Ch. 38 Questions Flashcards
Active transport of amino acids in plants at the cellular level requires _____.
a. ATP, transport proteins & a protein gradient
b. sodium / potassium pumps & xylem membranes
c. xylem membranes & channel proteins
d. NADP & channel proteins
a. ATP, transport proteins & a protein gradient
Which of the following transmembrane transport mechanism requires the expenditure of energy?
a. aquaporins
b. channel
c. facilitated diffusion
d. antiporter
d. antiporter
According to the pressure-flow hypothesis of phloem transport, _____.
a. solute moves from a high concentration in the source to a lower concentration in the sink
b. the pressure of the phloem of a root is normally greater than the pressure in the phloem of a leaf
c. the formation of starch from sugar in the sink increases the osmotic concentration
d. the combination of high turgor pressure in the source & transpiration water loss from the sink moves solutes through phloem conduits
e. water is actively transported into the source region of the phloem to create the turgor pressure needed
a. solute moves from a high concentration in the source to a lower concentration in the sink
Which one of the following statements about transport of nutrients in phloem is correct?
a. differences in osmotic concentration at the source & sink cause a hydrostatic pressure gradient to be formed
b. companion cells control the rate & direction of movement of phloem sap
c. a sink is the part of a plant where a particular solute is produced
d. solute particles are actively transported from phloem at the source
a. differences in osmotic concentration at the source & sink cause a hydrostatic pressure gradient to be formed
Which structure or compartment is part of the symplast?
a. the cell wall of a mesophyll cell
b. the interior of a sieve tube
c. the interior of a vessel element
d. the cell wall of a root hair
e. an extracellular air space
b. the interior of a sieve tube
CAM & C4 plants conduct photosynthesis in ways that allow them to live in drier areas than most C3 plants can tolerate. The effectiveness of different plants in restricting water loss while still allowing for influx of adequate carbon dioxide can be compared using the transpiration ratio, which is calculated by dividing the amount of water transpired by the amount of carbon dioxide fixed by photosynthesis. If a typical transpiration ratio for a C3 plant is 500, then possible values for CAM & C4 plants could be ______.
a. 500
b. 750-100
c. 50-250
c. 50-250
Water potential is generally most negative in which of the following parts of a plant?
a. mesophyll cells of the leaf
b. root hairs
c. xylem vessels in leaves
d. cells of the root cortex
e. xylem vessels in roots
a. mesophyll cells of the leaf
Arrange the following five events in an order that explains the mass flow of materials in the phloem.
- water diffuses into the sieve tubes
- leaf cells produce sugar by photosynthesis
- solutes are actively transported into sieve tubes
- sugar is transported from cell to cell in the leaf
- sugar moves down the stem
- leaf cells produce sugar by photosynthesis
- sugar is transported from cell to cell in the leaf
- solutes are actively transported into sieve tubes
- water diffuses into the sieve tubes
- sugar moves down the stem
Active transport would be LEAST important in the normal functioning of which of the following plant tissue types?
a. stem tracheids
b. leaf transfer cells
c. root sieve-tube elements
d. leaf mesophyll cells
e. root endodermal cells
a. stem tracheids
In which plant cell or tissue would the pressure component of water potential most often be negative?
a. root epidermis
b. stem xylem
c. stem phloem
d. leaf mesophyll cell
e. root cortex cell
a. stem tracheids
The following factors may sometimes play a role in the movement of sap through xylem. Which one depends on the direct expenditure of ATP by the plant?
a. bulk flow of water in the root apoplast
b. capillarity movement of water within the xylem
c. concentration of ions in the symplast
d. cohesion among water molecules
e. evaporation of water from leaves
c. concentration of ions in the symplast
