6.5: Limiting water loss Flashcards

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1
Q

The features that make a good gas exchange system are the same features that do what?

A

The features that make a good gas exchange system are the same features that increase water loss

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2
Q

The features that make a good gas exchange system are the same features that increase water loss.
In order to survive, what does terrestrial organisms do?

A

In order to survive, terrestrial organisms must limit their water loss without compromising the efficiency of their gas exchange systems

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3
Q

Examples of terrestrial organisms

A

Examples of terrestrial organisms are:

  1. Insects
  2. Plants
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4
Q

Most insects are terrestrial (do what)?

A

Most insects are terrestrial (live on land)

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5
Q

Most insects are terrestrial (live on land).
The problem for all terrestrial organisms is that water easily evaporates from the surface of their bodies and they can become dehydrated.
They have evolved adaptations to conserve water.
However, efficient gas exchange requires a thin, permeable surface with a large area.
What do these features conflict with?

A

These features conflict with the need to conserve water

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6
Q

Insects have evolved the following adaptations that reduce water loss, what?

A

Insects have evolved the following adaptations that reduce water loss:

  1. A small SA:V ratio
  2. Waterproof coverings over their body surfaces
  3. Spiracles
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7
Q

Insects have evolved the following adaptations that reduce water loss - A small SA:V ratio, waterproof coverings over the body surfaces and spiracles.
1. A small SA:V ratio to do what?

A

A small SA:V ratio to minimise the area over which water is lost

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8
Q

Insects have evolved the following adaptations that reduce water loss - A small SA:V ratio, waterproof coverings over the body surfaces and spiracles.
1. A small SA:V ratio to minimise the area over which water is lost.
2. Waterproof coverings over their body surfaces.
In the case of insects, what is this covering?

A

In the case of insects, this covering is a rigid outer skeleton of chitin

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9
Q

Insects have evolved the following adaptations that reduce water loss - A small SA:V ratio, waterproof coverings over the body surfaces and spiracles.
1. A small SA:V ratio to minimise the area over which water is lost.
2. Waterproof coverings over their body surfaces.
In the case of insects, this covering is a rigid outer skeleton of chitin that is covered with what?

A

In the case of insects, this covering is a rigid outer skeleton of chitin that is covered with a waterproof cuticle

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10
Q

Insects have evolved the following adaptations that reduce water loss - A small SA:V ratio, waterproof coverings over the body surfaces and spiracles.
1. A small SA:V ratio to minimise the area over which water is lost.
2. Waterproof coverings over their body surfaces.
In the case of insects, this covering is a rigid outer skeleton of chitin that is covered with a waterproof cuticle.
3. Spiracles are the openings of the tracheae at the body surface and these can be closed to reduce water loss.
What does this conflict with?

A

This conflicts with the need for oxygen

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11
Q

Insects have evolved the following adaptations that reduce water loss - A small SA:V ratio, waterproof coverings over the body surfaces and spiracles.
1. A small SA:V ratio to minimise the area over which water is lost.
2. Waterproof coverings over their body surfaces.
In the case of insects, this covering is a rigid outer skeleton of chitin that is covered with a waterproof cuticle.
3. Spiracles are the openings of the tracheae at the body surface and these can be closed to reduce water loss.
This conflicts with the need for oxygen and so largely occurs when?

A

This:

  1. Conflicts with the need for oxygen
  2. So largely occurs when the insect is at rest
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12
Q

Insects have evolved the following adaptations that reduce water loss - A small SA:V ratio, waterproof coverings over the body surfaces and spiracles.
1. A small SA:V ratio to minimise the area over which water is lost.
2. Waterproof coverings over their body surfaces.
In the case of insects, this covering is a rigid outer skeleton of chitin that is covered with a waterproof cuticle.
3. Spiracles are the openings of the tracheae at the body surface and these can be closed to reduce water loss.
This conflicts with the need for oxygen and so largely occurs when the insect is at rest.
These features mean that insects cannot use the body surface to diffuse respiratory gases in the way a single-celled organism does.
Instead, they have an internal network of tubes called tracheae that carry air containing oxygen directly to what?

