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WJEC AS Biology > Adaptations for Gas Exchange- Unit 2.2 > Flashcards

Adaptations for Gas Exchange- Unit 2.2 Flashcards

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1
Q

What do gill rakers do?

A

Remove debris

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2
Q

Describe what is meant by diffusion.

A

The net movement of molecules from a higher concentration to a lower concentration. It occurs passively. (without energy)

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3
Q

What is the capillary endothelium?

A

The single layer of cells of the capillary wall.

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4
Q

Why do multicellular organisms need a specialised gas exchange mechanism?

A

They have a lower surface area to volume ratio so cells are further away from the surface, meaning diffusion has to occur over a greater distance.

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5
Q

Why does the amoeba have adequate gas exchange?

A
  • Large surface area to volume ratio
  • Thin so short diffusion pathway
  • Small
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6
Q

How does a continuous supply of oxygen reach all tissues of an earthworm?

A
  • Large surface area
  • Skin is the respiratory surface which is moist
  • Tubular structure
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7
Q

What does the cartilage do in the lungs?

A

Keeps the trachea open as it’s made from rings of strong, bendy cartilage.

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8
Q

What do goblet cells do?

A

Produce mucus to trap inhaled dust.

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9
Q

What are cilia and what do they do?

A

Hairs on cells in the trachea, bronchi and bronchioles. They move to push mucus with trapped particles upwards. (away from lungs)

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10
Q

What do elastic fibres do and where are they located?

A

Between the alveoli. They stretch lungs when inhaling, recoil when exhaling to push air out.

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11
Q

What is and where is the pleural membrane?

A

Protective lining on the lungs.

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12
Q

What is the alveolar epithelium?

A

The single layer of cells lining the alveoli.

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13
Q

Describe the path that oxygen take across the alveoli.

A
  • oxygen diffuses out of alveoli
  • across alveolar epithelium
  • across capillary endothelium
  • then into haemoglobin in blood
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14
Q

Describe the path of carbon dioxide across alveoli.

A
  • Diffuses into alveoli from blood
  • Then breathed out through lungs
  • To trachea
  • Then out of mouth and nose
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15
Q

What liquid does alveoli secrete?

A

Surfactant

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16
Q

What is an alveoli?

A

A microscopic air sac.

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17
Q

What does surfactant of the alveoli do?

A

Stops alveoli collapsing by lowering surface tension of water layer lining alveoli.

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18
Q

Name four adaptations the alveoli have to speed up the rate of diffusion.

A
  • Thin exchange surfaces (alveolar epithelium)
  • Short diffusion pathways (alveolar epithelium one cell thick)
  • Large surface area to volume ratio
  • Steep concentration gradient (between alveoli and capillaries)
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19
Q

How does oxygen enter and travel though fish?

A

•Oxygenated water enters gills in one-way current that continually flows by pumping mechanisms.

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20
Q

What are lamellae?

A

Thin plates in the gills that create a large surface area. They have lots of capillaries and a thin surface layer.

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21
Q

What is counter-current flow?

A

Blood flowing over the lamellae in one direction with water flowing over in the opposite direction.

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22
Q

Why is a counter-current flow beneficial?

A

A concentration gradient is maintained between water and blood. (as much oxygen as possible diffuses from water into blood)

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23
Q

What is metabolic rate?

A

The rate of energy expenditure by the body.

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24
Q

What are gill filaments?

A

Specialised respiratory area. Water is forced over them by a ventilating mechanism.

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25
Q

How is ventilation in a bony fish achieved?

A

Pressure changes in the buccal and opercular cavities.

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26
Q

What is the buccal in a fish?

A

The mouth.

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27
Q

What are the opercular cavities in a fish?

A

The gills.

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28
Q

Describe stage 1 of the ventilation mechanism of a bony fish. (4)

A
  • Mouth opens & floor of buccal cavity lowers
  • Volume of buccal cavity increases & pressure decreases
  • Operculum remains closed
  • Water pulled into buccal cavity from outside due to pressure change
29
Q

Describe stage 2 of the ventilation mechanism in a bony fish. (3)

A
  • Mouth closes
  • Buccal cavity contracts, raising floor of cavity
  • Water forced across gills
30
Q

Describe stage 3 of the ventilation mechanism of a bony fish. (2)

A
  • Pressure in gill cavity increases & forces operculum open

* Water leaves via operculum

31
Q

What is the operculum?

A

The gill slit.

32
Q

Fish have haemoglobin and a circulatory system to do what?

A

Carry oxygen throughout the fish.

33
Q

How do insects reduce water loss?

