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AQA Biology AS level S > Gas Exchange > Flashcards

Gas Exchange Flashcards

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1
Q

What does gas exchange occur over?

A

A gas exchange surface

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2
Q

What is a gas exchange surface?

A

A boundary between the outside environment and the internal environment of an organism

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3
Q

What do organisms need to diffuse across gas exchange surfaces as quickly as possible?

A

Oxygen

Carbon dioxide

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4
Q

What 2 things do gas exchange surfaces have in common?

A

Large Surface Area

Thin so there is a short diffusion pathway

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5
Q

What does maintaining a steep concentration gradient do?

A

Increase the rate of diffusion?

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6
Q

What 3 things do a single-celled organism have to allow gases to be exchanged?

A

Large Surface Area
Thin surface
Short diffusion pathway

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7
Q

Why do fish have special adaptations for gas exchange?

A

There is a lower concentration of oxygen in water than in air

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8
Q

What is the gas exchange surface in fish?

A

Gills

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9
Q

How do gills work?

A

Water containing oxygen enters through the fishes mouth and passes through the gills `

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10
Q

What are gills made from?

A

Lots of thin plates called gill filaments

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11
Q

What do gill filaments give?

A

A large surface area for gas exchange which increases the rate of diffusion

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12
Q

What are the gill filaments covered in?

A

Lots of tiny structures called lamellae

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13
Q

What does the lamellae on the gill filaments do?

A

Increase the surface area even more

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14
Q

What does the lamellae have lots of?

A

Blood capillaries

Thin surface layer of cells to speed up diffusion between the water and the blood

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15
Q

What is the counter current system in fish?

A

The system in which blood flows in one direction and water flows in the opposite direction across the gills of a fish

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16
Q

In the gills of a fish what 2 things flow through the lamellae?

A

Blood flows through in one direction

Water flows over them in the other

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17
Q

What does the counter current system cause?

A

Water with high oxygen concentration flows next to blood with a lower oxygen concentration

18
Q

What does the counter current system maintain?

A

A steep concentration gradient between the water and the blood

19
Q

What substance do plants need for photosynthesis?

A

Carbon dioxide

20
Q

What waste gas does phtotsynthesis produce?

A

Oxygen

21
Q

What do plants need for respiration?

A

Oxygen

22
Q

What waste gas does respiration produce?

A

Carbon dioxide

23
Q

What is the gas exchange surface in plants?

A

The surface of mesophyll cells in a leaf

24
Q

How are mesophyll cells adapted?

A

They have a large surface area

25
Q

Where are mesophyll cells in a plant?

A

Inside the leaf

26
Q

How do gases move in and out of a leaf?

A

Through pores in the epidermis

27
Q

What are the pores in the epidermis called?

A

Stomata

28
Q

What controls the opening and closing of the stomata?

A

Guard cells

29
Q

What can the stomata do?

A

Open to allow the exchange of gases and close if the plant is losing too much water

30
Q

What do insects have that they use for gas exchange?

A

Tracheae

31
Q

What are tracheae?

A

Microscopic air-filled pipes

32
Q

How does air move into the tracheae?

A

Through pores on the surface called spiracles

33
Q

Where does oxygen travel down in an insect?

A

Down the concentration gradient towards the cells

34
Q

What do the tracheae branch off into?

A

Smaller tracheoles

35
Q

What do tracheoles have?

A

Thin, permeable walls

Go into individual cells

36
Q

Why does the tracheoles in an insect go into individual cells?

A

The oxygen diffuses directly into the respiring cells

It is transported by the blood

37
Q

How is Carbon Dioxide from the cells transported?

A

It moves down its own concentration gradient towards the spiracles to be released into the atmosphere

38
Q

What are spiracles?

A

Pores on the surface

39
Q

What do insects do to move air in and out of the spiracles?

A

Rhythmic abdominal movements

40
Q

What do you tend to lose when exchanging gases?

A

Water

41
Q

What do insects do if they lose too much water?

A

Close their spiracles
Have a waterproof, waxy cuticle over their body
Tiny hairs around their spiracles reducing evoparation

42
Q

During the day, how is the plants stomata usually kept?

A

Open

AQA Biology AS level S (10 decks)

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