Which of the following are long, thin cells that
overlap, are tapered end to end, and carry water?
a. parenchyma
b. sieve tube members
c. tracheids
d. companion cells
e. phloem
Answer: c
Which of the following results from the direct
expenditure of energy in a plant?
a. root pressure
b. evaporation of water from the leaves
c. water flowing into the root apoplast
d. transpirational flow
e. sap flowing down from the leaves to the roots
Answer: e
The rate of flow of water through the xylem is
regulated by
a. passive transport in the pith.
b. the force of transpirational pull.
c. active transport by the sieve-tube members.
d. the number of companion cells in the phloem.
e. active transport by tracheid and vessel cells.
Answer: b
The driving force for the movement of materials
in the phloem of plants is
a. gravity.
b. a difference in osmotic pressure between the
source and sink.
c. root pressure.
d. transpiration of water through the stomata.
e. adhesion of water to vessel elements.
Answer: b
Which of the following has the lowest water
potential?
a. root xylem
b. stem xylem
c. soil
d. air spaces in the leaf
e. root hairs
Answer: d
   s  p
   s  p
Bulk flow:
Movement due
to pressure
(tension)
Which of the following are long, thin cells that
overlap, are tapered end to end, and carry water?
a. parenchyma
b. sieve tube members
c. tracheids
d. companion cells
e. phloem
Answer: c
Which of the following results from the direct
expenditure of energy in a plant?
a. root pressure
b. evaporation of water from the leaves
c. water flowing into the root apoplast
d. transpirational flow
e. sap flowing down from the leaves to the roots
Answer: e
The rate of flow of water through the xylem is
regulated by
a. passive transport in the pith.
b. the force of transpirational pull.
c. active transport by the sieve-tube members.
d. the number of companion cells in the phloem.
e. active transport by tracheid and vessel cells.
Answer: b
The driving force for the movement of materials
in the phloem of plants is
a. gravity.
b. a difference in osmotic pressure between the
source and sink.
c. root pressure.
d. transpiration of water through the stomata.
e. adhesion of water to vessel elements.
Answer: b
Which of the following has the lowest water
potential?
a. root xylem
b. stem xylem
c. soil
d. air spaces in the leaf
e. root hairs
Answer: d