A

Have evolved a rigid waterproof exoskeleton covered by a cuticle.

34
Q

How does gas exchange occur in insects?

A

Through paired holes (spiracles) which lead into a system of branched, chitin lined air tubes (tracheae)

35
Q

What are the ends of the tracheae called in an insect?

A

Tracheoles

36
Q

Name 4 labels on an insect.

A
  • Head
  • Thorax
  • Spiracle
  • Abdomen
37
Q

What ventilates the tracheal system in an insect?

A

Compression and expansion of the abdomen.

38
Q

When the abdomen expands in an insect, the thorax spiracles are… and the abdominal spiracles are…

A

Open

Closed

39
Q

As the abdomen is compressed in an insect, the thorax spiracles… and the abdominal spiracles…

A

Close

Open

40
Q

Does oxygen enter or exit the thorax spiracles in an insect?

A

Enter

41
Q

Does oxygen enter or exit the abdominal spiracles in an insect?

A

Exit

42
Q

What is a thorax in a human?

A

An airtight compartment.

43
Q

Order the path that oxygen takes from entering the body to the site of gas exchange in a human.

A

1• Trachea
2• Bronchi
3• Bronchioles
4• Alveoli

44
Q

Describe inspiration.

A
  • Intercostal muscles contract, raising ribcage upwards and outwards.
  • Diaphragm contracts and flattens.
  • Volume of thorax increases and pressure decreases.
  • Air enters and lungs expand.
45
Q

Describe expiration.

A
  • Intercostal muscles relax, moving ribcage inward and downward.
  • Diaphragm relaxes and curves upwards.
  • Volume of thorax decreases and pressure increases.
  • Air forced out of lungs.
46
Q

Why are surfactants often given to premature babies?

A

It prevents the alveoli of their immature lungs from sticking together.

47
Q

Why do plants need to exchange gases?

A

For respiration and photosynthesis.

48
Q

What is the main gas exchange surface on a plant?

A

Leaf.

49
Q

How is a leaf adapted for gas exchange?

A
  • Thin
  • Flat
  • Large surface area
  • Short diffusion pathway
50
Q

Order each part of a flowering plants leaf from top to bottom.

A 
1• Waxy cuticle 
2• Upper epidermis
3• Palisade mesophyll
4• Spongy mesophyll
5• Vascular bundle
6• Guard cell
7• Stomata
51
Q

Name the function of the waxy cuticle in a leaf.

A

Reduces water loss from leaf surface by evaporation.

52
Q

Name function of upper epidermis in a leaf. What are they?

A

Transparent cells which allow light to pass through mesophyll tissue. They synthesise and secrete the waxy cuticle.

53
Q

What does the palisade mesophyll do in a leaf? What do they contain?

A

Contain many chloroplasts for photosynthesis. This layer is the main photosynthetic tissue.

54
Q

What do the spongy mesophyll and air spaces do in a leaf?

A

Spongy palisade cells photosynthesise. Air spaces between cells allow for circulation of gases.

55
Q

Two examples of vascular bundles:

A

Xylem and phloem.

56
Q

What do the vascular bundles do in a plant?

A

Xylem- water and mineral transport.

Phloem- transport of products of photosynthesis. (sucrose and amino acids)

57
Q

Function of guard cells in a leaf:

A

They become turgid and flaccid due to changes in water potential. This opens and closes stomata pore.

58
Q

What does the stomata do in a plant?

A

Allows gas exchange.

59
Q

Why can chloroplasts rotate and move in mesophyll cells in a leaf?

A

To allow arrangement of the best possible position for light absorption.

60
Q

How many guards cells bound a pore/stoma in a leaf?

A

2

61
Q

Describe the structure of a guard cell in a leaf. (4)

A
  • Have chloroplasts.
  • Thick inner wall and thin outer wall.
  • Thick inner wall causes cell to become curved when swelled, opening the stomatal pore.
  • Can change shape to open/close stomata, helping control gas exchange and water loss.
62
Q

Why are stomata found on the lower leaf surface?

A

To reduce water loss from evaporation. (sun hits top of leaf so being at the top would result in leaf becoming flaccid)

63
Q

Do most stomata close or open at night?

A

Close

64
Q

During the day when light intensity is sufficient, the stomata is…

A

Open

65
Q

How does water enter/exit the guard cells in a leaf?

A

Osmosis

66
Q

When the stomata closes, water potential…

A

Increases

67
Q

When the stomata opens, water potential…

A

Decreases

68
Q

What is parallel flow in a fish?

A

Blood and water flow in the same direction.

WJEC AS Biology (9 decks)

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