor and increased growth 
B)  sucrose transport and increased growth 
C)  evaporative cooling and increased turgor 
D)  evaporative cooling and mineral transport

Question 3

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

Accepted Answer

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

Question 4

Water potential (ψ) can be thought of as the tendency for water to move from one place to another. In plants, it is made up mainly of solute potential and pressure potential. Hypothetical plant cells A and B are adjacent to each other. The solute potential (ψS) of cell A is −0.35 MPa, and its pressure potential (ψP) is +0.15 MPa. The solute potential (ψS) of cell B is −0.30 MPa, and its pressure potential (ψP) is +0.05 MPa. In which direction will net water movement occur?

Accepted Answer

A)  neither; cells A and B are in equilibrium with each other. 
B)  from cell A to cell B 
C)  from cell B to cell A 
A)  neither; cells A and B are in equilibrium with each other. 
B)  from cell A to cell B 
C)  from cell B to cell A

Question 5

What would enhance water uptake by a plant cell?

Accepted Answer

A)  decreasing the Ψ of the surrounding solution 
B)  increasing the pressure exerted by the cell wall 
C)  the loss of solutes from the cell 
D)  increasing the Ψ of the cytoplasm 
E)  positive pressure on the surrounding solution 
A)  decreasing the Ψ of the surrounding solution 
B)  increasing the pressure exerted by the cell wall 
C)  the loss of solutes from the cell 
D)  increasing the Ψ of the cytoplasm 
E)  positive pressure on the surrounding solution

Question 6

The research by Michael Sussman showed that a gene called SUC2 is expressed in vascular tissue, encoding a proton-sucrose symporter. Mutant plants lacking a functional SUC2 gene were unable to ________.

Accepted Answer

A)  export sugar from mesophyll cells to the rest of the plant 
B)  accumulate starch in plant chloroplasts 
C)  load sucrose into mesophyll cells 
D)  carry out facilitated diffusion 
A)  export sugar from mesophyll cells to the rest of the plant 
B)  accumulate starch in plant chloroplasts 
C)  load sucrose into mesophyll cells 
D)  carry out facilitated diffusion

Question 7

If isolated plant cells with a water potential averaging −0.5 MPa are placed into a solution with a water potential of −0.3 MPa, which of the following would be the most likely outcome?

Accepted Answer

A)  The pressure potential of the cells would increase. 
B)  Water would move out of the cells. 
C)  The cell walls would rupture, killing the cells. 
D)  Solutes would move out of the cells. 
E)  The osmotic pressure of the cells would decrease. 
A)  The pressure potential of the cells would increase. 
B)  Water would move out of the cells. 
C)  The cell walls would rupture, killing the cells. 
D)  Solutes would move out of the cells. 
E)  The osmotic pressure of the cells would decrease.

Exam 35: Water and Sugar Transport in Plants

Root hairs are most important to a plant because they ________.

The water lost during transpiration is a side effect of the plant's exchange of gases. However, the plant derives some benefit from this water loss in the form of ________.

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

What would enhance water uptake by a plant cell?

The research by Michael Sussman showed that a gene called SUC2 is expressed in vascular tissue, encoding a proton-sucrose symporter. Mutant plants lacking a functional SUC2 gene were unable to ________.

If isolated plant cells with a water potential averaging −0.5 MPa are placed into a solution with a water potential of −0.3 MPa, which of the following would be the most likely outcome?

Biology and the Tree of Life

Water and Carbon: the Chemical Basis of Life

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Nucleic Acids and the Rna World

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