Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

IB Biology > 9.1 Transport in the xylem of plants > Flashcards

9.1 Transport in the xylem of plants Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is transpiration?

A

Transpiration is the loss of water vapour from the stems and leaves of plants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are stomata?

A

Stomata are pores on the underside of the leaf which facilitate gas exchange

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does light energy convert in transpiration?

A

Water in the leaves into vapour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What happens to the vapour after it has been converted from water?

A

It evaporates from the leaf via the stomata

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where is new water absorbed?

A

From the soil by the roots

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does the new water absorbed create?

A

A difference in pressure between the leaves and the roots

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

During transpiration, what has low pressure?

A

The leaves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

During transpiration, what has high pressure?

A

The roots

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What requires the stomata to be open?

A

Photosynthetic gas exchange

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What affects transpiration?

A

The levels of photosynthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is transpiration a consequence of?

A

Gas exchange in the leaf

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why does new water need to be absorbed during transpiration?

A

To replace the lost water from transpiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

When is water lost from the leaves?

A

When it is converted into vapour and diffuses out the stomata

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What happens to some of the light energy absorbed by leaves?

A

It is converted into heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What does the heat that was converted by light energy do?

A

Evaporates water within the spongy mesophyll

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

When the vapour diffuses out of the leaf what does it create?

A

A negative pressure gradient within the leaf

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does the negative pressure gradient within the leaf create?

A

A tension force in leaf cells which draws water from the xylem

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How is water pulled from the xylem under tension?

A

By the adhesive attraction between water and the leaf cell walls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the transpiration rate?

A

The amount of water lost from the leaves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What regulates the transpiration rate?

A

The opening and closing of the stomata

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How do guard cells cause the stomata to open?

A

By being on either side of the stomata and by becoming increasingly flaccid in response to cellular signals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What do dehydrated mesophyll cells release?

A

Plant hormone abscisic acid (ABA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

When do mesophyll cells release ABA?

A

When a plant begins to wilt from water stress

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What does abscisic acid trigger?

A

The efflux of potassium from guard cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What does the efflux of potassium from guard cells trigger?

A

Decease in water pressure within the cells (lose turgor)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What does lose turgor mean?

A

Decrease in water pressure within the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What does a loss of turgor cause?

A

The stomata to close as the guard cells become flaccid and block the opening

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

When will transpiration rates be highest?

A

When stomatal pores are open than when they are closed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Apart from photosynthesis what are other factors that affect transpiration rates?

A

Humidity
Temperature
Light intensity
Wind

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What are stomatal pores responsible for?

A

Gas exchange in the leaf

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

When a stoma is open it is…

A

Turgid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

When a stoma is closed it is…

A

Flaccid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is a transpiration stream?

A

The flow of water through the xylem from the roots to the leaf against gravity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What are the two key properties responsible for helping water ride through the xylem?

A

Cohesion and adhesion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is cohesion?

A

Cohesion is the force of attraction between two particles of the same substance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Are water molecules polar or non polar?

A

Polar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Why can water molecules form intermolecular accossiations?

A

Because water molecules are polar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is the type of bond water molecules form?

A

Hydrogen bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What does the cohesive property cause?

A

Water molecules to be dragged up the xylem towards the leaves in a continuous stream

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What is adhesion?

A

Adhesion is the force of attraction between two particles of different substances?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Why can the xylem wall form polar intermolecular associations with water molecules?

A

Because the xylem wall is polar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What are an example of the different substances in adhesion?

A

Xylem wall and water molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What are an example of the same substances in cohesion?

A

Water molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

How do water molecules move up the xylem by?

A

Capillary action

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What does water moving up via capillary action cause?

A

Water molecules pull inwards on the xylem wall which creates further tension

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What is the xylem? (function)

A

A specialised structure that functions to facilitate the movement of water throughout the plant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What is the xylem?
(Structurally)

A

It is a tube composed of dead hollow cells to allow the free movement of water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

Why is the movement of water in the xylem passive?

A

Because the cells are dead

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

How many directions does the movement of water flow in the xylem?

A

One direction only

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

What is the structure of the wall of the xylem?

A

The walls have thickened cellulose and reinforced by lignin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Why is the xylem wall thickened by cellulose and reinforced by lignin?

A

To provide strength as water is transported under tension

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

What does the cell wall of the xylem contain?

A

Numerous pores called pits

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

What do pits enable?

A

It enables water to be transferred between cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

What can xylems be composed of?

A

Tracheids or vessel elements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

What are all vascular plants composed of?

A

Tracheids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

What are only certain vascular plants composed of?

A

Vessel elements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

What are tracheids?

A

Tracheids are tapered cells that exchange water solely via pits

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

What do tracheids result in?

