The movement of water out of phloem sap and back into xylem vessels is often associated with which of the following events?active transport of water out of the phloem sap into a sourceа.b. passive diffusion of phloem sap into a sourceactive transport of sugars out of the phloem sap into a sinkC.hydrostatic push (pressure) forcing phloem sap into a sinkOd.

C. Active transport of sugar out of phloem sap into the sink.

he movement of water out of phloem sap and back into xylem vessels is often associated with which of thne following events? a, active transport of water out of the phloem sap into a source b. passive diffusion of phloem sap into a source active transport of sugars out of the phloem sap into a sink hydrostatic push (pressure) forcing phloem sap into a sink

he movement of water out of phloem sap and back into xylem vessels is often associated with which of thne following events? a, active transport of water out of the phloem sap into a source b. passive diffusion of phloem sap into a source active transport of sugars out of the phloem sap into a sink hydrostatic push (pressure) forcing phloem sap into a sink

BIOLOGY:CONCEPTS+APPL.(LOOSELEAF)

10th Edition

ISBN:9781305967359

Author:STARR

Publisher:STARR

Chapter26: Plant Nutrition And Transport

Section: Chapter Questions

Problem 14SA

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There is a trade-off between photosynthesis and transpiration in leaves because (a) numerous stomatal pores provide both gas exchange for photosynthesis and openings through which water vapor escapes (b) a waxy layer, the cuticle, reduces water loss (c) blue light triggers an influx of potassium ions (K+) into the guard cells (d) leaves of deciduous plants abscise as winter approaches in temperate climates (e) stomata are closed at night, although water continues to move into the roots by osmosis
According to the pressure-flow model, sugar is actively transported into phloem anda. enters xylem, where it is moved toward the leaves due to transpiration.b. creates pressure to move water toward the roots.c. is transported out of the leaves through stomata.d. water follows by osmosis, providing pressure that moves the water and sugar through the phloem.
Which of the following statements is/are false? A. Water is actively transported from source cells into companion cells. B. The transport of sucrose into the Osieve tube elements increases water potential in the phloem. C. The transport of water from the xylem into the phloem increases the O pressure which forces the sucrose water mixture down towards the sink. D. Transpiration cause the water to O move up to the leaves through the vessel elements. E. A and B F. B and C
The pressure-flow model of phloem transport states thata. phloem content always flows from the leaves to the root.b. phloem content always flows from the root to the leaves.c. water flow takes sucrose from a source to a sink.d. water pressure creates a flow of water toward the source.e. Both c and d are correct.
When considering the loading and unloading of photosynthate from the phloem, which of the following is FALSE? Select one: a. Apoplastic phloem unloading enables the import of sugars against their concentration gradient into sink tissue. b. In apoplastic loading, the solute potential of the companion cells is more negative than the apoplastic space nearby. c. In apoplastic loading, proton pumps create electrochemical gradients that can be used by symporter proteins to import sugars into the companion cell. d. All the statements are true. e. Symplastic loading relies on diffusion of the sugars through plasmodesmata from photosynthetic cells to the phloem cells.
Water movement through the xylem needs less pressure than movement through living cells. A. Agree, because water moves in xylem through diffusion. B. Disagree, because water needs turgor pressure in order to diffuse. D. Disagree, beacuse both need equal pressure for materials to pass through xylem and living cells like sievetubes. C. Agree, because water is non-living while photosynthates are living and must pass through living cells that require pressure.
Which of the following statements is inaccurate?a. Water that evaporates from leaves is ultimately replaced by water diffusing from the xylem.b. Xylem transports water up the plant while phloem transports carbohydrates throughout the plant.c. Water movement in the xylem is largely due to the pressure-flow hypothesis.d. Water movement across membranes is often due to differences in solute concentrations.
The process of bulk flow transports fluids in a plant. What are the two main bulk flow processes? * A. Movement of water up the xylem and movement of solutes up and down the phloem B. Movement of water up the phloem and movement of solutes up and down the xylem C. Movement of water up and down the xylem and movement of solutes up the phloem D. Movement of solutes up the xylem and movement of water up and down the phloem E. Movement of solutes down the phloem and movement of water up and down the xylem F. Movement of solutes down the phloem and movement of water up the xylem
Which of the following is/are false regarding the phloem? A. It transports starch from the leaves to the stem. B. It transports sucrose from the leaves to the roots. C. It is located lateral to the xylem in tree stems. D. Unlike the xylem, majority of the cells are living. E. A and D F. B and C
Movement of phloem sap from a source to a sink(A) occurs through the apoplast of sieve-tube elements.(B) depends ultimately on the activity of proton pumps.(C) depends on tension, or negative pressure potential.(D) results mainly from diffusion.