3.1 Flashcards

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1
Q

what is gas exchange?

A

the diffusion of O2/CO2 across an exchange surface

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2
Q

how are exchange surfaces adapted?

A

a large surface area, thin, good blood supply, ventilated, moist

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3
Q

what is the quantitative connection between surface area and volume?

A

as side length doubles, sa:vol halves

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4
Q

what is the gas exchange surface for fish?

A

gills

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5
Q

why do fish need a specialised gas exchange surface?

A

small sa:vol, high metabolic rate, high demand for O2, can’t be met by diffusion across body surface

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6
Q

how do gills have a large surface area?

A

lots of gill filaments and each filament has lots of gill lamellae

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7
Q

how do gills have short diffusion distance?

A

gill filaments/ lamellae are squamous epithelial

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8
Q

how do gills have a good blood supply?

A

lots of capillaries

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9
Q

how do gills have a method to maintains concentration gradients?

A

counter current flow

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10
Q

what is counter current flow?

A

water moving across the gills and blood in the capillaries of the gills are moving in opposite directions

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11
Q

what does counter current flow mean?

A

concentration gradient for O2 is maintained across the whole gill lamellae

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12
Q

what happens in the fish when they take in water?

A

1- the mouth opens
2- the operculum closes
3- the floor of the mouth is lowered
4- the volume inside the mouth cavity increases and pressure decreases
5- water flows in as the external pressure is higher than the pressure inside

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13
Q

what happens when a fish to force water out over the gills?

A

1- the mouth closes
2- the operculum opens
3- the floor of mouth is raised
4- the volume inside mouth decreases and the pressure increases
5- water flows out over the gills because the pressure in the mouth is higher than in the opercular cavity and outside

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14
Q

what adaptations do amoebas have?

A

their gas exchange surface is plasma membrane, large sa:vol so has a short diffusion pathway

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15
Q

what adaptations do flatworms have?

A

flat so increase in sa:vol, gas exchange over body surface due to short diffusion pathways

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16
Q

what adaptations are in earthworms?

A

elongated so has an increase in sa:vol, has exchange over body surface, body surface is moist (secrete mucus)

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17
Q

what adaptations do amphibians have?

A

live in moist habitats, water for fertilisation, tadpoles live in water and have gills, transition to land living in metamorphosis, inactive adults use moist skin as respiratory surface, active (mating) adults use lungs

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18
Q

what adaptations do reptiles have?

A

pairs of ribs project from vertebrae, provide support + protection and involved in ventilation, have in-growth of tissues to increase surface area

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19
Q

what adaptations do birds have?

A

system of air sacs, when breathing in any remaining air from previous ventilation is sucked into sacs, ribs cause ventilation, during flight flight muscles ventilate, very efficient with basically no residual gas

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20
Q

what is the structure of the trachea?

A

c shaped cartilage, ciliated epithelium with glands

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21
Q

what is the gas exchange surface in humans?

A

alveoli

22
Q

why is the gas exchange surface internal?

A

helps to keep it moist, protection from damage

23
Q

why does the trachea contain cartilage?

A

to support the trachea and keep it open during pressure changes during ventilation

24
Q

why is the cartilage c shaped?

A

flexible to accommodate changes in shape during ventilation or when food is swallowed

25
Q

what is the epiglottis?

A

flap of tissue that covers the trachea when eating

26
Q

what is the roles of cilia and mucus in defence against disease?

A

mucus traps pathogens and cilia wafts it away from lungs towards the back of the throat

27
Q

what is the pleural cavity for?

A

reduces friction between the lungs and ribs during ventilation

28
Q

what adaptations do alveoli have for short diffusion pathways?

A

alveolus walls are 1 layer of squamous epithelium, capillary wall is 1 layer of endothelium

29
Q

what is the alveoli’s adaptations for large surface area?

A

many very small alveoli

30
Q

what is the alveoli’s adaptations for being moist?

A

coasted in surfactant which reduces surface tension and prevents collapse of alveoli during breathing

31
Q

what are the alveoli’s adaptations for a good blood supply?

A

lots of capillaries which maintains concentration gradient

32
Q

what happens during inspiration in humans?

A

1- external intercostal muscles contract
2- ribs are pulled up and out
3- diaphragm muscles contracts so it flattens
4- outer pleural membrane pulls out and so does inner membrane leading to lungs expanding which increases volume and decreases pressure
5- pressure it higher outside than inside so air is forced into lungs

33
Q

what happens during expiration in humans?

A

1- external intercostal muscles relax
2- ribs move down and in
3- diaphragm relaxed and moves upwards
4- pleural membranes move down and in with ribs so lungs volume decreases and pressure increases
5- air pressure in lungs is higher so air is forced out of the lungs

34
Q

what adaptations do insects have for large surface area?

A

many fine tracheoles

35
Q

what are the adaptations for insects for short diffusion pathways?

A

end of tracheoles are squamous epithelium so are one cell thick

36
Q

what adaptations do insects have for being moist?

A

fluid filled at the end of tracheoles so O2 can dissolve

37
Q

what are insects adaptations for ventilation?

A

body movements force air out of GE system through spiracles

38
Q

what happens during times of high metabolic rate in insects?

A

lactic acid type waste is in body cell, water potential is lower so water moves into the cell by osmosis from tracheole, pulls air down into tracheole

39
Q

what adaptations do insects have to reduce water loss?

A

exoskeleton is made of chitin, spiracles can open and close, around spiracles are hairs that trap water

40
Q

what is the structure of dicotyledon leafs?

A

waxy cuticle, upper epidermis, palisade mesophyll, spongy mesophyll, vascular bundle (bundle sheath parenchyma, xylem, phloem) lower epidermis, stomata and guard cells

41
Q

why is it beneficial that leaves are thin?

A

short diffusion pathways, light penetrates through leaf

42
Q

why is it beneficial that leaves have a large surface area?

A

room for many stomata, capture as much light as possible

43
Q

why is it beneficial that cuticle and epidermis are transparent?

A

light penetrates to the mesophyll

44
Q

why is beneficial that palisade cells are elongated?

A

can accommodate a large number

45
Q

why is it beneficial that palisade are packed with chloroplast?

A

capture as much light as possible

46
Q

why is it beneficial that chloroplasts move and rotate?

A

move into best position for max light absorption

47
Q

why is it beneficial that there is air spaces in spongy mesophyll?

A

allow O2 and CO2 to diffuse between stomata and cells, allow CO2 to diffuse to photosynthesising cells

48
Q

how do stomata open?

A

form between 2 guard cells, inner cell walls are thick and inelastic and outer is thin and elastic, guard cells
expand unevenly

49
Q

what is the mechanism of stamatal opening?

A

malate hypothesis

50
Q

what happens as said in malate hypothesis?

A

1- photosynthesis occurs in chloroplasts to make atp
2- atp is used in active transport to move K+ ions into cell
3- K+ ions cause starch to convert into malate (insoluble to soluble)
4- causes water potential to decrease
5- water moves into cell by osmosis down water potential gradient