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BIOLOGY - EXCHANGE AND TRANSPORT SYSTEMS > GAS EXCHANGE > Flashcards

GAS EXCHANGE Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What adaptations do gas exchange surfaces have

A

1) large surface area

2) thin - for a short diffusion pathway

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2
Q

Where do single celled organisms exchange gases across

A

their body sirfaces

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3
Q

What process do single celled organisms use to absorb and release gases

A

diffusion

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4
Q

Where do single celled organisms diffuse gases in and out of

A

their outer sirface

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5
Q

How are single celled organisms adapted for gas exchange

A

1) large surface area: volume

2) thin

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6
Q

Why do single celled organisms have no need for a gas exchange system

A

oxygen can take part in biochemical reactions as soon as it diffuses into the cell

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7
Q

What is the internal network of tubes called for gas exchange inside an insect

A

tracheae

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8
Q

How are the tracheae supported and why

A

strengthened rings to stop them collapsing

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9
Q

What is the tracheae divided into

A

smaller dead-end tubes called tracheoles

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10
Q

How does air move into the tracheae

A

pores on surface called spiracles

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11
Q

What are tracheoles

A

smaller tubes that go to individual walls

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12
Q

How are tracheoles adapted for gas exchange

A

thin , permeable walls

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13
Q

How do respiratory gases move in and out of tracheal system

A

1) along a diffusion gradient
2) mass transport
3) end of tracheoles are filled with water

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14
Q

Explain respiratory gases move in and out of tracheal system through diffusion gradient

A

cells are respiring so use up oxygen meaning concentration at end of tubes falls and creates a diffusion gradient & diffusion in occurs.
C02 produced by cells during respiration which creates diffusion gradient in opposite direction & diffuses out

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15
Q

Explain respiratory gases move in and out of tracheal system by mass transport

A

contraction of muscles (rhythmic abdominal movements) can squeeze trachea, meaning mass movement occurs in and out

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16
Q

Exlpain respiratory gases move in and out of tracheal system through tracheoles filled with water

A

muscles around tracheoles respire anaerobically so lactate is produced which is soluble, so lowers water potential of muscle cells = water moves into cells. So volume of tracheal decreases and air drawn in

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17
Q

When would tracheoles filled with water occur

A

during times of major activity

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18
Q

How are spiracles opened and closed

A

by a valve`

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19
Q

What are the limitations of the tracheal system

A

relies on diffusion so needs a short diffusion pathway, meaning size of insects is limited

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20
Q

Why have fish deceloped gills

A

1) waterproof body = gas-tight
2) relatively large SA:V
3) lower concentration of O2 in water than air

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21
Q

Where are the gills located

A

within body of the fish, behind head

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22
Q

What are the gills made up of

A

gill filaments

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23
Q

What are at right angles to the gill filaments

A

gill lamellae

24
Q

What do gill lamellae do

A

increase the surface area of the gill

25
Q

What system do fish use for gas exchange

A

counter-current

26
Q

What adaptations do lamellae have to increase rate of diffusion

A

lots of blood capillaries and thin surface layer = short diffusion pathway

27
Q

What is the counter current system

A

blood flows in one direction and blood flows in the opposite

28
Q

How does oxygen get to the gills

A

water containing oxygen enters through fishs mouth and is forced over the gills through openings on each side of its body

29
Q

What does the counter current system ensure

A

that a large concentration gradient is maintained, allowing for maximum diffusion

30
Q

How does the counter current system work (the countercurrent exhchange principal)

A

it means that no equilibrium is reached, as the oxygen concentration in the water is always slightly higher than that in the blood so diffusion always occurs

31
Q

Draw the countercurrent flow graph

A

2 lines going parallel down, one always higher than the other
axis : distance along gill plate / saturation with O2

32
Q

Draw the parallel flow graph

A

2 lines, one going up one going down that meet in the middle to form straight line
axis : distance along gill plate / saturation with O2

33
Q

What is the other flow system to countercurrent

A

parallel flow

34
Q

Which blood flows closest to the lamellae & which direction

A

deoxygenated, down

35
Q

which blood flows in the centre of the gil l& which direction

A

oxygenated, up

36
Q

How is gas exchange in plants similar to that pf insects

A

1) no living cell is far from external air so is near a source of 02/C02
2) diffusion takes place in gas phase (air) so it is more rapid than if it were in water

37
Q

Where does gas exchange for dicotyledonous plants occur

A

surface of mesophyll cells

38
Q

Where does gas exchange occur for most plants

A

in the leaves

39
Q

How are leaves adapted for gas exchange

A

1) many small pores (stomata) and no cell is far from a stomata = short diffusion pathway
2) lots of interconnecting air-spaces that occur throughout mesophyll so gases can readily come in contact with mesophyll cells
3) large SA = rapid diffusion

40
Q

What are the stomata surrounded by

A

guard cells

41
Q

What do guard cells do and what does this mean

A

open and close the stomatal pore, means they can control the rate of gaseous exchange

42
Q

Why do they need guard cells

A

so they can control water loss, through closing them when water loss would be excessive

43
Q

How do guard cells open stomata

A

increase water content so become turgid and open stomatal pore

44
Q

How do guard cells close stomata

A

decrease water contenct so become flacid and close stomatal pore

45
Q

Where are mesphyll cells located

A

between upper and lower epidermis

46
Q

Why do organisms need a method for preserving water

A

gas exchange requirs thin surface, which increases rate of water loss

47
Q

What adaptations do insects have for conserving water loss

A

1) smal SA:V - minimise area water is lost from
2) waterproof, waxy outer skeleton (cuticle) over body
3) spiracles - openings around tracheae at body surface which can be closed, so can control water loss
4) hair around spiracles - reduces evaporation

48
Q

What are the waxy cuticles of insects made of

A

chitin

49
Q

Why can’t plants have a small SA:V

A

they photosynthesise which requires a large SA:V to capture light & exchange gases

50
Q

What adaptations do terrestrial plants have to limit water loss

A

1) guard cells become flacid so close stomatal pore, limiting water loss
2) waterproof covering

51
Q

What are xerophytes

A

plants adapted to living in areas with limited water supply

52
Q

What adaptations do xeropytic plants have to limit water loss

A

1) thick cuticle - shortens pathway
2) curled leaves - stomata inside, protecting them from wind, traps water so increases water potential = minimum conc gradient
3) hairy leaves - trap moist air around stomata, smaller conc gradient
4) stomata in pits - trap moist air increasing conc gradient
5) reduced number of stomata - fewer areas to transpire from

53
Q

What does wind do to the rates of evaporation and diffusion

A

increases it

54
Q

How much water loss can occur via the cuticle

A

10%

55
Q

Give and example of a plant with hairy leaves

A

heather plant

56
Q

Give and example of a plant with sunken stomata

A

pine trees

57
Q

What other plants have similar adaptations to xeropytes

A

plants in sand dunes, salt marshes, cold regiona

BIOLOGY - EXCHANGE AND TRANSPORT SYSTEMS (11 decks)

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