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Biology > 3) Organisms Exchange Substances With Their Environment > Flashcards

3) Organisms Exchange Substances With Their Environment Flashcards

- Exchange - Mass transport

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1
Q

why do larger organisms require exchange systems?

A

because they have a larger surface area to volume ratio and so cannot rely on simple diffusion

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2
Q

why can single-celled organisms rely only on diffusion for gas exchange?

A

because the diffusion pathway is short

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3
Q

give 3 feature of an efficient gas exchange surface

A
  • large surface area
  • thin
  • good blood supply/ventilation
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4
Q

why is good blood supply/ventilation necessary for efficient gas exchange?

A

to maintain a steep concentration gradient

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5
Q

why can’t gases diffuse through fish’s skin?

A

they have an impermeable membrane that gases can’t diffuse through

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6
Q

describe the gas exchange surface of bony fish

A
  • four pairs of gills, each supported by an arch
  • along each arch, there are gill filaments with further projections on them, lamellae
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7
Q

how does the flow of blood and water across the lamellae aid gas exchange?

A
  • blood and water flow across the lamellae in a counter-current direction (in opposite directions)
  • this maintains a steep concentration gradient so maximum O₂ diffuses into the deoxygenated blood from the water and gas exchange occurs along the whole length of the lamellae
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8
Q

why can fish not survive very long out of water?

A

water flow holds the lamellae apart so out of water they stick together

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9
Q

describe the process of ventilation in fish

A
  • fish opens its mouth and lowers buccal cavity floor, allowing water to flow in
  • fish closes its mouth causing the buccal cavity floor to raise
  • this increases pressure and forces water over the gill filaments by the difference in pressure between the mouth cavity and opercular cavity
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10
Q

what are tracheae?

A

microscopic air-filled tubes for gas exchange in insects

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11
Q

what are spiracles?

A

pores on insects’ surface which air moves through into the tracheae

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12
Q

what are tracheoles?

A

smaller tubes that branch of the tracheae which have thin, permeable walls and go to individual cells

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13
Q

what does the tracheal system allow insects to do in relation to oxygen transport?

A

oxygen diffuses directly into the respiring cells

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14
Q

how is carbon dioxide transported out of insects’ cells?

A

moves down concentration gradient towards spiracles to be released into the atmosphere

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15
Q

how do insects move air in and out of the spiracles?

A

by rhythmic abdominal movements

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16
Q

what is the main gas exchange surface in plants?

A

the surface of the mesophyll cells in the leaf

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17
Q

how do gases move in and out of a leaf?

A

through stomata in the epidermis

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18
Q

how are stomata adapted to control water loss and gas exchange?

A

they can open to allow gas exchange and close to prevent water loss

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19
Q

what controls the opening and closing of stomata?

A

guard cells

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20
Q

what adaptions do insects have to prevent water loss?

A
  • can close spiracles using muscles
  • waterproof waxy cuticle over body and tiny hairs around spiracles to reduce evapouration
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21
Q

what adaptations do plants have to prevent water loss?

A

if the plant becomes dehydrated the guard cells lose water and become flaccid, closing the pore

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22
Q

what are xerophytes?

A

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

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23
Q

give five adaptations of xerophytes to minimise water loss

A
  • stomata sunk in pits
  • layer of hairs on the epidermis
  • curled leaves with stomata inside
  • fewer stomata
  • waxy, waterproof cuticles on leaves and stems
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24
Q

explain how having stomata sunk in pits helps a xerophyte prevent water loss

A

traps moist air so reduces the water potential gradient between leaf and air

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25
Q

explain how having a layer of hairs on the epidermis helps a xerophyte prevent water loss

A

traps moist air around the stomata reducing the water potential gradient between the leaf and air

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26
Q

explain how having curled leaves with the stomata inside helps a xerophyte prevent water loss

A

protects the from wind - windy conditions would increase the rate of diffusion and evporation

27
Q

explain how having fewer stomata helps a xerophyte prevent water loss

A

there are fewer places for water to leave

28
Q

explain how having waxy, waterproof cuticles on leaves and stems helps a xerophyte prevent water loss

A

reduces evaporation

29
Q

why is the volume of oxygen to be absorbed and the volume of carbon dioxide to be removed large in mammals?