A

A slower rate of water transfer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

In vessel elements, what happens to the end walls?

A

The end walls have become fused to form a continuous tube

60
Q

What do vessel elements result in?

A

A faster rate of water transfer

61
Q

What are the two types of xylem vessels?

A

Annular vessels and spiral vessels

62
Q

How is lignin deposited in annular vessels?

A

In a pattern of circular rings that are equally distanced from each other

63
Q

How is lignin deposited in spiral vessels?

A

In the form of a helix or a coil

64
Q

What does the xylem conduct?

A

Water and minerals

65
Q

How do plants take up water and mineral ions via?

A

Via their roots

66
Q

What do roots need to optimise their uptake of water and mineral ions?

A

A maximal surface area

67
Q

What does a fibrous, highly branching root system do?

A

Increases the surface area available for absorption

68
Q

What does a main tap root with lateral branches do?

A

Penetrate the soil to access deeper reservoirs of water

69
Q

What will the epidermis of roots have?

A

Root hairs

70
Q

What do root hairs do?

A

Further increase the surface area for absorption

71
Q

What surrounds the steele?

A

An endodermis layer that is impermeable to the passive flow of water and ions

72
Q

What pumps water and minerals across the barrier?

A

Specialised cells

73
Q

What do the specialised cells allow?

A

The rate of uptake to be controlled

74
Q

Where do materials absorbed by the root epidermis diffuse to?

A

Across the cortex towards a central stele

75
Q

What is found in the central stele?

A

The xylem

76
Q

What does fertile soil typically contain?

A

Negatively charged clay particles

77
Q

What can attach to negatively charged clay particles?

A

Positively charged mineral ions

78
Q

What are five examples of minerals that need to be uptaken from the soil?

A

Mg2+
nitrates
Na+
K+
PO43–

79
Q

How are mineral ions diffused into the roots?

A

Passively

80
Q

How are minerals transported up the xylem?

A

Actively by indirect active transport

81
Q

What do root cells contain?

A

Proton pumps

82
Q

What do the proton pumps in root cells do?

A

Actively expel H+ ions into the surrounding soil

83
Q

What do the H+ ions displace?

A

They displace the positively charged mineral ions from the clay

84
Q

What does displacing the positively charged mineral ions from the clay do?

A

Allows them to diffuse into the root along a gradient

85
Q

What may negatively charged mineral ions bind to and what happens?

A

H+ ions and they are then reabsorbed with the proton

86
Q

What follows mineral ions into the root?

A

Water

87
Q

How does water follow mineral ions into the root?

A

Via osmosis

88
Q

Why dpes water move into the root via osmosis?

A

Its moving towards the region with a higher solute concentration

89
Q

What regulates the rate of water uptake?

A

Specialised water channels called aquaporins on the root cell membrane

90
Q

Once water is inside the root how will water move towards the xylem?

A

Via the cytoplasm or via the cell wall

91
Q

If the water moves via the cytoplasm what is it called?

A

Symplastic

92
Q

If the water moves via the cell wall what is it called?

A

Apoplastic

93
Q

What happens in the symplastic pathway?

A

Water moves continuously through the cytoplasm of cells

94
Q

What happens in the apoplastic pathway?

A

Water cannot cross the casparian strip and is transferred to the cytoplasm of the endodermis

95
Q

How are the cytoplasm of cells connected?

A

Via plasmodesmata

96
Q

When drawing the structure of the xylem, how should vessel elements be drawn?

A

As a continuous tube

97
Q

When drawing the structure of the xylem, how should the remnants of the fused end wall be represented as?

A

Indents

98
Q

When drawing the structure of the xylem, what should the xylem wall contain?

A

Gaps

99
Q

When drawing the structure of the xylem, how should lignin be represented?

A

As either a spiral or rings

100
Q

What are xerophytes?

A

Desert plants

101
Q

What are halophytes?

A

Plants that grow in high salinity

102
Q

Why will xerophytes have high rates of transpiration?

A

Due to high temperatures and low humidity of the desert environments

103
Q

Why will halophytes lose water?

A

Due to the high intake of salt from the surrounding soils draw water from the plant tissue

104
Q

What are the six adaptations xerophytes have?

A

Reduced Leaves
Rolled Leaves
Thick waxy cuticle
Stomata in pits
Low growth
CAM physiology

105
Q

How does reduced leaves help xerophytes?

A

Reducing the number and size of the leaves reduces the surface area for water loss

106
Q

How does rolled leaves help xerophytes?

A

Rolling up leaves reduces the exposure stomata have to the air thus reducing evaporative water loss

107
Q

How does thick waxy cuticles help xerophytes?

