Campbell’s Biology, 9e (Reece et al.)
Chapter 36 Resource Acquisition and Transport in Vascular Plants
This chapter is often one of the most difficult for students to master because it draws upon the
information in several previous chapters, as well as basic concepts in chemistry and physics, to explain
water potential and the movement of nutrients and water in plants. The coordination and
interdependency of cells, tissues, organs, and systems in transport are stressed as well as the importance
of maintaining water balance while allowing for sufficient gas exchange to maximize carbon acquisition.
Multiple-Choice Questions
1) All of the following are plant adaptations to life on land except
A) tracheids and vessels.
B) root hairs.
C) cuticle.
D) the Calvin cycle of photosynthesis.
E) collenchyma.
2) The ancestors of land plants were aquatic algae. Which of the following is not an evolutionary
adaptation to life on land?
A) C3 photosynthesis
B) a waxy cuticle
C) root hairs
D) xylem and phloem
E) guard cells
3) Most angiosperms have alternate phyllotaxy. What allows each leaf to get the maximum exposure to
light and reduces shading of lower leaves?
A) a leaf area index above 8
B) self-pruning
C) one leaf only per node
D) leaf emergence at an angle of 137.5°F from the site of previous leaves
E) a leaf area index above 8 and leaf emergence at an angle of 137.5°F from the site of previous leaves
4) A plant developed a mineral deficiency after being treated with a fungicide. What is the most
probable cause of the deficiency?
A) Mineral receptor proteins in the plant membrane were not functioning.
B) Mycorrhizal fungi were killed.
C) Active transport of minerals was inhibited.
D) The genes for the synthesis of transport proteins were destroyed.
E) Proton pumps reversed the membrane potential.
5) If you were to prune the shoot tips of a plant, what would be the effect on the plant and the leaf area
index?
A) bushier plants; lower leaf area index
B) tall plants; lower leaf area index
C) tall plants; higher leaf area index
D) short plants; lower leaf area index
E) bushier plants; higher leaf area indexes
6) Which structure or compartment is not part of the plant’s apoplast?
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 transfer cell
E) the cell wall of a root hair
7) Which of the following would be least likely to affect osmosis in plants?
A) proton pumps in the membrane
B) a difference in solute concentrations
C) receptor proteins in the membrane
D) aquaporins
E) a difference in water potential
8) Active transport involves all of the following except the
A) diffusion of solute through the lipid bilayer of a membrane.
B) pumping of solutes across the membrane.
C) hydrolysis of ATP.
D) transport of solute against a concentration gradient.
E) specific transport protein in the membrane.
9) Active transport of various materials in plants at the cellular level requires all of the following except
A) a proton gradient.
B) ATP.
C) membrane potential.
D) transport proteins
E) xylem membranes.
10) Which of the following is not a function of the plasma membrane proton pump?
A) hydrolyzes ATP
B) produces a proton gradient
C) generates a membrane potential
D) equalizes the charge on each side of a membrane
E) stores potential energy on one side of a membrane
11) Given that early land plants most likely share a common ancestor with green algae, the earliest land
plants were most likely
A) nonvascular plants that grew leafless photosynthetic shoots above the shallow fresh water in which
they lived.
B) species that did not exhibit alternation of generations.
C) vascular plants with well-defined root systems.
D) plants with well-developed leaves.
E) species with a well-developed, thick cuticle.
12) The movement of water across biological membranes can best be predicted by
A) negative charges in the cell wall.
B) prevailing weather conditions.
C) aquaporins.
D) level of active transport.
E) water potential.
13) An open beaker of pure water has a water potential (Ψ) of
A) -0.23 MPa.
B) +0.23 MPa.
C) +0.07 MPa.
D) -0.0000001 MPa.
E) 0.0 (zero).
14) All of the following have an effect on water potential (Ψ) in plants except
A) physical pressure.
B) water-attracting matrices.
C) dissolved solutes.
D) osmosis.
E) DNA structure.
15) If ΨP = 0.3 MPa and ΨS = –0.45 MPa, the resulting Ψ is
A) +0.75 MPa.
B) -0.75 MPa.
C) -0.15 MPa.
D) +0.15 MPa.
