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AQA Biology > 3.1 Adaptations for Gas Exchange > Flashcards

3.1 Adaptations for Gas Exchange Flashcards

1
Q

What happens to the surface area of an organism as it gets bigger?

A

Increases

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2
Q

What happens to the volume of an organism as it gets bigger?

A

Increases

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3
Q

What happens to the surface area:volume of an organism as it gets bigger?

A

Decreases

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4
Q

Why does surface area:volume decrease as an organism gets bigger?

A

Surface area is divided by volume so if the volume gets larger by a bigger factor the ratio will decrease

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5
Q

How can organisms with a large surface area:volume get oxygen and glucose?

A

Diffusion across surface
No specialised exchange surface is needed

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6
Q

Name an organism that relies on getting materials through diffusion across its surface.

A

Single cell organisms e.g. bacteria

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7
Q

Give examples of specialised exchange surfaces.

A

Lungs, gills, tracheoles, small intestine villi

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8
Q

How do organisms exchange materials if they’re bigger than single celled but small enough not to need an exchange system?

A

Body shape adaptations required to increase rate of diffusion

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9
Q

How is a leaf adapted to make diffusion of gases quicker?

A

Flat - large surface area
Thin - short diffusion pathway
Airspaces in spongy mesophyll

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10
Q

What layer of the leaf does carbon dioxide need to reach?

A

Palisade

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11
Q

Where in the leaf is carbon dioxide low in concentration during the day?

A

Palisade cells as they are constantly using it for photosynthesis

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12
Q

Where in the leaf is oxygen high in concentration during the day?

A

Palisade cells as they are constantly producing it in photosynthesis

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13
Q

Which way does oxygen diffuse relevant to leaves?

A

Out of the palisade cells -> the air

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14
Q

Which way does carbon dioxide diffuse relevant to leaves?

A

Into the leaf from the air -> palisade cells

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15
Q

What happens to the rate of photosynthesis at night?

A

Stops

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16
Q

Describe the rate of respiration during the day/night.

A

Constant level as plant always needs to release energy and respiration does not require sunlight

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17
Q

How will the concentration gradient for oxygen in the leaf change at night?

A

Becomes lower in leaves than air as plant is no longer producing oxygen in photosynthesis and using it up in respiration

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18
Q

How will the concentration gradient for carbon dioxide in the leaf change at night?

A

Becomes higher in leaves than air as plant is no longer using carbon dioxide up in photosynthesis but is producing it in respiration

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19
Q

How do plants get gases in/out of the leaves?

A

Through the stomata

20
Q

How are the stomata of a plant controlled?

A

The guard cells open/close them

21
Q

What are xerophytes?

A

Plants that live in low water environments

22
Q

What does a xerophyte need to be adapted for?

A

Reduced water loss

23
Q

How are rolled leaves an adaptation for xerophytes?

A

Less surface area of leaf so less water can evaporate

24
Q

How are less stomata an adaptation for xerophytes?

A

Less water can evaporate out

25
Q

How is a thicker waxy cuticle an adaptation for xerophytes?

A

Reduces water loss

26
Q

How are stomata sunk in pits/grooves an adaptation for xerophytes?

A

Keep water vapour close to stomata to reduce the water potential gradient

27
Q

How are hairs surrounding the stomata an adaptation for xerophytes?

A

Trap water particles close to the stomata to reduce the water potential gradient

28
Q

Describe an experiment to test the hypothesis “xerophytes have less stomata than a common daisy”.

A

Count the stomata on leaf of a daisy and leaf of a xerophyte using a microscope / nail varnish and peel off
Multiple repeats and calculate mean for xerophyte plant and mean for daisy
Keep surface area of leaf / species of xerophyte / field of view the same each time
Use a stats test to see if there is a significant difference

29
Q

Describe an experiment to test the hypothesis “xerophytes have less stomata on their upper surface than a common daisy”.

A

Take leaves from xerophyte and daisy and find the mass
Cover the lower surface in waterproof vaseline to block stomata on the lower surface from losing water
Leave for same time period and reweigh
Compare the mass lost from leaves and should see xerophyte lost less mass
Keep surface area of leaves/species of plant/room temperature the same

30
Q

What are spiracles?

A

Tiny holes in an insects exoskeleton

31
Q

What are tracheoles?

A

Tubes that connect the spiracles and muscle

32
Q

Why is the concentration of oxygen near an insects muscle always low?

A

Insects use muscles to make the abdominal cavity bigger and smaller and push air in/out

33
Q

What is abdominal pumping?

A

The insect uses muscles to make the abdominal cavity bigger and smaller to push air in/out

34
Q

What is the role of abdominal pumping in gas exchange for insects?

A

Increases the concentration gradient by pulling in oxygenated air

35
Q

Why do large, active insects do more abdominal pumping than smaller ones?

A

More respiration to release more energy so more oxygen required

36
Q

How does the fluid at the end of the tracheoles make gas exchange quicker?

A

Increases surface area and shortens diffusion distance

37
Q

What does oxygen do in the fluid at the end of tracheoles?

A

Dissolves

38
Q

Why does the fluid at the end of tracheoles move into insects muscles?

A

Muscles respire anaerobically and produce lactic acid
Reduces the water potential of the muscle so water moves in by osmosis

39
Q

Where do fish absorb oxygen from the water?

A

Gills which are full of blood capillaries

40
Q

What problems do fish have to overcome when extracting oxygen from water?

A

Oxygen at lower concentration in water than air

41
Q

How do gills achieve a large surface area?

A

Many lamallae and filaments

42
Q

How do gills achieve a short diffusion distance?

A

Walls of gill fiaments are one cell thick

43
Q

How do gills achieve a large concentration gradient?

A

Countercurrent flow of water and blood

44
Q

What is the countercurrent mechanism?

A

Water and blood flow in opposite directions
The water always has a higher concentration of oxygen than the blood
Oxygen is able to diffuse into the blood along the entire length of the gill filament as equilibrium is never reached

45
Q

Why are fish able to have external gas exchange structures?

A

Water is denser than air so they can be supported

46
Q

Why are external gills an advantage?

A

More surface area in contact with water
Shorter diffusion distance

AQA Biology (35 decks)

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