Chapter 36 Mastering Biology

c. Maximizing photosynthesis ... minimizing water loss

1. Plants must always compromise between _____ and _____. a. Maximizing transport minerals ... minimizing transport of sugars b. Maximizing water loss ... minimizing H+ protons c. Maximizing photosynthesis ... minimizing water loss d. Maximizing access to light ... minimizing intake of CO2 e. Maximizing water absorption ... minimizing leaf area

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10. The path of water movement in leaves: Water follows a specific path as it moves from the xylem in the vein of a leaf to the air outside the leaf. Drag the labels into the flowchart to show the sequence of events after water enters a leaf in the xylem. Not all labels will be used.

c. To minimize water loss during dry conditions, most plants must also restrict their ability to carry out photosynthesis. d. Open stomata provide a low-resistance pathway for CO2 to enter and for water to exit the leaf. e. In most plants, the highest rate of transpiration occurs when the rate of photosynthesis is also highest. f. Transpiration is important in cooling leaves on warm, sunny days.

11. The relationship between transpiration and other processes in plants: Transpiration provides the driving force for the movement of water from the soil to the highest leaves of plants. Transpiration is also linked to other processes in plants, including photosynthesis and the transport of mineral nutrients. Which of the following statements correctly describe(s) a relationship between transpiration and other processes in plants? Select all that apply. a. Water is pulled from the roots to the leaves by transpiration, whereas mineral nutrients diffuse from the roots to the leaves. b. The large surface area exposed to air inside the leaf maximizes the plant's ability to absorb CO2 while minimizing water loss through transpiration. c. To minimize water loss during dry conditions, most plants must also restrict their ability to carry out photosynthesis. d. Open stomata provide a low-resistance pathway for CO2 to enter and for water to exit the leaf. e. In most plants, the highest rate of transpiration occurs when the rate of photosynthesis is also highest. f. Transpiration is important in cooling leaves on warm, sunny days.

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12. Label each target to indicate if the interaction between the molecules inside the rectangle contributes to surface tension (T), adhesion (A), or cohesion (C). Note that one target should be left blank because the molecules inside that rectangle are not involved in any of these interactions.

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13. Processes that affect the strength of transpirational pull: Water's properties of surface tension, cohesion, and adhesion are central to the ability of transpiration to pull water up from the roots to the leaves through the xylem. Sort each statement into the appropriate bin to indicate if the change described in the statement would increase, decrease, or not affect the pull that transpiration generates in the xylem of a tree.

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14. Drag a label to each target in the table to indicate the role that surface tension, adhesion, and cohesion play in the transport of water in the xylem. Labels may be used more than once. (Hint: The label "generates pull" belongs in only one target in the table.)

a. Receptor proteins in the membrane

2. Which of the following would be LEAST likely to affect osmosis in plants? a. Receptor proteins in the membrane b. A difference in solute concentrations c. A difference in water potential d. Aquaporins

e. Lose water and plasmolyze

3. A plant cell placed in a solution with a lower (more negative) water potential will _____. a. Gain water and become turgid b. Lose water and burst c. Gain water and plasmolyze d. Lose water and become turgid e. Lose water and plasmolyze

e. Sugar

4. The solute most abundant in phloem sap is _____. a. Minerals b. Hormones c. Water d. Amino acids e. Sugar

e. Xylem sap moves up; phloem sap moves up or down.

5. Which of the following is a correct statement about a difference between xylem and phloem transport? a. Active transport moves xylem sap but not phloem sap. b. Xylem sap moves from sugar source to sink, but phloem sap does not. c. Transpiration moves phloem sap but not xylem sap. d. Phloem carries water and minerals; xylem carries organic molecules. e. Xylem sap moves up; phloem sap moves up or down.

d. An increase in the solute concentration of the guard cells

6. The opening of the stomata is thought to involve _____. a. Active transport of water out of the guard cells b. Decreased turgor pressure in guard cells c. Movement of K+ from the guard cells d. An increase in the solute concentration of the guard cells

c. Ensures that all water and dissolved substances must pass through a cell membrane before entering the stele

7. In plant roots, the Casparian strip _____. a. Ensures that all minerals are absorbed from the soil in equal amounts b. Aids in the uptake of nutrients c. Ensures that all water and dissolved substances must pass through a cell membrane before entering the stele d. Provides energy for the active transport of minerals into the stele from the cortex

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8. Key structures involved in water transport in a leaf: A plant leaf is constructed from a variety of cell types with specialized structures and functions. Many of the properties of leaf cells facilitate some aspect of water transport. The diagram below shows a cross section through a leaf. Drag the labels to the appropriate targets to match the function with the structure indicated in the diagram. Labels may be used once, more than once, or not at all.

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9. The apoplastic and symplastic pathways for water transport: The apoplast and symplast are two regions of the plant that serve as pathways for water and solute transport over both short and long distances. These pathways are represented by the arrows in the diagram below, which shows three adjacent cells in a leaf or root. Sort each statement into the appropriate bin. Substitute the term "cytoplasm" for "protoplast" in one of the boxes below.