E) -0.42 MPa.
16) 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
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.
E) be impossible to determine from the values given here.
17) Compared to a cell with few aquaporins in its membrane, a cell containing many aquaporins will
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.
E) be flaccid.
18) Some botanists argue that the entire plant should be considered as a single unit rather than a
composite of many individual cells. Which of the following cellular structures cannot be used to support
this view?
A) cell wall
B) cell membrane
C) cytosol
D) tonoplast
E) symplast
19) Which of the following statements is false about bulk flow?
A) It is driven primarily by pressure potential.
B) It is more effective than diffusion over distances greater than 100 μm.
C) It depends on a difference in pressure potential at the source and sink.
D) It depends on the force of gravity on a column of water.
E) It may be the result of either positive or negative pressure potential.
20) Which of the following would likely not contribute to the surface area available for water absorption
from the soil by a plant root system?
A) root hairs
B) endodermis
C) mycorrhizae
D) fungi associated with the roots
E) fibrous arrangement of the roots
21) Root hairs are most important to a plant because they
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.
22) 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?
A) the Casparian strip
B) a guard cell
C) the root epidermis
D) the endodermis
E) the root cortex
23) All of the following involve active transport across membranes except
A) the movement of mineral nutrients from the apoplast to the symplast.
B) the movement of sugar from mesophyll cells into sieve-tube elements.
C) the movement of sugar from one sieve-tube element to the next.
D) the movement of K+ across guard cell membranes during stomatal opening.
E) the movement of mineral nutrients into cells of the root cortex.
24) Which of the following statements about xylem is incorrect?
A) It conducts material from root tips to leaves.
B) The conducting cells are part of the apoplast.
C) It transports mainly sugars and amino acids.
D) It typically has a lower water potential than is found in soil.
E) No energy input is required for transport.
25) What is the role of proton pumps in root hair cells?
A) establish ATP gradients
B) maintain the H+ gradient
C) pressurize xylem transport
D) eliminate excess electrons
E) assist in active uptake of water molecules
26) In plant roots, the Casparian strip is correctly described by which of the following?
A) It aids in the uptake of nutrients.
B) It provides energy for the active transport of minerals into the stele from the cortex.
C) It ensures that all minerals are absorbed from the soil in equal amounts.
D) It ensures that all water and dissolved substances must pass through a cell membrane before entering
the stele.
E) It provides increased surface area for the absorption of mineral nutrients.
27) Which of the following is not an important component of the long-distance transport process in
plants?
A) the cohesion of water molecules
B) a negative water potential
C) the root parenchyma
D) the active transport of solutes
E) bulk flow from source to sink
28) Pine seedlings grown in sterile potting soil grow much slower than seedlings grown in soil from the
area where the seeds were collected. This is most likely because
A) the sterilization process kills the root hairs as they emerge from the seedling.
B) the normal symbiotic fungi are not present in the sterilized soil.
C) sterilization removes essential nutrients from the soil.
D) water and mineral uptake is faster when mycorrhizae are present.
E) B and D.
29) 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) capillarity of water within the xylem
B) evaporation of water from leaves
C) cohesion among water molecules
D) concentration of ions in the symplast
E) bulk flow of water in the root apoplast
30) One is most likely to see guttation in small plants when the
A) transpiration rates are high.
B) root pressure exceeds transpiration pull.
C) preceding evening was hot, windy, and dry.
D) water potential in the stele of the root is high.
E) roots are not absorbing minerals from the soil.
31) One would expect to find the highest density of aquaporins in which of the following?
A) the plasma membrane of guard cells
B) the pits of a tracheid
C) the plasma membrane of parenchyma cells in a ripe fruit
D) the plasma membrane of a mature mesophyll cell in a leaf
E) the membrane lining plasmodesmata
32) 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?
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.
33) What drives the flow of water through the xylem?
A) passive transport by the endodermis
B) the number of companion cells in the phloem
C) the evaporation of water from the leaves
D) active transport by sieve-tube elements
E) active transport by tracheid and vessel elements
34) What is the main force by which most of the water within xylem vessels moves toward the top of a
tree?