A

Instead, they have an internal network of tubes called tracheae that carry air containing oxygen directly to the muscle tissues

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13
Q

While plants also have waterproof coverings, they cannot have a small SA:V ratio.
Why is this?

A

This is because:

  1. Plants photosynthesise
  2. Photosynthesis requires a large leaf surface area for the capture of light and for the exchange of gases
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14
Q

Xerophytes

A

Xerophytes are plants that are adapted to living in:

  1. Hot and dry environments
  2. Areas where water is in short supply
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15
Q

Xerophytes are plants that are adapted to living in hot and dry environments and in areas where water is in short supply.
Without these adaptations, what would happen to these plants?

A

Without these adaptations, these plants would:

  1. Become desiccated
  2. Die
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16
Q

What has leaves with a thick waxy cuticle that reduces water loss?

A

Holly has leaves with a thick waxy cuticle that reduces water loss

17
Q

What have needle-like leaves to reduce water loss?

A

Conifers have needle-like leaves to reduce water loss

18
Q

Xerophytes have special adaptations to reduce the rate of transpiration:
1. Reduced leaf area as what?

A

Reduced leaf area as the leaves are reduced to spines

19
Q

Xerophytes have special adaptations to reduce the rate of transpiration:

  1. Reduced leaf area as the leaves are reduced to spines.
  2. What to hold water?
A

Thick, fleshy stems to hold water

20
Q

Xerophytes have special adaptations to reduce the rate of transpiration:

  1. Reduced leaf area as the leaves are reduced to spines.
  2. Thick, fleshy stems to hold water.
  3. What to reflect the Sun?
A

A silver surface to reflect the Sun

21
Q

What is the scientific name for cacti?

A

Xerophytes is the scientific name for cacti

22
Q

The main way of surviving in habitats where there is a high rate of water loss and a limited water supply is to reduce the rate at which water can be lost through evaporation.
As the vast majority of water loss occurs through the leaves, it is these organs that usually show most modifications.
What do examples of these modifications include?

A

Examples of these modifications include:

  1. A very thick waxy cuticle to reduce evaporation
  2. Rolling up of leaves
  3. Hairy leaves
  4. Stomata in pits or grooves
  5. A reduced SA:V ratio of the leaves
23
Q

The main way of surviving in habitats where there is a high rate of water loss and a limited water supply is to reduce the rate at which water can be lost through evaporation.
As the vast majority of water loss occurs through the leaves, it is these organs that usually show most modifications.
Examples of these modifications include a very thick waxy cuticle to reduce evaporation, rolling up of leaves, hairy leaves, stomata in pits or grooves and a reduced SA:V ratio of the leaves.
1. A very thick waxy cuticle to reduce evaporation:
Although the waxy cuticle on leaves forms a waterproof barrier, up to 10% of water loss can still occur by this route.
The thicker the cuticle, what?

A

The thicker the cuticle, the less water can escape by this means

24
Q

The main way of surviving in habitats where there is a high rate of water loss and a limited water supply is to reduce the rate at which water can be lost through evaporation.
As the vast majority of water loss occurs through the leaves, it is these organs that usually show most modifications.
Examples of these modifications include a very thick waxy cuticle to reduce evaporation, rolling up of leaves, hairy leaves, stomata in pits or grooves and a reduced SA:V ratio of the leaves.
1. A very thick waxy cuticle to reduce evaporation:
Although the waxy cuticle on leaves forms a waterproof barrier, up to 10% of water loss can still occur by this route.
The thicker the cuticle, the less water can escape by this means, for example what?

A

The thicker the cuticle, the less water can escape by this means, for example holly

25
Q

The main way of surviving in habitats where there is a high rate of water loss and a limited water supply is to reduce the rate at which water can be lost through evaporation.
As the vast majority of water loss occurs through the leaves, it is these organs that usually show most modifications.
Examples of these modifications include a very thick waxy cuticle to reduce evaporation, rolling up of leaves, hairy leaves, stomata in pits or grooves and a reduced SA:V ratio of the leaves.
2. Rolling up of leaves:
What does the rolling up of leaves do?

