Movement of the phloem sap is bidirectional (may be up and down) depending to the location of sink cells. Sucrose enters the phloem from the source cells through the companion cells. Internal pressure differences drive the phloem sap along the sieve tube to sink cells. Water transfers to the xylem by osmosis raising the pressure potential on the sieve tube. Sucrose is unloaded into sink cells increasing the water potential in the sieve tube.

Movement of the phloem sap is bidirectional (may be up and down) depending to the location of sink cells. Sucrose enters the phloem from the source cells through the companion cells. Internal pressure differences drive the phloem sap along the sieve tube to sink cells. Water transfers to the xylem by osmosis raising the pressure potential on the sieve tube. Sucrose is unloaded into sink cells increasing the water potential in the sieve tube.

Biology (MindTap Course List)

11th Edition

ISBN:9781337392938

Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Publisher:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Chapter35: Stem Structure And Transport

Section: Chapter Questions

Problem 7TYU: Water potential is (a) the formation of a proton gradient across a cell membrane (b) the transport...

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Water potential is (a) the formation of a proton gradient across a cell membrane (b) the transport of a watery solution of sugar in phloem (c) the transport of water in both xylem and phloem (d) the removal of sucrose at the sink, causing water to move out of the sieve tubes (e) the free energy of water in a particular situation
Figure 30.34 Which of the following statements is false? Negative water potential draws water into the root hairs. Cohesion and adhesion draw water up the xylem. Transpiration draws water from the leaf. Negative water potential draws water into the root hairs. Cohesion and adhesion draw water up the phloem. Transpiration draws water from the leaf. Water potential decreases from the roots to the top of the plant. Water enters the plants through root hairs and exits through stoma.
Ground tissue in monocot stems performs the same functions as _______________ and _______________ in herbaceous eudicot stems. (a) phloem; xylem (b) cork cambium; vascular cambium (c) epidermis; periderm (d) primary xylem; secondary xylem (e) cortex; pith
Which plant water movement process is dependent on transpiration? root pressure capillary action cohesion-tension all of the above
The following statements are correct except* a. Assimilates are transported from areas of supply to areas of metabolism or storage. b. The transport of assimilates in the phloem is bi-directional. c. Allocation is the distribution of assimilates to competing sinks. d. Sugars, phytohormones and amino acids are transported in the phloem.
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.
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
Which of the following statements are true for root endodermis?I. Endodermal cells constitute the innermost layer of root cortex and surrond the vascular cylinder (xylem and phloem). II. Endodermal wall is covered with waxy layer of casparian strip which blocks apoplastic transfer of minerals.III. Due to presence of casparian strip, water and minerals can only eneter the vascular cylinder if they will be able to cross the plasma membrane of an endodermal cell.
Which of the following is a mechanism of water movement in xylem that combines the evaporative pull of transpiration with the cohesive and adhesive properties of water? (a) pressure– flow (b) tension–cohesion (c) root pressure (d) active transport of potassium ions into guard cells (e) guttation
Which of the following forces make the movement of water through the xylem possible? * A. Cohesion and adhesion B. Transpiration C. Root pressure D. A and B E. A, B, and C
You could prevent most of a plant's secondary growth by: Destroying the phloem portion of the vascular cambium It would require the combination of at least two of these Removing the apical or basal meristems Destroving the cork cambium Destroying the xylem portion of the vascular cambium