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BIO107 General Physiology Lecture > Module 2 > Flashcards

Module 2 Flashcards

1
Q

True or False

Water is important to the physiology of plants because of its crucial role in all physiological processes and because of the SMALL quantities that are required.

A

False

LARGE

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2
Q

How much water is found in the biomass in some non woody tissues such as leaves and roots?

A

70-95%

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3
Q

At the cellular level, ___ is the major medium for transporting metabolites through the cell.

A

water

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4
Q

True or False

Water readily dissolves LARGE quantities of ions and polar organic metabolites like sugars, amino acids, and proteins that are critical to metabolism and life.

A

True

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5
Q

___ is the medium that transports the raw materials (carbohydrates and nutrients) as well as the phytohormones that are required for the growth and development from one plant organ to another.

A

water

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6
Q

True or False

Living cells must maintain a NEGATIVE water pressure, or “turgor” to grow and function properly.

A

False

POSITIVE

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7
Q

True or False

Plants lose SMALL quantities of water in transpiration.

A

False

LARGE

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8
Q

___ is the evaporation of water from the interior of leaves through the stomata.

A

transpiration

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9
Q

How much (%) water do plants lose in one hour during transpiration?

A

100%

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10
Q

Why do plants rapidly lose water during transpiration?

A

Plants lose water rapidly during transpiration because of their large surface area and the high rate of evaporation in their leaves.

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11
Q

What is heat dissipation by leaves through transpiration?

A

Heat dissipation by leaves through transpiration is the process of plants losing water vapor into the atmosphere through their leaves, which helps to cool the plant.

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12
Q

How much heat by sunlight is dissipated by transpiration?

A

half

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13
Q

What is latent heat of vaporization?

A

Latent heat of vaporization is the amount of heat energy required to convert a unit mass of a liquid to a vapor at a constant temperature. It is a measure of the energy required to break the intermolecular bonds between liquid molecules and allow them to escape into the gas phase.

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14
Q

___, also referred to as low resistance pores, are biological membranes to which water passes through.

A

aquaporins

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15
Q

___ are proteins embedded in the cell membrane that regulate flow of water.

A

aquaporins

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16
Q

How do aquaporins regulate the flow of water in the cell membrane?

A

Aquaporins regulate the flow of water in the cell membrane by opening and closing their channels.

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17
Q

The opening and closing of stomatal pores are based on ___.

A

short distance intercellular transport

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18
Q

Water potential (🔱), or psi, measures the combined effects of : (2)

A
  1. solute concentration
  2. physical pressure (of the cell wall)
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19
Q

Water potential (🔱) is measured in ____.

A

MPa (megapascals)

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20
Q

1 MPa is equal to ____ of pressure.

A

10 atmospheres

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21
Q

What is the formula of water potential?

A

🔱w = 🔱s + 🔱p + 🔱g

🔱w —> water potential
🔱s —> solute potential
🔱p —> pressure potential
🔱g—> gravitational potential

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22
Q

___ is the effect of dissolved solutes on water potential.

A

solute potential

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23
Q

___ reduce the free energy of water.

A

solutes

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24
Q

___ is the hydrostatic pressure of a solution.

A

pressure potentail

25
Q

Positive pressure ____ the water potential,
while negative pressure ___ it.

A

raises;
decreases

26
Q

Positive pressure refers to ____,
negative pressure refers to ___.

A

turgor;
tension

27
Q

___ is generally negligible; it is overcame by a transpirational pull.

A

gravity potential

28
Q

____, ____, and ____ are all strongly influenced by water potential and its components.

A

cell growth, photosynthesis, and crop productivity

29
Q

True or False

Water potential is a good indicator of plant health.

A

True

30
Q

Water always moves from a ___ water potential to ___ water potential.

A

higher;
lower

31
Q

____ is the passive movement of water from roots into soil layers with lower water potential, while other parts of the root system in moister soil layers, usually at depth, are absorbing water.

A

hydraulic lift

32
Q

____ allows the survival of shallow-rooted plants during drought, or in arid environments.

A

hydraulic lift

33
Q

The hydraulic lift is also referred to as the _____ or _____.

A

cohesion-tension theory;
transpiration pull theory

34
Q

____ are responsible for increasing the surface area of the roots, which enhances their ability to absorb water and nutrients from the soil.

