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AQA AS Biology > Gas Exchange > Flashcards

Gas Exchange Flashcards

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1
Q

What is the ideal surface area to volume ratio?

A

Large

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2
Q

What is the surface area to volume ratio of large organisms?

A

Small

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3
Q

How do single celled organisms exchange gas and why?

A
  • Direct oxygen diffusion- They have a very high SA:V- They absorb oxygen across their membrane
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4
Q

How do flat worms exchange gas and why?

A
  • Direct oxygen diffusion- Flat so they have a short diffusion pathway to all cells- High SA:V
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5
Q

How do small mammals exchange gas and why?

A
  • Highly specialised organ systems- Higher SA:V than big mammals- Lose more heat per gram- Faster rate of respiration- More oxygen needed - Need to maintain a concentration gradient
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6
Q

How do large mammals exchange gas and why?

A
  • Highly specialised organ systems- Lower SA:V than small mammals- Lose less heat per gram- Slower rate of respiration- Less oxygen needed
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7
Q

What does the efficiency of gas exchange depend on?

A
  • Small diffusion pathway
  • High concentration gradient
  • High surface area
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8
Q

What is the structure of an insects gas exchange system?

A
  • Waxy cuticle- Spiracles- Trachea lined with cells
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9
Q

How do insects exchange gas?

A
  • Air enters through the spiracles- Oxygen diffuses down a concentration gradient along the trachea- Oxygen diffuses out of trachea and into cells- Ventilation maintains the concentration gradient
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10
Q

How do insects prevent water loss?

A
  • Open and close spiracles (prevent evaporation)- Covered in a waxy cuticle
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11
Q

How do the stomata help prevent water loss?

A

When cells have a lot of water they are turgid and when cells don’t they are flaccid. Flaccid guard cells close the stomata

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12
Q

How do dicotyledonous plants carry out gas exchange?

A
  • Takes place in the spongey mesophyll (large SA)- Gaseous diffusion in and out of the mesophyll- Stomata is the gap between 2 guard cells- Stomata can open/close to increase/decrease water loss
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13
Q

How do xenophytic plants prevent water loss?

A
  • Curled leaf, sunken stomata and epidermis hairs allow water vapour to build up, decreasing the water vapour gradient- Waxy cuticle and fever stomata reduce evaporation
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14
Q

Where does photosynthesis take place?

A

Palisade cells

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15
Q

What is the structure of the gas exchange site in a fish?

A
  • Gill filaments- Lamellae- Counter current flow
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16
Q

How do fish exchange gas?

A

-Gill filaments (lamellae) have a large surface area which increases the efficiency of diffusion.-Thin epithelial cells line the filaments (short diffusion pathway)-Countercurrent flow maintains a high concentration gradient -Circulation of blood and the ventilation of water maintain the concentration gradient so that low oxygen blood is always next to high oxygen water

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17
Q

What is the structure of the human gas exchange system?

A
  • Trachea branch into bronchi which further branch into bronchioles inside the lungs which have alveoli at the bottom. - Lungs are surrounded by ribs with intercostal muscles between them.- Diaphragm sits bellow the lungs- Alveoli are surrounded by capillaries
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18
Q

How do the lungs increase surface are?

A

Many airsacs called alveoli are found at the end of bronchioles, they have a highly folded membrane with a high surface area

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19
Q

How do the lungs maintain the concentration gradient?

A
  • Ventilation brings in highly oxygenated air and removes unoxygenated air. - Circulation brings in unoxygenated blood (Pulmonary artery) and removes oxygenated blood- Maintaining the high concentration gradient
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20
Q

How do the lungs maintain a small diffusion pathway?

A
  • Alveoli and capillaries have a thin epithelial lining- Gives a short diffusion pathway
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21
Q

What is tidal volume?

A

The volume of air breathed in or out per breath

22
Q

What is ventilation rate?

A

Breaths per minute

23
Q

What is pulmonary ventilation?

A

Total volume of air breathed in per minute

24
Q

How is pulmonary ventilation calculated?

A

Tidal volume x breathing rate

25
Q

What effect does exercise have on tidal volume?

A

It increases because breaths are deeper

26
Q

What effect does exercise have on ventilation rate?

A

It increases because breaths are quicker

27
Q

What effect does exercise have on pulmonary ventilation?

A

It is increased

28
Q

What effect does exercise have on oxygen consumption?

A

It is increased

29
Q

What is oxygen consumption?

A

Volume of oxygen used per minute

30
Q

What is inspiration?

A

Breathing in

31
Q

What is expiration?

A

Breathing oout

32
Q

How does inspiration happen?

A
  • Diaphragm contracts and flattens- External intercostal muscles contract- Ribcage moves up and out- Pressure decreases - Thorax volume increases - Air rushes in from high to low pressure
33
Q

How does expiration happen?

A
  • Diaphragm relaxes and domes- External intercostal musclesrelax- Ribcage moves down and in- Pressure increases - Thorax volume decreases - Air rushes out from high to low pressure
34
Q

What is forced expiration?

A

Internal intercostal muscles contractRibcage is pulled down faster and more frequently

35
Q

What are the internal and external intercostal muscles?

A

An antagonistic pair

36
Q

How is an animal’s ability to lose heat affected by having large ears?

A
  • Greater SA:V- Loses more heat per gram
37
Q

What is a by-product released from respiration?

A

Heat

38
Q

What system within the body carries the waste around?

A

Circulatory

39
Q

What are reasons for diffusion being slow in multicellular organisms?

A
  • Large diffusion pathway to cells deep inside the body- Very thick out membranes compared to single celled organisms- Smaller surface area to volume ratio
40
Q

What adaptation do elephants have in order to to lose heat more quickly?

A

Large, thin ears

41
Q

How do single celled organisms get rid of their waste?

A

They diffuse across their membrane

42
Q

How are gas exchange surfaces adapted for efficient gas exchange?

A
  • Short diffusion pathway- High concentration gradient- High surface area
43
Q

Gases diffuse into leaves via which structure?

A

Stomata

44
Q

What organ do insects use for gas exchange?

A

Trachea

45
Q

What surrounds alveoli?

A

Capillaries

46
Q

Within a leaf, what is it’s main exchange surface called?

A

Mesophyll layer

47
Q

How does air enter the insects?

A

Spiracles

48
Q

In photosynthesis in plants, what gas is needed?

A

Carbon dioxide

49
Q

The diaphragm is made from which type of tissue?

A

Muscle

50
Q

There are muscles which are in between each rib. What are these called?

A

Intercostal

51
Q

What are the ways that insects control water loss?

A
  • Waxy outer cuticle- They can close their spiracles- Water is trapped around the spiracles by hairs

AQA AS Biology (18 decks)

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