A

The rolling up of leaves:

  1. Reduces the area exposed to the air
  2. Keeps the stomata on the inside
26
Q

The main way of surviving in habitats where there is a high rate of water loss and a limited water supply is to reduce the rate at which water can be lost through evaporation.
As the vast majority of water loss occurs through the leaves, it is these organs that usually show most modifications.
Examples of these modifications include a very thick waxy cuticle to reduce evaporation, rolling up of leaves, hairy leaves, stomata in pits or grooves and a reduced SA:V ratio of the leaves.
2. Rolling up of leaves:
The rolling up of leaves reduces the area exposed to the air and keeps the stomata on the inside, so increasing what?

A

The rolling up of leaves:
1. Reduces the area exposed to the air
2. Keeps the stomata on the inside
,so increasing the water vapour inside the roll

27
Q

The main way of surviving in habitats where there is a high rate of water loss and a limited water supply is to reduce the rate at which water can be lost through evaporation.
As the vast majority of water loss occurs through the leaves, it is these organs that usually show most modifications.
Examples of these modifications include a very thick waxy cuticle to reduce evaporation, rolling up of leaves, hairy leaves, stomata in pits or grooves and a reduced SA:V ratio of the leaves.
2. Rolling up of leaves:
The rolling up of leaves reduces the area exposed to the air and keeps the stomata on the inside, so increasing the water vapour inside the roll.
What does increasing the water vapour around the stomata do?

A

Increasing the water vapour around the stomata reduces the water potential gradient

28
Q

The main way of surviving in habitats where there is a high rate of water loss and a limited water supply is to reduce the rate at which water can be lost through evaporation.
As the vast majority of water loss occurs through the leaves, it is these organs that usually show most modifications.
Examples of these modifications include a very thick waxy cuticle to reduce evaporation, rolling up of leaves, hairy leaves, stomata in pits or grooves and a reduced SA:V ratio of the leaves.
2. Rolling up of leaves:
The rolling up of leaves reduces the area exposed to the air and keeps the stomata on the inside, so increasing the water vapour inside the roll.
Increasing the water vapour around the stomata reduces the water potential gradient and so does what?

A

Increasing the water vapour around the stomata:

  1. Reduces the water potential gradient
  2. So slows water loss
29
Q

The main way of surviving in habitats where there is a high rate of water loss and a limited water supply is to reduce the rate at which water can be lost through evaporation.
As the vast majority of water loss occurs through the leaves, it is these organs that usually show most modifications.
Examples of these modifications include a very thick waxy cuticle to reduce evaporation, rolling up of leaves, hairy leaves, stomata in pits or grooves and a reduced SA:V ratio of the leaves.
3. Hairy leaves:
A thick layer of hairs on leaves, especially on the what, traps what air next to the leaf surface?

A
A thick layer of hairs on leaves, especially on the lower epidermis, traps:
1. Still
2. Moist
3. Saturated
air next to the leaf surface
30
Q

The main way of surviving in habitats where there is a high rate of water loss and a limited water supply is to reduce the rate at which water can be lost through evaporation.
As the vast majority of water loss occurs through the leaves, it is these organs that usually show most modifications.
Examples of these modifications include a very thick waxy cuticle to reduce evaporation, rolling up of leaves, hairy leaves, stomata in pits or grooves and a reduced SA:V ratio of the leaves.
3. Hairy leaves:
A thick layer of hairs on leaves, especially on the lower epidermis, traps still, moist, saturated air next to the leaf surface.
What is reduced?

A

The water potential gradient between:
1. The inside
2. The outside
of the leaves is reduced

31
Q

The main way of surviving in habitats where there is a high rate of water loss and a limited water supply is to reduce the rate at which water can be lost through evaporation.
As the vast majority of water loss occurs through the leaves, it is these organs that usually show most modifications.
Examples of these modifications include a very thick waxy cuticle to reduce evaporation, rolling up of leaves, hairy leaves, stomata in pits or grooves and a reduced SA:V ratio of the leaves.
3. Hairy leaves:
A thick layer of hairs on leaves, especially on the lower epidermis, traps still, moist, saturated air next to the leaf surface.
The water potential gradient between the inside and the outside of the leaves is reduced and therefore what?