A

root hairs

35
Q

____ are the most active in the water absorption process.

A

root hairs

36
Q

Water enters the root most readily in the ____ part of the root that includes the root hair zone.

A

apical

37
Q

What are the three (3) pathways for water uptake by the root?

A
  1. apoplast pathway
  2. symplast pathway
  3. transmembrane transport
38
Q

What happens in the symplast, transmembrane, and apoplast pathway?

A

In the symplast pathway, water flows between cells through the plasmodesmata without crossing the plasma membrane.
In the transmembrane pathway, water moves across the plasma membranes, with a short visit to the cell wall space.
At the endodermis, the apoplast pathway is blocked by the Casparian strip.

39
Q

At the endodermis, water movement
through the apoplast pathway is
obstructed by the _____.

A

Casparian strip

40
Q

True or False

The Casparian strip breaks the continuity of the apoplast pathway. Hence, water movement across the endodermis occurs through the symplast.

A

True

41
Q

What are the factors that affect water absorption? (5)

A
  1. availability of soil water
  2. concentration of soil solution
  3. soil temperature
  4. soil aeration
  5. transpiration
42
Q

What are the factors that affect the rate of transpiration? (7)

A
  1. humidity of air
  2. temperature
  3. wind velocity
  4. light
  5. atmospheric pressure
  6. CO2 concentration
  7. root : shoot ratio
43
Q

Give some of the significance of transpiration. (3)

A
  1. it helps in the ascent of sap
  2. it helps in the absorption of water and minerals
  3. it has cooling effects
44
Q

____ occurs when water molecules are attracted to the walls of the vessel element.

A

adhesion

45
Q

____ occurs when water molecules are attracted to each other. As some water molecules move up the vessel element, they pull other water molecules with them.

A

cohesion

46
Q

True or False

Water molecules move up the xylem in MULTIPLE directions.

A

False

in ONE direction

47
Q

According to the ____, transpiration is the main driver of water movement in the xylem.

A

cohesion-tension theory

48
Q

True or False

Transpiration creates a POSITIVE pressure (TURGOR) equivalent to –2 MPa at the leaf surface.

A

False

NEGATIVE;
TENSION

49
Q

Give a 5 step-by-step process of transpiration.

A
  1. Water and minerals are absorbed by the roots of the plant from the soil.
  2. The water and minerals are transported up to the leaves through the xylem.
  3. The water evaporates from the leaves through the stomata, which are tiny openings on the leaf surface.
  4. The evaporation of water creates a negative pressure in the xylem.
  5. This negative pressure pulls water up from the roots through the xylem.
50
Q

____ was the first to suggest that the water flow in plants is governed by the C-T mechanism.

A

Stephen Hales

51
Q

What did Stephen Hales mean in his book, in which he wrote: “ for
without perspiration the [water]
must stagnate, notwithstanding the
sap-vessels are so curiously
adapted by their exceeding
fineness, to raise [water] to great
heights, in a reciprocal proportion
to their very minute diameters.”

A

Stephen Hales’s quote about transpiration can be summarized as follows:

Transpiration is essential for the upward movement of water in plants, even though the xylem vessels are very narrow. Without transpiration, the water would pool in the roots of the plant.

52
Q

___ is the damage that occurs to plant tissues when they freeze.

A

freezing injury

53
Q

What happens when water freezes in a plant cell?

A

The sharp ice crystals cut cell membranes, resulting in fluids leaking from the cell, leading to cell and plant death.

54
Q

What are some symptoms of freezing injury? (4)

A
  1. tissue browning
  2. tissue blackening
  3. tissue wilting, or
  4. curling of leaves and stems
55
Q

____ is the damage that occurs to plant tissues when they are exposed to temperatures above freezing but below a critical threshold temperature.

A

chilling injury

56
Q

In what threshold temperature does chilling injury occur?

A

from 32 to 55 F (0 to 10 C)

57
Q

True or False

Plants from temperate zones are often chilling sensitive, while most tropical origins are not.

A

False

Plants from tropical origins are often chilling-sensitive, while most temperate zone species are not.

58
Q

How do plants survive winter? (4)

A
  1. they create an anti-freeze
  2. they move water deeper
  3. they enter dormancy
  4. they drop their leaves

BIO107 General Physiology Lecture (5 decks)

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