Chapter 36 - Resource Acquisition and Transport in Vascular Plants

Question 1

phyllotaxy

Answer 1

The pattern of leaf attachment to the stem of a plant.

Question 2

mycorrhiza

Answer 2

A mutualistic association of plant roots and fungus.

Question 3

apoplast

Answer 3

Everything external to the plasma membrane of a plant cell, including cell walls, intercellular spaces, and the space within dead structures such as xylem vessels and tracheids.

Question 4

symplast

Answer 4

In plants, the continuum of cytoplasm connected by plasmodesmata between cells.

Question 5

osmosis

Answer 5

The diffusion of free water across a selectively permeable membrane.

Question 6

water potential (Ψ)

Answer 6

The physical property predicting the direction in which water will flow, governed by solute concentration and applied pressure.

Question 7

megapascal (MPa)

Answer 7

A unit of pressure equivalent to about 10 atmospheres of pressure.

Question 8

solute potential

Answer 8

A component of water potential that is proportional to the molarity of a solution and that measures the effect of solutes on the direction of water movement; also called osmotic potential, it can be either zero or negative.

Question 9

pressure potential

Answer 9

A component of water potential that consists of the physical pressure on a solution, which can be positive, zero, or negative.

Question 10

protoplast

Answer 10

The living part of a plant cell, which also includes the plasma membrane.

Question 11

turgor pressure

Answer 11

The force directed against a plant cell wall after the influx of water and swelling of the cell due to osmosis.

Question 12

flaccid

Answer 12

Lacking turgor (stiffness or firmness), as in a plant cell in surroundings where there is a tendency for water to leave the cell. (A walled cell becomes flaccid if it has a higher water potential than its surroundings, resulting in the loss of water.)

Question 13

plasmolysis

Answer 13

A phenomenon in walled cells in which the cytoplasm shrivels and the plasma membrane pulls away from the cell wall; occurs when the cell loses water to a hypertonic environment.

Question 14

turgid

Answer 14

Swollen or distended, as in plant cells. (A walled cell becomes turgid if it has a lower water potential than its surroundings, resulting in entry of water.)

Question 15

wilting

Answer 15

The drooping of leaves and stems as a result of plant cells becoming flaccid.

Question 16

aquaporin

Answer 16

A channel protein in the plasma membrane of a plant, animal, or microorganism cell that specifically facilitates osmosis, the diffusion of free water across the membrane.

Question 17

bulk flow

Answer 17

The movement of fluid due to a difference in pressure between two locations.

Question 18

endodermis

Answer 18

In plant roots, the innermost layer of the cortex that surrounds the vascular cylinder.

Question 19

Casparian strip

Answer 19

A water-impermeable ring of wax in the endodermal cells of plants that blocks the passive flow of water and solutes into the stele by way of cell walls.

Question 20

xylem sap

Answer 20

The dilute solution of water and dissolved minerals carried through vessels and tracheids.

Question 21

transpiration

Answer 21

The evaporative loss of water from a plant.

Question 22

root pressure

Answer 22

Pressure exerted in the roots of plants as the result of osmosis, causing exudation from cut stems and guttate of water from the leaves.

Question 23

guttation

Answer 23

The exudation of water droplets from leaves, caused by root pressure in certain plants.

Question 24

cohesion-tension hypothesis

Answer 24

The leading explanation of the ascent of xylem sap. It states that transpiration exerts pull on xylem sap, putting the sap under negative pressure or tension, and that the cohesion of water molecules transmits this pull along the entire length of the xylem from shoots to roots.