36 Chapter Flashcards

1
Q

Phyllotaxy

A

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

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2
Q

Alternate phyllotaxy/ spiral phyllotaxy

A

One leaf per node

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3
Q

Opposite phyllotaxy

A

Two leaves per node

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4
Q

Whorled phyllotaxy

A

More than two leaves per node

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5
Q

Self-pruning

A

Programmed cell death and eventual shedding

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6
Q

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.

A

True

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7
Q

Leaf area index

A

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

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8
Q

Mycorrhizae

A

Mutualistic associations between roots and fungi.

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9
Q

Two major pathways of transport:

A

Apoplast
Symplast

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10
Q

Apoplast

A

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.

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11
Q

Symplast

A

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.

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12
Q

Three routes for transport within a plant tissue or organ:

A

The apoplastic route
Symplastic route
Transmembrane routes

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13
Q

Apoplastic route

A

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

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14
Q

Symplastic route

A

Water and solutes move along the continuum of cytosol.

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15
Q

Transmembrane route

A

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.

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16
Q

Water potential

A

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

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17
Q

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

A

Move into the cell or seed

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18
Q

ψ

A

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

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19
Q

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

A

Megapascal

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20
Q

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

A

True

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21
Q

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

A

True

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22
Q

Water potential equation

A

ψ = ψsubS + ψsubP

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23
Q

Solute potential (osmotic potential)

A

ψsubS

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24
Q

Pressure potential

A

ψsubP

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25
Q

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

A

True

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26
Q

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

A

True

27
Q

Pressure potential is the _____

A

Physical pressure on a solution

28
Q

Turgor pressure

A

When the protoplast presses against the cell wall.

29
Q

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

A

True

30
Q

Flaccid

A

Limp

31
Q

Plasmolysis

A

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

32
Q

Turgid

A

Very firm

33
Q

Wilting

A

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

34
Q

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

A

True

35
Q

Bulk flow

A

The movement of liquid in response to a pressure gradient.

36
Q

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

A

True

37
Q

Unlike osmosis, Bulk flow is independent of solute concentration.

A

True

38
Q

The endodermis functions as…

A

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

39
Q

Casparian strip

A

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

40
Q

Transpiration

A

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

41
Q

Root pressure

A

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

42
Q

Guttation

A

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

43
Q

Dew

A

Condensed atmospheric moisture

44
Q

Cohesion-tension hypothesis

A

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.

45
Q

Negative pressure potential (tension) lowers water potential.

A

True

46
Q

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.

A

True

47
Q

Cavitation

A

The formation of a water vapor pocket

48
Q

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

A

True

49
Q

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

A

True

50
Q

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

A

True

51
Q

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

A

True

52
Q

Three cues that contribute to stomatal opening at dawn:

A

Light
CO2 depletion
Internal “clock” in guard cells

53
Q

Circadian rhythms

A

Cycles with intervals of approximately 24 hours

54
Q

Abscisic acid

A

A hormone that signals guard cells to close stomata.

55
Q

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

A

True

56
Q

Xerophytes

A

Plants adapted to arid environments.

57
Q

Translocation

A

The transport of the products of photosynthesis.

58
Q

Phloem sap

A

The aqueous solution that flows through sieve tubes

59
Q

Sugar source

A

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

60
Q

Sugar sink

A

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

61
Q

Pressure flow

A

Positive pressure used in bulk flow

62
Q

Self-thinning

A

Process where plant aborts some flowers, seeds, or fruits

63
Q

Symplastic domains

A

Interconnected regions within a plant where cytoplasm can freely flow.