Question 1

When an animal cell is placed in a hypotonic solution and water enters the cell via osmosis, the volume of the cell increases until it bursts. This does not happen to plant cells, because ________.

Accepted Answer

A)  they have large central vacuoles, which provide abundant space for storage of incoming water 
B)  they have cell walls, which prevent the entry of water by osmosis 
C)  they have cell walls, which provide pressure to counteract the pressure of the incoming water 
D)  certain gated channel proteins embedded in their plasma membranes open as osmotic pressure decreases, allowing excess water to leave the cell

Question 2

The physical property that predicts the direction of water flow is referred as ________.

Accepted Answer

A)  potassium pump 
B)  water potential 
C)  osmotic potential 
D)  sodium pump

Question 3

During the nighttime, due to lack of transpiration, the water potential within the vascular cylinder ________.

Accepted Answer

A)  lowers due to accumulation of minerals 
B)  increases due to accumulation of minerals 
C)  lowers due to loss of minerals 
D)  increases due to loss of minerals

Question 4

The high surface-to-volume ratio in leaves aids in ________.

Accepted Answer

A)  more light absorption 
B)  less light absorption 
C)  CO₂ absorption 
D)  transpiration

Question 5

Which of the following primarily enters a plant somewhere other than through the roots?

Accepted Answer

A)  carbon dioxide 
B)  nitrogen 
C)  potassium 
D)  water

Question 6

Bulk flow is much faster than diffusion or active transport. Peak velocities in the transport of xylem sap can range from ________ for trees with wide vessel elements.

Accepted Answer

A)  10-20 m/hr 
B)  15-45 m/hr 
C)  5-10 m/hr 
D)  >50 m/hr

Question 7

Which one of the following ions plays a critical role in the opening and closing of stomata?

Accepted Answer

A)  H⁺ 
B)  Na⁺ 
C)  K⁺ 
D)  Ca⁺²

Question 8

What is the advantage of having small, needlelike leaves?

Accepted Answer

A)  increased transpiration rate 
B)  decreased transpiration rate 
C)  increased efficiency of light capture 
D)  decreased efficiency of light capture

Question 9

The apoplast in plant tissues consists of ________.

Accepted Answer

A)  cell walls, extracellular spaces, and plasmodesmata 
B)  cell walls, extracellular spaces, and vessel elements 
C)  vessel elements, plasmodesmata, and extracellular spaces 
D)  cell walls, plasma membrane, and cytosol

Question 10

If ΨP = 0.3 MPa and ΨS = -0.45 MPa, the resulting Ψ is ________.

Accepted Answer

A)  +0.75 MPa 
B)  -0.75 MPa 
C)  -0.15 MPa 
D)  +0.15 MPa

Question 11

How does a flaccid cell differ from a turgid cell?

Accepted Answer

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

Question 12

Compared to a cell with few aquaporins in its membrane, a cell containing many aquaporins will ________.

Accepted Answer

A)  have a faster rate of osmosis 
B)  have a lower water potential 
C)  have a higher water potential 
D)  have a faster rate of active transport

Question 13

Which structure or compartment is part of the symplast?

Accepted Answer

A)  the interior of a vessel element 
B)  the interior of a sieve tube 
C)  the cell wall of a mesophyll cell 
D)  an extracellular air space

Question 14

Which structure or compartment is separate from the apoplastic route?

Accepted Answer

A)  the lumen of a xylem vessel 
B)  the lumen of a sieve tube 
C)  the cell wall of a mesophyll cell 
D)  the cell wall of a root hair

Question 15

Which of the following supports the finding that sugar translocation in phloem is an active (energy-requiring)process?

Accepted Answer

A)  Sucrose occurs in higher concentrations in companion cells than in the mesophyll cells where it is produced. 
B)  Movement of water occurs from xylem to phloem and back again. 
C)  Strong pH differences exist between the cytoplasm of the companion cell and the mesophyll cell. 
D)  ATPases are abundant in the plasma membranes of the mesophyll cells.

Question 16

Formation of the curved upper surface, such as occurs in a tube filled with water, is an important factor in plant water movement. A curved upper surface is created by ________.

Accepted Answer

A)  the upward pull of gravity on the water column in the tube 
B)  downward pressure from the atmosphere on the topmost layer of water molecules 
C)  the water molecules being pulled upward by adhesion to the air 
D)  the topmost layer of water molecules being pulled downward by the hydrogen bonds to the water molecules below

Question 17

If you place flaccid plant cells in pure water, water ________ into cell because it has ________.

Accepted Answer

A)  does not enter the cell; solutes and low water potential 
B)  enter the cell; solutes and low water potential 
C)  enter the cell; solutes and high water potential 
D)  does not enter the cell; solutes and high water potential

Question 18

The value for Ψ in root tissue was found to be -0.15 MPa. If you take the root tissue and place it in a 0.1 M solution of sucrose (Ψ = -0.23 MPa), the net water flow would ________.

Accepted Answer

A)  be from the tissue into the sucrose solution 
B)  be from the sucrose solution into the tissue 
C)  be in both directions and the concentrations would remain equal 
D)  occur only as ATP was hydrolyzed in the tissue

Question 19

A water molecule could move all the way through a plant from soil to root to leaf to air and pass through a living cell only once. This living cell would be a part of which structure?

Accepted Answer

A)  a guard cell 
B)  the root epidermis 
C)  the endodermis 
D)  the root cortex

Question 20

Plants adapted to arid environments are referred to as ________.

Accepted Answer

A)  mesophytes 
B)  xerophytes 
C)  psilophytes 
D)  halophytes

Exam 36: Resource Acquisition and Transport in Vascular Plants