A) active transport of ions into the stele
B) atmospheric pressure on roots
C) evaporation of water through stoma
D) the force of root pressure
E) osmosis in the root
35) In which plant cell or tissue would the pressure component of water potential most often be
negative?
A) leaf mesophyll cell
B) stem xylem
C) stem phloem
D) root cortex cell
E) root epidermis
36) Water potential is generally most negative in which of the following parts of a plant?
A) mesophyll cells of the leaf
B) xylem vessels in leaves
C) xylem vessels in roots
D) cells of the root cortex
E) root hairs
37) Which of the following has the lowest (most negative) water potential?
A) root cortical cells
B) root xylem
C) trunk xylem
D) leaf cell walls
E) leaf air spaces
38) Which of the following is responsible for the cohesion of water molecules?
A) hydrogen bonds between the oxygen atoms of a water molecule and cellulose in a vessel cell
B) covalent bonds between the hydrogen atoms of two adjacent water molecules
C) hydrogen bonds between the oxygen atom of one water molecule and a hydrogen atom of another
water molecule
D) covalent bonds between the oxygen atom of one water molecule and a hydrogen atom of another
water molecule
E) low concentrations of charged solutes in the fluid
39) Transpiration in plants requires all of the following except
A) adhesion of water molecules to cellulose.
B) cohesion between water molecules.
C) evaporation of water molecules.
D) active transport through xylem cells.
E) transport through tracheids.
40) Which of the following statements about transport in plants is false?
A) Weak bonding between water molecules and the walls of xylem vessels or tracheids helps support the
columns of water in the xylem.
B) Hydrogen bonding between water molecules, which results in the high cohesion of the water, is
essential for the rise of water in tall trees.
C) Although some angiosperm plants develop considerable root pressure, this is not sufficient to raise
water to the tops of tall trees.
D) Most plant physiologists now agree that the pull from the top of the plant resulting from transpiration
is sufficient, when combined with the cohesion of water, to explain the rise of water in the xylem in
even the tallest trees.
E) Gymnosperms can sometimes develop especially high root pressure, which may account for the rise
of water in tall pine trees without transpiration pull.
41) Active transport would be least important in the normal functioning of which of the following plant
tissue types?
A) leaf transfer cells
B) stem tracheary elements
C) root endodermal cells
D) leaf mesophyll cells
E) root sieve-tube elements
42) Which of the following statements is false concerning the xylem?
A) Xylem tracheids and vessels fulfill their vital function only after their death.
B) The cell walls of the tracheids are greatly strengthened with cellulose fibrils forming thickened rings
or spirals.
C) Water molecules are transpired from the cells of the leaves, and replaced by water molecules in the
xylem pulled up from the roots due to the cohesion of water molecules.
D) Movement of materials is by mass flow; solutes in xylary sap move due to a positive turgor pressure
gradient from source to sink.
E) In the morning, sap in the xylem begins to move first in the twigs of the upper portion of the tree, and
later in the lower trunk.
43) Xylem vessels, found in angiosperms, have a much greater internal diameter than tracheids, the only
xylem-conducting cells found in gymnosperms. The tallest living trees, redwoods, are gymnosperms.
Which of the following is an advantage of tracheids over vessels for long-distance transport to great
heights?
A) Adhesive forces are proportionally greater in narrower cylinders than in wider cylinders.
B) The smaller the diameter of the xylem, the more likely cavitation will occur.
C) Cohesive forces are greater in narrow tubes than in wide tubes of the same height.
D) Adhesive forces are proportionally greater in narrower cylinders than in wider cylinders, and
cohesive forces are greater in narrow tubes than in wide tubes of the same height.
E) Adhesive forces are proportionally greater in narrower cylinders than in wider cylinders, and the
smaller the diameter of the xylem, the more likely cavitation will occur.
44) Water rises in plants primarily by cohesion-tension. Which of the following is not true about the
cohesion-tension model?
A) Water loss (transpiration) is the driving force for water movement.
B) The “tension” of this model represents the excitability of the xylem cells.
C) Cohesion represents the tendency for water molecules to stick together by hydrogen bonds.
D) The physical forces in the capillary-sized xylem cells make it easier to overcome gravity.
E) The water potential of the air is more negative than the xylem.