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SAJID A Level AQA Biology > 6.4: Gas exchange in the leaf of a plant > Flashcards

6.4: Gas exchange in the leaf of a plant Flashcards

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1
Q

Upper epidermis

A

The upper epidermis is a protection layer from any kind of damage

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2
Q

The upper epidermis is a protection layer from any kind of damage. What does the upper epidermis do?

A

The upper epidermis protects the internal tissues from:

  1. Mechanical damage
  2. Bacterial and fungal invasion
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3
Q

Cuticle

A

The cuticle is a waxy layer that prevents water loss from the leaf surface

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4
Q

What does the palisade mesophyll layer contain?

A

The palisade mesophyll layer contains many chloroplasts

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5
Q

The palisade mesophyll layer contains many chloroplasts.

Describe the palisade mesophyll cells

A

The palisade mesophyll cells are columnar cells that are closely packed together to absorb light more efficiently

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6
Q

What allows gases to move in and out of the leaf?

A

The spongy mesophyll layer allows gases to move:

  1. In
  2. Out of

the leaf

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7
Q

Spongy mesophyll layer

A

The spongy mesophyll layer is irregular cells loosely packed together to leave numerous large air spaces to allow rapid diffusion of gases throughout the leaf

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8
Q

Lower epidermis

A

The lower epidermis is the same as the upper epidermis, except the cuticle is thinner

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9
Q

The lower epidermis is the same as the upper epidermis, except the cuticle is thinner.

Why is the cuticle thinner?

A

The cuticle is thinner, because it’s on the bottom of the leaf

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10
Q

The lower epidermis is the same as the upper epidermis, except the cuticle is thinner.

The cuticle is thinner, because it’s on the bottom of the leaf and therefore it is what?

A

The cuticle is thinner, because it’s on the bottom of the leaf and therefore it is less exposed to the Sun

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11
Q

The lower epidermis is the same as the upper epidermis, except the cuticle is thinner.

The cuticle is thinner, because it’s on the bottom of the leaf and therefore it is less exposed to the Sun, so what?

A

The cuticle is thinner, because it’s on the bottom of the leaf and therefore it is less exposed to the Sun, so there will be less evaporation

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12
Q

Stomata

A

The stomata are an opening that allows gases to pass through it to go:

  1. Into

Or,

  1. Out of the leaf
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13
Q

The stomata are an opening that allows gases to pass through it to go into or out of the leaf.

What do stomata also do?

A

Stomata also let water out during respiration

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14
Q

The stomata are an opening that allows gases to pass through it to go into or out of the leaf.

Stomata also let water out during respiration.

What is this process called?

A

This process is called transpiration

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15
Q

What is the vascular bundle (vein) made up of?

A

The vascular bundle (vein) is made up of:

  1. Xylem
  2. Phloem
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16
Q

What is the function of xylem?

A

The function of xylem is to transport:

  1. Water
  2. Mineral salts

towards the leaf

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17
Q

What is the function of phloem?

A

The function of phloem is to transport organic substances away from the leaf

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18
Q

The function of phloem is to transport organic substances away from the leaf.

What does phloem generally transport?

A

Phloem generally transports sucrose

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19
Q

What do guard cells do?

A

Guard cells control the:

  1. Opening
  2. Closing

of the stomata

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20
Q

What do guard cells have?

A

Guard cells have a:

  1. Thin outer wall
  2. Thick, inelastic inner wall
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21
Q

Guard cells have a thin outer wall and a thick, inelastic inner wall.

What is the thick, inelastic inner wall fundamental for?

A

The thick, inelastic inner wall is fundamental for movement

22
Q

When the guard cells are flaccid (lack of water), what are the stoma?

A

When the guard cells are flaccid (lack of water), the stoma are closed

23
Q

When the guard cells are turgid (plenty of water), what are the stoma?

A

When the guard cells are turgid (plenty of water), the stoma are open

24
Q

When the guard cells are turgid (plenty of water), the stoma are open, why?

A

When the guard cells are turgid (plenty of water), the stoma are open, because the inside thick, inelastic wall doesn’t open as much as it should

25
Q

When the guard cells are turgid (plenty of water), the stoma are open, because the inside thick, inelastic wall doesn’t open as much as it should, so what is there?

A

When the guard cells are turgid (plenty of water), the stoma are open, because the inside thick, inelastic wall doesn’t open as much as it should, so there is a hole

26
Q

How many parts does photosynthesis have?

A

Photosynthesis has 2 parts, a:

  1. Light-dependent part
  2. Light-independent part
27
Q

Stomatal opening over 24 hours:

When do the stomata begin to open?

