BIO- Chapter 36 – Flashcards
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Plants must always compromise between _____ and _____.
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maximizing photosynthesis ... minimizing water loss
(Structures, such as broad leaves, that enhance photosynthesis also maximize water loss. Plant form is generally a compromise between the two, depending on the plant's environment.)
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A plant cell placed in a solution with a lower (more negative) water potential will _____.
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lose water and plasmolyze
(Water moves from a region of higher water potential to a region of lower water potential. Loss of water pulls the plasma membrane away from the cell wall, producing plasmolysis.)
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A student is performing a chemical analysis of xylem sap. This student should not expect to find much _____.
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sugar
(Phloem, not xylem, transports sugar.)
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Mycorrhizae are _____.
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mutualistic associations between plant roots and fungi
(Mycorrhizae greatly improve absorption of minerals and water from the soil.)
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The proton pump _____.
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uses the energy stored in ATP to produce a hydrogen ion gradient across membranes.
(This proton gradient occurs across a membrane)
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Which tissue acts as a filter on the water absorbed by root hairs?
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Endodermis
(Endodermal cells filter solutes from water and allow them to pass through to the vascular tissue.)
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True or false? Root pressure can move water a long distance up the xylem because of the higher water potential of the xylem in comparison to the water potential in the surrounding cells.
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False
(Root pressure can move water a short distance up the xylem because of the lower water potential of the xylem in comparison to the water potential in the surrounding cells.)
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Which of the following statements about the distribution of sap throughout a plant is true?
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The mechanism that explains the movement of sugars throughout a plant is called the pressure-flow hypothesis.
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Which term describes an area where sugars are used or stored?
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Sink
(A sink is an area where sugars are used or stored; typically, these are the roots and fruits of a plant.)
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Which of the following statements about xylem transport is true?
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Water and minerals move through the root cortex into the xylem and upward through the stem and into leaves.
(Water and minerals that are taken up in the soil are transported from roots to leaves by the xylem.)
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What characterizes the rates of photosynthesis and transport in a plant on a dry cloudy day?
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Both the photosynthesis and transpiration rates are low.
(On a cloudy day with low soil moisture, the photosynthesis rate is low and stomata are closed, so the transpiration rate is low.)
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True or false? The rate of sugar transport in a plant depends on the rate of photosynthesis, the rate of transpiration, and the difference in turgor pressure between the source and the sink.
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False
(While the rate of photosynthesis and the difference in turgor pressure between the source and the sink do influence the rate of sugar transport in the phloem, the rate of transpiration does not; transpiration mainly influences the rate of water transport through the xylem.)
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Which of the following is an adaptation that enhances the uptake of water and minerals by roots?
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mycorrhizae
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Which structure or compartment is part of the symplast?
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the interior of a sieve tube
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Movement of phloem sap from a source to a sink
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depends ultimately on the activity of proton pumps.
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Photosynthesis ceases when leaves wilt, mainly because
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stomata close, preventing CO2 from entering the leaf.
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What would enhance water uptake by a plant cell?
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positive pressure on the surrounding solution
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Compared with a cell with few aquaporin proteins in its membrane, a cell containing many aquaporin proteins will
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have a faster rate of osmosis
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Which of the following would tend to increase transpiration?
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higher stomatal density
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A plant cell with a ψs of -0.65 MPa maintains a constant volume when bathed in a solution that has a ψs of -0.30 MPa and is in an open container. The cell has a
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ψp of +0.35 MPa.
