36 Chapter

Question 1

Phyllotaxy

Answer 1

The arrangement of leaves on a stem.
-Determined by the shoot apical meristem

Question 2

Alternate phyllotaxy/ spiral phyllotaxy

Answer 2

One leaf per node

Question 3

Opposite phyllotaxy

Answer 3

Two leaves per node

Question 4

Whorled phyllotaxy

Answer 4

More than two leaves per node

Question 5

Self-pruning

Answer 5

Programmed cell death and eventual shedding

Question 6

In low light conditions, horizontal leaves capture sunlight much more effectively than vertical leaves. In sunny regions, horizontal leaves may be damaged from overly intense light, while vertical leaves are not and light penetrates more deeply to lower leaves.

Answer 6

True

Question 7

Leaf area index

Answer 7

The ratio of the total area of the tip surfaces of the leaves to the area of ground covered by the plant.

Question 8

Mycorrhizae

Answer 8

Mutualistic associations between roots and fungi.

Question 9

Two major pathways of transport:

Answer 9

Apoplast
Symplast

Question 10

Apoplast

Answer 10

Consists of everything external to the plasma membrane of living cells and includes cell walls, extracellular spaces, and the interior of dead cells such as vessel elements and tracheids.

Question 11

Symplast

Answer 11

Consists of the entire mass of cytosol of all the living cells in a plant, as well as the plasmodesmata, the cytoplasmic channels that interconnect them.

Question 12

Three routes for transport within a plant tissue or organ:

Answer 12

The apoplastic route
Symplastic route
Transmembrane routes

Question 13

Apoplastic route

Answer 13

Water and solutes move along the continuum of cell walls and extracellular spaces.

Question 14

Symplastic route

Answer 14

Water and solutes move along the continuum of cytosol.

Question 15

Transmembrane route

Answer 15

Water and solutes move out of one cell, across the cell wall, and into the neighboring cell, which may pass them to the next cell in the same way.

Question 16

Water potential

Answer 16

The physical property that predicts the direction in which water will flow.
-A quantity that includes the effects of solute concentration and physical pressure.

Question 17

If a plant or seed is immersed in a solution that has a higher water potential, water will…

Answer 17

Move into the cell or seed

Question 18

ψ

Answer 18

Water potential.
Greek letter pronounced “sigh” (psi)

Question 19

Plant biologists measure water potential in a unit of pressure called a __________

Answer 19

Megapascal

Question 20

The ψ of pure water in a container open to the atmosphere under standard conditions is 0 MPa.

Answer 20

True

Question 21

One MPa is equal to about 10 times atmospheric pressure at sea level.

Answer 21

True

Question 22

Water potential equation

Answer 22

ψ = ψsubS + ψsubP

Question 23

Solute potential (osmotic potential)

Answer 23

ψsubS

Question 24

Pressure potential

Answer 24

ψsubP

Question 25

The solute potential of a solution is directly proportional to its molarity.

Answer 25

True

Question 26

The solute concentration of a solution is always expressed as a negative number.

Answer 26

True

Question 27

Pressure potential is the _____

Answer 27

Physical pressure on a solution

Question 28

Turgor pressure

Answer 28

When the protoplast presses against the cell wall.

Question 29

Water moves from regions of higher water potential to regions of lower water potential.

Answer 29

True

Question 30

Flaccid

Answer 30

Limp

Question 31

Plasmolysis

Answer 31

When the protoplast shrinks and pulls away from the cell wall.

Question 32

Turgid

Answer 32

Very firm

Question 33

Wilting

Answer 33

When leaves or stems droop as a result of cells loosing water.

Question 34

Aquaporin channels affect the rate at which water moves osmotically across the membrane.

Answer 34

True

Question 35

Bulk flow

Answer 35

The movement of liquid in response to a pressure gradient.

Question 36

The bulk flow of material always occurs from higher to lower pressure.

Answer 36

True

Question 37

Unlike osmosis, Bulk flow is independent of solute concentration.

Answer 37

True

Question 38

The endodermis functions as…

Answer 38

A last checkpoint for the selective passage of minerals from the cortex into the vascular cylinder.

Question 39

Casparian strip

Answer 39

A water impermeable ring of suberin in the endodermis cells of plants that blocks the passive flow of water and solutes into the stele by way of cell walls. -Present in the apoplastic route

Question 40

Transpiration

Answer 40

The loss of water vapor from leaves and other aerial parts of the plant.

Question 41

Root pressure

Answer 41

A push of xylem sap generated by water flowing in from the root cortex

Question 42

Guttation

Answer 42

The exudation of water droplets that can be seen in the morning on the tips or edges of some plant leaves.

Question 43

Dew

Answer 43

Condensed atmospheric moisture

Question 44

Cohesion-tension hypothesis

Answer 44

Proposes that transpiration provides the pull for the ascent of xylem sap, and the cohesion of water molecules transmits this pull along the entire length of the xylem from shoots to roots.

Question 45

Negative pressure potential (tension) lowers water potential.

Answer 45

True

Question 46

The tension produced by transpirational pull lowers water potential in the root xylem to such an extent that water flows passively from the soil, across the root cortex, and into the vascular cylinder.

Answer 46

True

Question 47

Cavitation

Answer 47

The formation of a water vapor pocket

Question 48

Evaporation lowers the water potential at the air-water interface, thereby generating the negative pressure (tension) that pulls water through the xylem.

Answer 48

True

Question 49

When guard cells lose water and become flaccid, the pore closes.

Answer 49

True

Question 50

The changes in turgor pressure in guard cells result primarily from the reversible absorption and loss of K+.

Answer 50

True

Question 51

Stomata open when guard cells actively accumulate K+ from neighboring epidermal cells.

Answer 51

True

Question 52

Three cues that contribute to stomatal opening at dawn:

Answer 52

Light CO2 depletion Internal “clock” in guard cells

Question 53

Circadian rhythms

Answer 53

Cycles with intervals of approximately 24 hours

Question 54

Abscisic acid

Answer 54

A hormone that signals guard cells to close stomata.

Question 55

Freely available water allow plants to keep stomata open and take up more CO2.

Answer 55

True

Question 56

Xerophytes

Answer 56

Plants adapted to arid environments.

Question 57

Translocation

Answer 57

The transport of the products of photosynthesis.

Question 58

Phloem sap

Answer 58

The aqueous solution that flows through sieve tubes

Question 59

Sugar source

Answer 59

A plant organ that is a net producer of sugar, by photosynthesis or by breakdown of starch.

Question 60

Sugar sink

Answer 60

An organ that is a net consumer or depository of sugar.

Question 61

Pressure flow

Answer 61

Positive pressure used in bulk flow

Question 62

Self-thinning

Answer 62

Process where plant aborts some flowers, seeds, or fruits

Question 63

Symplastic domains

Answer 63

Interconnected regions within a plant where cytoplasm can freely flow.