A
  • they are relatively large organisms with a large volume of respiring cells
  • they maintain a high body temperature related to their high metabolic and respiratory rates
30
Q

what is the site of gas exchange in mammals?

A

the lungs

31
Q

what is the purpose of the ribcage?

A

to support and protect the lungs

32
Q

what is the trachea?

A

flexible airway, supported by rings of cartilage

33
Q

what are the tracheal walls made up of?

A

muscle lined with ciliated epithelium and goblet cells

34
Q

what are the bronchi?

A

two divisions of the trachea, each leading to one lung

35
Q

what is the role of external and internal intercostal muscles between ribs?

A

contract to raise and lower the ribcage

36
Q

what is the purpose of the diaphragm?

A

separates the lungs from the abdomen

37
Q

where in the lungs does gas exchange take place?

A

in the alveoli

38
Q

how are the trachea and bronchi held open?

A

by c-shaped rings of cartilage on the walls

39
Q

what is the inner lining of the trachea and bronchi composed of?

A

ciliated epithelium and goblet cells

40
Q

what are the walls of the bronchioles made out of?

A

smooth muscle and elastic fibres

41
Q

what adaptations do the bronchi have to prevent dirt particles travelling down?

A

mucus, secreted by goblet cells, traps dirt particles and cilia move the dirt-covered mucus towards the throat

42
Q

what are the bronchioles?

A

series of branching divisions of the bronchi

43
Q

what are the bronchiole walls made of? why?

A
  • muscle
  • allows them to constrict to control air flow in and out of the alveoli
44
Q

what are the alveoli?

A

microscopic air-sacs at the end of bronchioles

45
Q

state and explain three ways alveoli are adapted for gas exchange

A
  • one cell thick (reduces diffusion pathway for gases)
  • constant blood supply by capillaries (maintains steep concentration gradient)
  • millions of alveoli (increases surface area for gas exchange)
46
Q

what is the role of goblet cells?

A

secrete mucus to trap bacteria and dust

47
Q

what is ventilation?

A

the flow of air in and out of the alveoli

48
Q

describe the process of inspiration

A
  • external intercostal muscles contract, internal intercostal muscles relax
  • ribs move upwards
  • diaphragm contracts and flattens
  • volume in thorax increases, lowering the pressure
  • pressure gradient between atm and inside lungs causes air to be forced into the lungs
49
Q

describe the process of expiration

A
  • internal intercostal muscles contract, external intercostal muscles relax
  • ribs lower
  • diaphragm relaxes and moves upwards
  • this decreases volume inside the thorax, increasing pressure
  • pressure gradient between atm and inside lungs forces air out of the lungs
50
Q

what is a spirometer used to measure?

A

lung volume

51
Q

what is vital capacity?

A

the maximum volume of air that can be inhaled or exhaled in a single breath

52
Q

what is tidal volume?

A

the volume of air taken in at each breath when the body is at rest

53
Q

what is breathing rate?

A

the number of breaths per minute

54
Q

how can breathing rate be calculated from a spirometer trace?

A

counting the number of peaks or troughs in a minute

55
Q

what is residual volume?

A

the volume of air that is always present in the lungs

56
Q

what is digestion?

A

the hydrolysis of large biological molecules into smaller molecules which can be absorbed across cell membrane

57
Q

what is the role of the oesophagus?

A

carries food from the mouth to the stomach

58
Q

what is the role of the stomach?

A
  • store and digest food, especially proteins
  • has glands that secrete enzymes that digest proteins
59
Q

what is the role of the ileum?

A
  • further digests food by enzymes, produced by its walls and glands
  • absorbs products of digestion into blood stream
60
Q

how is the ileum adapted for absorption of products of digestion?

A
  • walls folded into villi to increase surface area
  • microvilli further increase surface area
  • villi only one cell thick for short diffusion pathway
  • continual flow of blood through maintains steep concentration gradient
61
Q

what is the role of the large intestine?

A

absorbs water

62
Q

what are the two stages of digestion?

A
  • physical breakdown
  • chemical breakdown
63
Q
A

Biology (8 decks)

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