A

The stomata begin to open at dawn

28
Q

Stomatal opening over 24 hours:

The stomata begin to open at dawn.

What does the increased light intensity cause?

A

The increased light intensity causes more stomata to open

29
Q

Stomatal opening over 24 hours:

The stomata begin to open at dawn.

The increased light intensity causes more stomata to open.

When do some plants close stomata?

A

Some plants close stomata during the hottest weather

30
Q

Stomatal opening over 24 hours:

The stomata begin to open at dawn.

The increased light intensity causes more stomata to open.

Some plants close stomata during the hottest weather.

This is an adaptation for what environments?

A

This is an adaptation for hot, dry environments

31
Q

Stomatal opening over 24 hours:

The stomata begin to open at dawn.

The increased light intensity causes more stomata to open.

Some plants close stomata during the hottest weather.

This is an adaptation for hot, dry environments.

When do stomata close?

A

Stomata close as the sun sets

32
Q

Stomata are closed when there isn’t much what in the guard cells?

A

Stomata are closed when there isn’t much water in the guard cells

33
Q

Stomata are closed when there isn’t much water in the guard cells.

How does water get inside the guard cells?

A

Water gets inside the guard cells by osmosis

34
Q

Stomata are closed when there isn’t much water in the guard cells.

Water gets inside the guard cells by osmosis.

The guard cells become what and, because of what, they do what?

A

The guard cells:

  1. Become turgid
  2. Because of their thick, inelastic inner wall, they curve and open the stomata
35
Q

Stomata are closed when there isn’t much water in the guard cells.

Water gets inside the guard cells by osmosis.

The guard cells become turgid and ,because of their thick, inelastic inner wall, they curve and open the stomata.

What is this process influenced by?

A

This process is influenced by:

  1. Water availability
  2. Carbon dioxide concentration
  3. Light intensity
36
Q

What does the mesophyll layer consist of?

A

The mesophyll layer consists of 2 parts, the:

  1. Palisade mesophyll layer
  2. Spongy mesophyll layer
37
Q

When photosynthesis is not occurring, in the dark, for example, why does oxygen diffuse into the leaf?

A

When photosynthesis is not occurring, in the dark, for example, oxygen diffuses into the leaf, because it is constantly being used by cells during respiration

38
Q

When photosynthesis is not occurring, in the dark, for example, oxygen diffuses into the leaf, because it is constantly being used by cells during respiration.

In the same way, carbon dioxide produced when does what?

A

In the same way, carbon dioxide produced during respiration diffuses out of the leaf

39
Q

How are the diffusion gradients in and out of the leaf maintained?

A

The diffusion gradients in and out of the leaf are maintained by:

  1. Mitochondria carrying out respiration
  2. Chloroplasts carrying out photosynthesis
40
Q

The structure of a plant leaf and gas exchange:

In some ways, gas exchange in plants is similar to that of insects, how?

A

In some ways, gas exchange in plants is similar to that of insects:

  1. No living cell is far from the external air and therefore a source of oxygen and carbon dioxide
  2. Diffusion takes place in the gas phase (air)
41
Q

The structure of a plant leaf and gas exchange:

In some ways, gas exchange in plants is similar to that of insects - No living cell is far from the external air and therefore a source of oxygen and carbon dioxide and diffusion takes place in the gas phase (air), which does what?

A

In some ways, gas exchange in plants is similar to that of insects:

  1. No living cell is far from the external air and therefore a source of oxygen and carbon dioxide
  2. Diffusion takes place in the gas phase (air), which makes it more rapid than if it were in water
42
Q

The structure of a plant leaf and gas exchange:

In some ways, gas exchange in plants is similar to that of insects - No living cell is far from the external air and therefore from a source of oxygen and carbon dioxide and diffusion takes place in the gas phase (air), which makes it more rapid than if it were in water.

Overall, therefore, there is a short, fast diffusion pathway.

In addition, what do the air spaces inside a leaf have compared with what?

A

In addition, the air spaces inside a leaf have a very large surface area compared with the volume of living tissue

43
Q

The structure of a plant leaf and gas exchange:

In some ways, gas exchange in plants is similar to that of insects - No living cell is far from the external air and therefore from a source of oxygen and carbon dioxide and diffusion takes place in the gas phase (air), which makes it more rapid than if it were in water.

Overall, therefore, there is a short, fast diffusion pathway.

In addition, the air spaces inside a leaf have a very large surface area compared with the volume of living tissue.

There is no specific transport system for gases, which simply move in and through the plant by diffusion.

