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Biology > 2.2 gas exchange > Flashcards

2.2 gas exchange Flashcards

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1
Q

features allowing rapid diffusion of gases

A

large SA
thin
moist
permeable
good blood supply (some)

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2
Q

how does a large SA allow a rapid diffusion of gases

A

relative to the volume of the organism so that diffusion is rapid enough to meet its needs

gases have more area to diffuse

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3
Q

thin
rapid diffusion of gases

A

so that diffusion paths for gases are short

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4
Q

moist
rapid diffusion of gases

A

so that gases can dissolve before diffusion

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5
Q

permeable-
rapid diffusion of gases

A

to allow gases to pass through

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6
Q

what does increasing the size of an organism result in

A

a decreasing surface area to volume ratio

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7
Q

why do gas exchange surfaces need to adapt

A

-to meet the metabolic demands of different organisms
-as the size of an organism size increases

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8
Q

adaptations of amoeba

A

small single-celled organisms that live in aquatic environments
large SA compared to its volume so diffusion across the cell surface membrane can meet the needs of the whole organism (not just one cell)
gas exchange surface is thin resulting in short diffusion paths to the centre of its ‘body’

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9
Q

adaptions of flatworms

A

aquatics animals that have evolved a flattened shape
increasing the SA to volume ratio of the body surface for gas exchange
it also means diffusion paths for respiratory gases are short (no part of the body is far from the surface)

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10
Q

4 things

adaptations of earthworms

A
  1. live in damp soil environments that have evolved an extended tubular shape
    this increases SA to volume ratio
  2. keeps its body surface moist by secreting mucus
  3. more active, higher metabolic rate,
  4. longer diffusion paths than flatworms
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11
Q

what does it mean that earthworms are more active than flatworms

A

they have a higher metabolic rate, their tubular shape gives them a lower surface area to volume ratio than the flatworm and could result in a larger diffusion paths

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12
Q

examples of larger multicellular organisms

A

fish, amphibians, reptiles, birds, mammals and insects

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13
Q

what do the larger multicellular organisms have that are different

A

high oxygen requirements
smaller surface area to volume ratio

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14
Q

why do the larger organisms have high oxygen requirements

A

increased metabolic rate, they’re warm blooded, more active

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15
Q

why do the larger organisms have smaller surface area to volume ratio

A

usually much lager organisms

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16
Q

what do these larger organisms have that make gas exchange more efficient

A

a specialised gas exchange surface (gills/alveoli)
ventilation system
circulatory system
respiratory pigment

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17
Q

why does having a ventilation system make gas exchange more efficient

A

to maintain diffusion gradients by moving air or water over the exchange surface

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18
Q

why does having a circulatory system make gas exchange more efficient

A

to maintain diffusion gradients by transporting gases between respiring cells and the exchange surface

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19
Q

why does having a respiratory pigment make gas exchange more efficient

A

(haemoglobin) in the blood to increase its oxygen-carrying capacity

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20
Q

what do insects have in terms of gas exchange

A

small surface area to volume ratio, cannot use their body surface to exchange gases by diffusion
covered in hard, impermeable exoskeleton made of chitin sometimes with an additional waxy layer to reduce water loss

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21
Q

where does exchange if gases occur in insects

A

through pores called spiracles, running along the side of the body. gases then travel through the tracheal system- a branching system of chitin-lines tubes called tracheae

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22
Q

name of the ends if the tracheae

A

tracheoles
site of gas exchange
every cell in the body will be close to the end of the tracheal

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23
Q

what gases go where

A

oxygen enters, carbon dioxide leaves via the trachioles

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24
Q

gas exchange in less active insects

A

gases move along the tubes of the tracheal system by diffusion

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25
Q

gas exchange in more active insets

A

so rhythmical movement of the abdomen help to pump the air in and out of the abdomen and ventilate the tracheal system. this is a natural consequence of high energy activity like flight.

