Gas exchange Flashcards

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1
Q

what do most exchange surfaces have in common

A

large surface area
thin - short diffusion pathway
steep concentration gradient

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2
Q

how do single celled organisms exchange gases

A

through surface

by diffusion

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3
Q

why is there no need for a gas exchange system in single celled organisms

A

they have a relatively large surface area + short diffusion pathway

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4
Q

where is there a higher concentration of oxygen

A

in water than in the fish

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5
Q

where does water enter from

A

the mouth

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6
Q

where does water pass out from

A

the gills

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7
Q

what is each gill made of

A

thin plates

called gill filaments

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8
Q

what do gills provide

A

large surface area

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9
Q

what are gill filaments covered in

A

lamellae

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10
Q

what do lamellae do

A

increase the surface area even more

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11
Q

how do lamellae increase rate of diffusion

A

have lots of blood capillaries

thin surface layer

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12
Q

how do blood and water flow

A

in opposite directions

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13
Q

what is a counter - current system

A

blood and water flowing in opposite directions

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14
Q

what does a counter-current system maintain

A

a concentration gradient

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15
Q

how does the counter-current system maintain a concentration gradient

A

concentration of oxygen in water always higher than in blood
so as much oxygen diffuses into blood from water as possible

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16
Q

what are tracheae

A

air filled pipes

17
Q

what is the function of tracheae

A

gas exchange

18
Q

how does air move into the trachea

A

through pores on surface

called spiracles

19
Q

how does oxygen from the air travel to cells in the insect

A

down the concentration gradient

20
Q

how does the oxygen get to each individual respiring cell

A

trachea branches into tracheoles
which have thin, permeable walls
and branch off into each cell

21
Q

how does carbon dioxide leave the cells?

A

down its concentration gradients

through the spiracles

22
Q

how do insects move air in/out the spiracles

A

through rhythmic abdominal movement

23
Q

what is the main site of exchange in plants

A

mesophyll cells in leaf

24
Q

how are spongy mesophyll cells adapted for exchange

A

large surface area

25
Q

through what do gases move in/out the cells

A

stomata

26
Q

what controls the opening of the stomata

A

guard cells

27
Q

how would guard cells control the opening of the stomata if too much water is lost

A

guard cells become flaccid

closing the opening

28
Q

how can insects reduce water oss

A

close their spiracles using muscles
waterproof waxy cuticle all over body
tiny hairs around spiracles

29
Q

how can plants reduce water loss

A

guard cells become flaccid

which closes the pore

30
Q

what are xerophytes

A

plants adapted for life in warm, dry or windy conditions where water loss is a problem

31
Q

what are some xerophytic adaptations

A

stomata sunk in pits

layer of hairs on epidermis

curled leaves with stomata on inside

reduced number of stomata

waxy, waterproof cuticles on leaves + stem

32
Q

how do sunken stomata reduce water loss

A

trap moist air -
reducing con gradient of water between leaf + air
- reduces amount of water diffusing

33
Q

how do layers of hair on epidermis reduce water loss

A

to trap moist air around stomata

reducing con gradient of water between leaf + stomata reduces amount of water diffusing

34
Q

how do curled leaves reduce water loss

A

protecting stomata from wind

reducing chance of diffusion + evaporation

35
Q

how does a reduced no of stomata reduce water loss

A

fewer places for water to escape

36
Q

how do waxy, waterproof cuticles reduce water loss

A

reduce evaporation