A

The water potential gradient between:
1. The inside
2. The outside
of the leaves is reduced and therefore less water is lost by evaporation

32
Q

The main way of surviving in habitats where there is a high rate of water loss and a limited water supply is to reduce the rate at which water can be lost through evaporation.
As the vast majority of water loss occurs through the leaves, it is these organs that usually show most modifications.
Examples of these modifications include a very thick waxy cuticle to reduce evaporation, rolling up of leaves, hairy leaves, stomata in pits or grooves and a reduced SA:V ratio of the leaves.
3. Hairy leaves:
A thick layer of hairs on leaves, especially on the lower epidermis, traps still, moist, saturated air next to the leaf surface.
The water potential gradient between the inside and the outside of the leaves is reduced and therefore less water is lost by evaporation.
What plant has this modification?

A

One type of heather plant has this modification

33
Q

The main way of surviving in habitats where there is a high rate of water loss and a limited water supply is to reduce the rate at which water can be lost through evaporation.
As the vast majority of water loss occurs through the leaves, it is these organs that usually show most modifications.
Examples of these modifications include a very thick waxy cuticle to reduce evaporation, rolling up of leaves, hairy leaves, stomata in pits or grooves and a reduced SA:V ratio of the leaves.
4. Stomata in pits or grooves.
What do stomata in pits or grooves do?

A

Stomata in pits or grooves again:

  1. Trap still, moist air next to the leaf
  2. Become saturated or sunken
  3. Reduce the water potential gradient
34
Q

The main way of surviving in habitats where there is a high rate of water loss and a limited water supply is to reduce the rate at which water can be lost through evaporation.
As the vast majority of water loss occurs through the leaves, it is these organs that usually show most modifications.
Examples of these modifications include a very thick waxy cuticle to reduce evaporation, rolling up of leaves, hairy leaves, stomata in pits or grooves and a reduced SA:V ratio of the leaves.
4. Stomata in pits or grooves.
Stomata in pits or grooves again trap still, moist air next to the leaf, become saturated or sunken and reduce the water potential gradient.
Examples of plants using this mechanism include what?

A

Examples of plants using this mechanism include pine trees

35
Q

The main way of surviving in habitats where there is a high rate of water loss and a limited water supply is to reduce the rate at which water can be lost through evaporation.
As the vast majority of water loss occurs through the leaves, it is these organs that usually show most modifications.
Examples of these modifications include a very thick waxy cuticle to reduce evaporation, rolling up of leaves, hairy leaves, stomata in pits or grooves and a reduced SA:V ratio of the leaves.
5. A reduced SA:V ratio of the leaves.
The smaller the SA:V ratio, the slower the rate of diffusion.
By having leaves that are what, rather than leaves that are what, the rate of water loss can be considerably reduced?

A

By having:
1. Leaves that are small and roughly circular in cross-section
,rather than
2. Leaves that are broad and flat
,the rate of water loss can be considerably reduced

36
Q

The main way of surviving in habitats where there is a high rate of water loss and a limited water supply is to reduce the rate at which water can be lost through evaporation.
As the vast majority of water loss occurs through the leaves, it is these organs that usually show most modifications.
Examples of these modifications include a very thick waxy cuticle to reduce evaporation, rolling up of leaves, hairy leaves, stomata in pits or grooves and a reduced SA:V ratio of the leaves.
5. A reduced SA:V ratio of the leaves.
The smaller the SA:V ratio, the slower the rate of diffusion.
By having leaves that are small and roughly circular in cross-section, rather than leaves that are broad and flat, the rate of water loss can be considerably reduced.
Examples

A

For example:

  1. Spines
  2. Pine needles
37
Q

What does climate change affect?

A

Climate change affects:

  1. Rainfall
  2. The rate of evaporation of water
38
Q

Climate change affects rainfall and the rate of evaporation of water.
As a result, what changes?

A

As a result, the distribution of plant species changes

39
Q

Climate change affects rainfall and the rate of evaporation of water.
As a result, the distribution of plant species changes.
As regions become drier, so what increases?

A

As regions become drier, so the number of xerophytic plants in them increases