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26
Q

site of gas exchange in reptiles

A

occurs in the lungs
they’re sac like and have more complex folding than amphibians
ventilation is aided by the movement of the ribs by the intercostal muscles

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27
Q

site of gas exchange in birds

A

blood capillary network

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28
Q

site of gas exchange in amphibians (frogs) when inactive

A

moist skin and mouth lining are the main sites of gas exchange. (on land or in water)
if its inactive the frogs oxygen demands are low and can easily be met by these regions
frog stays in damps areas so their skin stays moist. skin is moist and permeable with an extensive capillary network below it

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29
Q

site of gas exchange when active (amphibians)

A

two internal sac-like lungs are the site of gas exchange. when its active these organs provide the extra surface area needed to obtain extra oxygen

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30
Q

how are amphibian lungs ventilated

A

by movements of the mouth and nostril. no ribcages

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31
Q

what do lungs in frogs have

A

all the features allowing a rapid diffusion of gases

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32
Q

site of gas exchange in tadpoles

A

starts with gills (external)
become internal before the lose them and develop a pair of lungs

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33
Q

different types of fish
example

A

cartilaginous (marine only, made of cartilage) e.g shark
bony fish (made of bone, scales and have gills covered by operculum) e.g every other fish

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34
Q

structure of gills

A

4 rows of bony, gill arches on each side of the fishes head
gill filaments, gill arch, gill-rakers

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35
Q

function of gill-rakers

A

used to filter food (plankton) out of the water passing over them and often help protect the delicate filaments from damage.

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36
Q

site of gas exchange in fish

A

thin gill filaments

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37
Q

what are the gill filaments covered by
what does this do

A

covered by smaller gill lamellae, these increase the surface area of the exchange surface

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38
Q

blood flow in the gills

A

flows through the gill arches, out into the filaments and then out again into the gill lamellae before making the return journey to the gill arch

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39
Q

water flow in the gills

A

flows over the gill lamellae as it passes through the gills and this is where gas exchange takes place

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40
Q

adaptations of fish gills for gas exchange

A

large SA
thin
good blood supply
permeable
NOT MOIST

41
Q

how does the fish gills have a large SA

A

theres a large number of gill filaments and gill lamellae

42
Q

how are the gills adapted to be thin

A

gill lamellae are very thin, short diffusion paths for gases to reach the capillaries

43
Q

how are the gills adapted to have a good blood supply

A

have an extensive capillary network, maintains a diffusion gradient (for respiratory gases) between the water and the blood

44
Q

how are the gills adapted to be permeable

A

have haenoglobin in the blood for carriage of oxygen

45
Q

why are the gills not adapted to be moist

A

they are naturally moist as they live in water

46
Q

explain the ventilation mechanism in bony fish (including volume and presuure)

A

mouth opens, opperculum closes buccal cavity floor lowers (volume increases, low pressure)
water flows in (from a region of high pressure (outside mouth) to low (mouth) pressure
mouth closes floor of buccal cavity rises (v decreases, p increases) water (high pressure) is forced over gills, oppercullum opens, water leaves

47
Q

2 directions of blood flow

A

parallel
counter-current

48
Q

explain parallel flow

A

blood flows in the same direction as the water passing over the gills

49
Q

explain countercurrent flow

A

blood flows in the opposite direction to the water passing over the gills

50
Q

which direction of flow is better for the fish

A

counter-current to maximise the amount of oxygen that can be extracted from water

51
Q

role of the trachea

A

transpots air to the bronchi

52
Q

role of the bronchi

A

transports air to the bronchioles

53
Q

job of the bronchioles

A

transports air to the alveoli

54
Q

what are the alveoli

A

respiratory surface and the site of gas exchange

55
Q

what is the pleural cavity

A

filled with pleural fluid which is made by the membranes

56
Q

job of the pleural fluid

A

acts as a lubricant so that the ribcage can move more easily past the lungs as we breathe

57
Q

what are organisms that have gas exchange surfaces outside their body in danger of

A

dehydration and excessive water loss

58
Q

benefit of having an internal gas exchange surface

A

reduces water loss

59
Q

what is the wall of the alveoli made up of

A

squarmous epithelium

60
Q

adaptations of alveoli for gas exchange

A

large SA
thin
moist
permeable
good blood supply

61
Q

how are alveoli adapted to have a large SA

A

lots of small alveoli

62
Q

how are alveoli adapted to be thin

A

alveolar walls/ capillary walls are thin, they’re one cell thick. this provides a short diffusion pathway distance for oxygen to enter the blood and carbon dioxide to leave the blood

63
Q

how are alveoli adapted to be moist

A

contain surfactant, allows gases to dissolve, more efficient diffusion of gases

64
Q

how are alveoli adapted to be permeable

A

they have a shared cell surface membrane between the capillary and the alveoli, this allows for the diffusion of gases

65
Q

how are alveoli adapted to have a good blood supply

A

they provide a good blood supply/ capillary network. this maintains a steep concentration gradient for oxygen and CO2.

66
Q

what is lung surfactant

A

a mixture of proteins and phospholipids that line the moist alveolar membranes
reduces pressure, to expand alveoli during inhalation
reduces surface tension and prevents them sticking together and collapsing during exhalation

67
Q

explain what happens during inhalation

A

intercostal muscles push ribs out by contracting. ribcage moves up and out. diaphragm contracts down and flattens
volume of thoracic cavity increases
pressure in thoracic cavity decreases below atmospheric pressure
resulting the direction of air back into the lungs

68
Q

explain what happens during expiration

A

intercostal muscles relax and push ribs back in, ribcage relaxes down and in. diaphragm relaxes moves up dome shape. volume of thoracic cavity decreases. pressure in thoratic cavity increases above atmospheric pressure
resulting direction of air out of the lungs

69
Q

how does negative pressure breathing work

A

for air to enter the lungs, the pressure inside the lungs must be below atmospheric pressure

70
Q

job of cilia

A

moves/sweeps the mucus away from the lungs

71
Q

job of mucus

A

traps dust particles, made in goblet cells

72
Q

job of goblet cells

A

mucus is made

73
Q

where is mucus made

A

goblet cells

74
Q

why is the basement membrane important

A

it is the layer that the cells sit on

75
Q

type of blood vessels in lung

A

capillaries

76
Q

type of muscle in the trachea

A

smooth muscle
it is involuntary

77
Q

what adaptations do leaves have

A

large surface area
thin
lots of chlorophyll
good transport

78
Q

why is it important leaves have a large surface area

A

so they can absorb light for photosynthesis (make glucose)

79
Q

why is it important that leaves are thin

A

short diffusion paths

80
Q

why is it important leaves have lots of chlorophyll

A

to absorb light

81
Q

site of gas exchange for a plant

A

leaf

82
Q

structure of a stomata

A

lower epidermis cells
2 guard cells

83
Q

role of the guard cells

A

open and close the stomata, when the stomata is open, guard cells are smaller

84
Q

role of the stomata

A

allow the exchange of gases between the atmosphere and the internal tissue of the leaf
they also control water loss by evaporation from the leaf (transpiration)

85
Q

describe the process of stomata opening

A

1- potassium ions are actively transported from the epidermal cells into the guard cells. requires ATP
2- the extra potassium ions and makati create a lower water potential in the guard cells
3- water moves into the guard cells by osmosis
4- the guard cells expand (become turgid)
5- guard cells curve away from each other
6- stoma pores open

86
Q

why do the guard cells turn away from each other

A

because the inner wall of each guard cell is thicker and inelastic

87
Q

how do stomata cells close

A

1- potassium ions transported out of the guard cells
2- water potential of the cell rises and water leaves
3- guard cells become flaccid as they lose water
4- cells straighten up
5- stoma pores close

88
Q

how would cyanide effect the opening/closing of the stomata

A

cyanide is a respiratory inhibitor, it inhibits production of ATP. potassium ions won’t be able to actively transport into the cell

89
Q

why do the stomata close

A

reduce water loss

90
Q

role of the waxy cuticle

A

reduces water loss from upper epidermis

91
Q

role of upper epidermis

A

transparent cells lacking chloroplasts to maximise photosynthesis

92
Q

role of palisade mesophyll cells

A

engaged, densely arranged and contain many chloroplasts

93
Q

role of air spaces in song mesophyll

A

allow efficient gas exchange

94
Q

role of the stomata

A

allow gases in and out of the lead (allow loss of water vapour to ensure a continuous flow up the stem to the leaves)

95
Q

role of the xylem vessels

A

provide water for photosynthesis

96
Q

role of the phloem

A

transport sucrose made in photosynthesis away from the leaf

97
Q

role of the guard cells

A

control gas exchange and water loss by opening/closing the stomata

98
Q

adaptations of the leaf for gas exchange

A

-spongy mesophyll tissue allows for the circulation of gases
-plant tissues are permeated by air spaces
-stomatal pores allow gas to enter and leave the leaf
-gases diffuse through the stomata down a concentration gradient. gases then diffuse through the intercellular spaces between mesophyll cells

Biology (12 decks)

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