Most gaseous exchange occurs in the leaves, which show the following adaptations for rapid diffusion:

  1. Many small pores, called stomata, and so no cell is far from what and therefore what is short?
A

Many small pores, called stomata, and so no cell is far from a stoma and therefore the diffusion pathway is short

44
Q

The structure of a plant leaf and gas exchange:

In some ways, gas exchange in plants is similar to that of insects - No living cell is far from the external air and therefore from a source of oxygen and carbon dioxide and diffusion takes place in the gas phase (air), which makes it more rapid than if it were in water.

Overall, therefore, there is a short, fast diffusion pathway.

In addition, the air spaces inside a leaf have a very large surface area compared with the volume of living tissue.

There is no specific transport system for gases, which simply move in and through the plant by diffusion.

Most gaseous exchange occurs in the leaves, which show the following adaptations for rapid diffusion:

  1. Many small pores, called stomata, and so no cell is far from a stoma and therefore the diffusion pathway is short.
  2. Numerous what that occur throughout the mesophyll layer?
A

Numerous interconnecting air spaces that occur throughout the mesophyll layer

45
Q

The structure of a plant leaf and gas exchange:

In some ways, gas exchange in plants is similar to that of insects - No living cell is far from the external air and therefore from a source of oxygen and carbon dioxide and diffusion takes place in the gas phase (air), which makes it more rapid than if it were in water.

Overall, therefore, there is a short, fast diffusion pathway.

In addition, the air spaces inside a leaf have a very large surface area compared with the volume of living tissue.

There is no specific transport system for gases, which simply move in and through the plant by diffusion.

Most gaseous exchange occurs in the leaves, which show the following adaptations for rapid diffusion:

  1. Many small pores, called stomata, and so no cell is far from a stoma and therefore the diffusion pathway is short.
  2. Numerous interconnecting air spaces that occur throughout the mesophyll layer, why?
A

Numerous interconnecting air spaces that occur throughout the mesophyll layer, so that gases can readily come into contact with the mesophyll cells

46
Q

The structure of a plant leaf and gas exchange:

In some ways, gas exchange in plants is similar to that of insects - No living cell is far from the external air and therefore from a source of oxygen and carbon dioxide and diffusion takes place in the gas phase (air), which makes it more rapid than if it were in water.

Overall, therefore, there is a short, fast diffusion pathway.

In addition, the air spaces inside a leaf have a very large surface area compared with the volume of living tissue.

There is no specific transport system for gases, which simply move in and through the plant by diffusion.

Most gaseous exchange occurs in the leaves, which show the following adaptations for rapid diffusion:

  1. Many small pores, called stomata, and so no cell is far from a stoma and therefore the diffusion pathway is short.
  2. Numerous interconnecting air spaces that occur throughout the mesophyll layer, so that gases can readily come into contact with the mesophyll cells.
  3. What of mesophyll cells for rapid diffusion?
A

A large surface area of mesophyll cells for rapid diffusion

47
Q

Stomata are minute pores that occur where?

A

Stomata are minute pores that occur:

  1. Mainly

,but

  1. Not exclusively

,on the leaves

48
Q

Stomata are minute pores that occur mainly, but not exclusively, on the leaves, especially the what?

A

Stomata are minute pores that occur:

  1. Mainly

,but

  1. Not exclusively

,on the leaves, especially the underside

49
Q

Stomata are minute pores that occur mainly, but not exclusively, on the leaves, especially the underside.

What is each stoma (singular) surrounded by?

A

Each stoma (singular) is surrounded by a pair of special cells, guard cells

50
Q

Stomata are minute pores that occur mainly, but not exclusively, on the leaves, especially the underside.

Each stoma (singular) is surrounded by a pair of special cells, guard cells.

What can these guard cells open and close?

A

These guard cells can:

  1. Open
  2. Close

the stomatal pore

51
Q

Stomata are minute pores that occur mainly, but not exclusively, on the leaves, especially the underside.

Each stoma (singular) is surrounded by a pair of special cells, guard cells.

These guard cells can open and close the stomatal pore.

In this way, they can control the rate of gaseous exchange.

Why is this important?

A

This is important, because terrestrial organisms lose water by evaporation

52
Q

Stomata are minute pores that occur mainly, but not exclusively, on the leaves, especially the underside.

Each stoma (singular) is surrounded by a pair of special cells, guard cells.

These guard cells can open and close the stomatal pore.

In this way, they can control the rate of gaseous exchange.

This is important, because terrestrial organisms lose water by evaporation.

Plants have evolved to balance the conflicting needs of gas exchange and control of water loss by closing stomata at times when water loss would be what?

A

Plants have evolved to balance the conflicting needs of:

  1. Gas exchange
  2. Control of water loss

by closing stomata at times when water loss would be excessive

SAJID A Level AQA Biology (69 decks)

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