A

Having leaves covered by a thickened cuticle prevents water loss from the leaf surface

108
Q

How does stomata in pits help xerophytes?

A

Having stomata in pits and surrounded by hair traps water vapour and reduces transpiration

109
Q

How does low growth help xerophytes?

A

Low growing plants are less exposed to wind and are more likely to be shaded which reduces water loss

110
Q

How does CAM physiology help xerophytes?

A

Plants with CAM physiology open their stomata at night, reducing water loss via evaporation

111
Q

What are the five adaptations halophytes will have?

A

Cellular sequestration
Tissue Partitioning
Root level exclusion
Salt excretion
Altered flowering schedule

112
Q

How does cellular sequestration help halophytes?

A

Halophytes can sequester toxic ions and salts within the cell wall or vacuoles

113
Q

How does tissue partitioning help halophytes?

A

Plants may concentrate cells in particular leaves which then drop off

114
Q

How does root level exclusion help halophytes?

A

Plant roots may be structured to exclude 95% if the salt in the soil solutions

115
Q

How does salt excretion help halophytes?

A

Certain parts of the plant may contain salt glands which actively eliminate salt

116
Q

How does altered flowering schedule help halophytes?

A

Halophytes may flower at specific times to minimise salt exposure

117
Q

What are the three apparatus used to model the movement of water up the length of the xylem?

A

Capillary tubing
Filter paper
Porous pots

118
Q

Why does water have to capacity to flow along narrow spaces?

A

Due to a combination of surface tension and adhesion with the walls

119
Q

What does capillary tubing show?

A

The thinner the tube or the less dense the fluid, the higher the liquid will rise

120
Q

How does filter paper work?

A

Filter paper absorbs water due to both adhesive and cohesive properties

121
Q

What happens when filter paper is placed perpendicular to the water source?

A

The water will rise up along the length of the paper

122
Q

What does water rising along the length of the filter paper compare to?

A

The movement of water up a xylem

123
Q

What is filter paper made of?

A

Cellulose

124
Q

What are porous pots?

A

Porous pots are semi permeable containers that allow the free passage of certain materials through pores

125
Q

What is the loss of water from porous pots similar to?

A

It is similar to the evaporative water loss that occurs in the leaves of the plants

126
Q

What happens if the porous pot is attached by an airtight seal to a tube?

A

The water loss creates a negative pressure which brings in more liquid

127
Q

What is a potometer?

A

A potometer is a device that is used to estimate transpiration rates by measuring the rate of water gain/loss

128
Q

What is shown when a plant is affixed to a potometer?

A

Transpiration is shown by the movement of water towards the plant

129
Q

How can water movement in a potometer be assessed?

A

By a change in meniscus level or by the movement of an air bubble towards the plant

130
Q

What can alter the initial starting point of the meniscus or air bubble in a potometer?

A

Adding additional water

131
Q

What is important to remember when measuring transpiration rates with a potometer?

A

Not all water is lost to transpiration

132
Q

If not all water is lost to transpiration where else is it lost?

A

To photosynthesis and to maintain the viable turgidity of plant cells

133
Q

What can potometers be used to test?

A

Variables that may affect the rate of transpiration in plants

134
Q

What are the variables potometers can measure?

A

Temperature
Humidity
Light intensity
Wind exposure

135
Q

What does increasing the temperature do to the rate of transpiration?

A

Increases the rate of transpiration

136
Q

How can you test temperature using a potometer?

A

With a heater or a heated water bath

137
Q

How do higher temperatures lead to more evaporation?

A

It increases the rate of water vaporisation within the mesophyll

138
Q

What does increasing the humidity do to the rate of transpiration?

A

Decreases the rate of transpiration

139
Q

What is humidity?

A

Humidity is the amount of water vapour in the air

140
Q

How can you test humidity using a potometer?

A

By encasing the plant in a plastic bag with variable levels of vapour

141
Q

How does humidity affect the amount of vapour diffused out of a leaf?

A

Less vapour will diffuse from the leaf if there is more vapour in the air

142
Q

How does increasing light intensity affect the rate of transpiration?

A

It causes an increase in the rate of transpiration

143
Q

What does increasing light exposure do?

A

Increasing light exposure causes more stomata open in order to facilitate photosynthetic gas exchange

144
Q

How can you test light exposure using a potometer?

A

By placing a plant at variable distances from a lamp

145
Q

How does increasing the level of wind exposure affect the rate of transpiration?

A

It increases the rate of transpiration

146
Q

How does increasing wind exposure reduce proximal humidity?

A

Wind removes water vapour from near the lead reducing proximal humidity

147
Q

How can you test wind exposure with a potometer?

A

By using fans

IB Biology (57 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions