Chapter 36 - Transport in Plants

1 The Casparian strip in a plant root blocks transport of water and minerals traveling in the:

        A. symplast
        B. apoplast
        C. cytoplasm
        D. plasmodesmata
        E. xylem

.2 When a soil mineral is absorbed by a root, which sequence of tissues below is the correct pathway?

        A. Epidermis -> stele (vascular cylinder) -> cortex endodermis
        B. Epidermis -> endodermis -> cortex -> stele
        C. Epidermis -> cortex -> endodermis -> stele
        D. Epidermis -> cortex stele -> endodermis
        E. Endodermis -> stele -> cortex -> xylem

B 32.3 The Casparian strip in a plant root is part of the:
        A. epidermis
        B. endodermis
        C. cortex
        D. xylem
        E. symplast

4 A plant cell will- plasmolyze in an environment that is:

        A. hypotonic to the cell only
        B. isotonic to the cell only
        C. hypertonic to the cell only
        D. of a higher (less negative) water potential than the
            cell only
        E. both hypertonic and of a higher water potential than
            the cell

5 According to the transpiration-cohesion theory, upward movement of water in xylem is powered mainly by:

        A. root pressure
        B. the active transport of sucrose
        C. solar energy
        D. ATP
        E. pressure flow

6 The movement of water up stems is mainly the. result of:

        A. root pressure
        B. transpiration
        C. the active transport of water into xylem vessels
        D. the active transport of water from xylem vessels
            into the cells of the leaf
        E. leaf cells' having a higher water potential than
            root cells do

7 Guttation in plants is a consequence of:

A. root pressure
B. transpiration
C. pressure-flow in phloem
D. plant injury
E. condensation of atmospheric water

8 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. stomata are wide open
E. roots are not absorbing minerals from the soil

9 Water potential is generally most negative in which of the following parts of a plant?

        A. Mesophyll cells
        B. Xylem vessels in leaves
        C. Xylem vessels in roots
        D. Cells of the root cortex
        E. Root hairs

10 Photosynthesis begins to decline when leaves wilt because:

        A. flaccid cells are incapable of photosynthesis
        B. C02 accumulates in the leaves and inhibits
        C. there is insufficient water for photolysis during
            light reactions
        D. stomata close, preventing C02 entry into the leaf
        E. the chlorophyll of flaccid cells cannot absorb light

11 Ignoring all other factors, what kind of day would result in the fastest delivery of water and minerals to the leaves of a tree?

        A. Cool, dry day
        B. Warm, dry day
        C. Warm, humid day
        D. Cool, humid day
        E. Very hot, dry, windy day

12 Stomata open when the guard cells:

        A. lose turgor pressure
        B. accumulate potassium only
        C. lose water
        D. increase their turgor pressure only
        E. accumulate potassium and increase their turgor pressure

13 Which of the following is a correct statement about sugar movement in phloem?

        A. Diffusion can account for the observed rates of transport
        B. Movement can occur both upwards and downwards in the plant
        C. Sugar is translocated from sinks to sources
        D. Only phloem cells with nuclei can perform sugar movement
        E. Sugar transport does not require ATP

14 A twig falls from the top of a very tall tree. Examination of the broken surface with a dissecting microscope reveals the vascular tissue, some cells of which are exuding sugarcontaining fluid through their broken ends. This fluid is probably:

        A. xylem sap only
        B. water only
        C. phloem sap only
        D. guttation fluid only
        E. both xylem sap and water

15 In the pressure-flow hypothesis of translocation, the pressure results from:

        A. root pressure
        B. the osmotic uptake of water by sieve tubes at the source
        C. the accumulation of minerals and water by the stele in the root
        D. the osmotic uptake of water by the sieve tubes of the sink
        E. hydrostatic pressure in xylem vessels

B16 Which one of the following is NOT a factor in the movement of water through a terrestrial plant?

        A. Hydrogen bonds linking water molecules
        B. The influence of gibberellin on cell expansion
        C. Capillary action due to the adhesion of water molecules to the walls of thin tubes
        D. Root pressure
        E. Evaporation of water from the leaves

        1. Water diffuses into the sieve elements
        2. Leaf cells produce sugar by photosynthesis
        3. Solutes are actively transported into sieve elements
        4. Sugar is transported from cell to cell in the leaf
        5. Sugar moves down the stem

17 Which of the following represents a correct ordering of the events above, which explains the mass flow of materials in the phloem?

        A. 1 - 2 - 3 - 4 - 5
        B. 2 - 1 - 4 - 3 - 5
        C. 2 - 4 - 1 - 3 - 5
        D. 2 - 4 - 3 - 1 - 5
        E. 4 - 2 - 1 - 3 - 5

18 At the moment, the most accepted mechanism of guard cell opening is:

        A. the pH hypothesis
        B. the sugar-osmosis hypothesis
        C. the K+ transport hypothesis
        D. the cytoskeleton hypothesis
        E. none of the above

19 During intense transpiration, the ultimate source of energy powering the  rise of water through the plant is:

        A. ATP
        B. sugars
        C. osmotic pressure in the root
        D. sunlight
        E. root pressure

20 All of the following statements about transport in plants are correct EXCEPT:

        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 transport is sufficient, when combined with the cohesion of water, to
             explain the rise of water in the xylem, even in 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

21 Water flows into the source end of a sieve tube because:

        A. sucrose has diffused into the sieve tube, making it hypertonic
        B. sucrose has been actively transported into the sieve tube, making it hypertonic
        C. water pressure outside the sieve tube forces water in
        D. the companion cell of a sieve tube actively pumps water in
        E. sucrose has been dumped from the sieve tube by active transport

22 At the sink end of a phloem tube, sucrose doesn't diffuse back into the sieve tube because:

        A. the sucrose concentration is lower in the cells surrounding the sieve tube
        B. transport proteins will not move the sucrose in that direction
        C. the structure of the cell wall of a sieve tube opposes movement in that direction
        D. the flow of water out of the sieve tube washes back any sucrose that attempts to do so
        E. there isn't enough solvent in the sieve tube

23 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; materials move owing to a 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

24 Which of the following has the lowest (most negative) water potential?

        A. Soil
        B. Root xylem
        C. Trunk xylem
        D. Leaf cell walls
        E. Leaf air spaces

25 Which of the following factors that sometimes plays a role in the rise of sap in the xylem, depends on the expenditure of ATP energy by the plant?

        A. Secretion of ions into the stele of the root
        B. Cohesion of water molecules due to hydrogen bonding
        C. Transpiration of water from the leaves
        D. Capillarity of water in xylem tracheids and vessels
        E. Diffusion of water into the root hairs

26 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 xylem cells

27 Which of the following statements about xylem is incorrect?

        A. Xylem conducts material upward
        B. Xylem conduction occurs within dead cells
        C. Xylem carries sugars and amino acids
        D. Xylem has a lower water potential than the soil does
        E. No energy input from the plant is required for xylem

28 Root hairs are most important to a plant because they:

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

29 All of the following are important factors controlling stomate size EXCEPT:

        A. K+ concentration in guard cells
        B. carbon dioxide concentration in guard cells
        C. water potential of the guard cells
        D. ATP concentration in the chloroplasts
        E. photosynthesis in the guard cells

30 Which of the following is a sink for organic compounds?

        A. Xylem
        B. Phloem
        C. Roots
        D Chloroplasts
        E. Tonoplast

31 Which of the following is not an adaptation that helps reduce water loss from a plant?

        A. Transpiration
        B. Sunken stomates
        C. C4 photosynthesis
        D. Small, thick leaves
        E. Crassulacean acid metabolism

32 Water entering the stele laterally must first pass through the:

        A. Casparian strip
        B. endodermal walls
        C. endodermal cytoplasm
        D. epidermis
        E.  apoplast



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