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(OCR A) - A-level Biology > 3.1.1 Exchange surfaces > Flashcards

3.1.1 Exchange surfaces Flashcards

1
Q

Method of gas exchange in single called organisms?

A

Simple diffusion

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2
Q

Why do single celled organisms not need specialised exchange surfaces?

A
  • Short diffusion distance due to high SA:V ratio
  • Low metabolic activity
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3
Q

Why do multi celled organisms need specialised exchange surfaces?

A
  • Long diffusion distance due to low SA:V ratio
  • High metabolic activity
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4
Q

How is increased SA a feature of efficient gas exchange?

A

Overcomes limitations of low SA:V ratio

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5
Q

How are thin layers a feature of efficient gas exchange?

A

Allows for shorter diffusion distances

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6
Q

How is a good blood supply a feature of efficient gas exchange?

A

Maintains steep concentration gradient so faster diffusion

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7
Q

How is ventilation a feature of efficient gas exchange?

A

For gases it maintains a steep concentration gradient so faster diffusion

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8
Q

Pathway of air in mammalian gas exchange system?

A

Nasal cavity -> trachea -> bronchus -> bronchioles -> alveoli

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9
Q

Why does the nasal cavity have a good blood supply and moist surfaces?

A

To warm incoming air and create a humid environment (reduced water loss)

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10
Q

Why are the trachea rings incomplete?

A

To allow it to bend when food travels down the oesophagus

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11
Q

What is the trachea supported by?

A

Incomplete rings of cartilage

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12
Q

What is the trachea lined with?

A

Ciliated epithelial and goblet cells

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13
Q

What component is similar in structure to the trachea, but is smaller?

A

Bronchus

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14
Q

What is the structure of bronchioles?

A

No cartilage rings, have smooth muscle and elastic fibres instead

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15
Q

Diameter of alveoli?

A

200-300 µm

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16
Q

What are alveoli made up of?

A

Thin layer of flattened epithelial cells, collagen and elastic fibres

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17
Q

Function of elastic fibres in alveoli?

A

Can stretch when air is drawn in and then return to original size (elastic recoil)

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18
Q

Adaptations of alveoli?

A
  • Large SA
  • Thin walls
  • Good blood supply
  • Good ventilation
  • Liquid surfactant
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19
Q

Function of liquid surfactant on alveoli?

A

Prevent water loss

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20
Q

There is a _______ concentration of oxygen in the alveoli
There is a _______ concentration of oxygen in the blood

A

High
Low

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21
Q

Inspiration is an _________ process

A

Active

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22
Q

Exhalation is a _________ process

A

Passive

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23
Q

INHALATION

External intercostal muscles __________

A

Contract

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24
Q

INHALATION

Rib cage moves ____ and _____

A

Up and out (expands)

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25
Q

INHALATION

Diaphragm __________ and __________

A

Contracts (moves down)
Flattens

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26
Q

INHALATION

Volume of thorax __________

A

Increases

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27
Q

INHALATION

Pressure inside thorax _________ until slightly _______ than atmospheric pressure

A

Decrease
Lower

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28
Q

What is the mechanism of inhalation during exercising?

A

Same mechanism as without exercise

29
Q

EXHALATION

External intercostal muscles _______

30
Q

EXHALATION

Rib cage moves ____ and _____

A

Down and in

31
Q

EXHALATION

Diaphragm __________ and becomes __________

A

Relaxes (moves up)
Dome shaped

32
Q

EXHALATION

Volume of thorax __________

33
Q

EXHALATION

Pressure inside thorax _________

34
Q

FORCED EXHALATION (exercising)

________ intercostal muscles ________

A

Internal
Contract

35
Q

FORCED EXHALATION (exercising)

Ribcage pulled _______ and ______

36
Q

What do the abdominal muscles do during forced exhalation?

A

Contract to push organs upwards against the diaphragm, increasing the internal pressure

37
Q

What happens in asthma?

A
  • Epithelial cells become inflamed
  • Goblet cells secret excess mucus
  • Smooth muscle in bronchioles contract
  • Airways narrowed
38
Q

What is tidal volume?

A

Volume of air that moves into and out of the lungs with each resting breath

39
Q

What is vital capacity?

A

Maximum volume of air that can be breathed in or out in one breath

40
Q

What is inspiratory reserve volume?

A

Maximum volume of air you can breathe in above a normal inhalation

41
Q

What is expiratory reserve volume?

A

Extra amount of air you can force out above the normal tidal volume of air you breathe out

42
Q

What is residual volume?

A

Volume of air left in lungs when you have exhaled as hard as possible

43
Q

What is total lung capacity?

A

Sum of the vital capacity and residual volume

44
Q

What is breathing rate?

A

Number of breaths (in and out) taken in one minute

45
Q

How to calculate ventilation rate?

A

Tidal volume x breathing rate (per min)

46
Q

What happens to tidal volume during exercise?

47
Q

What is the normal breathing rate?

A

12-18 breaths per minute

48
Q

What does a spirometer show?

A
  • Vital capacity
  • Tidal volume
  • Breathing rate
49
Q

What does each curve on a spirometer represent?

A

Breathing rate

50
Q

What does the vertical size of each curve on a spirometer represent?

A

Tidal volume

51
Q

How does gas exchange occur in insects?

A

Tracheal system

52
Q

What is a spiracle?

A

Opening in the exoskeleton which has valves and allows air to enter

53
Q

What are the valves in a spiracle called?

A

Sphincters

54
Q

Why does a spiracle need valves?

A
  • To control the opening and closing of it
  • Closed most of the time to prevent water loss
55
Q

Structure of trachea in insects?

A

Lined by spirals of chitin which provide support

56
Q

Function of tracheoles in insects?

A

Site of gas exchange

57
Q

Function of tracheal fluid?

A
  • Provides barrier that prevents oxygen from moving
  • When insect is moving then fluid is stopped to create more space for gas exchange
58
Q

Mechanism of ventilation in insects?

A
  • Air sacs inflating and deflating
  • Abdominal muscles creating pumping movement
59
Q

Gas exchange system in fish?

60
Q

Why do fish gills have stacks of filaments that overlap?

A

To slow movement of water so there us more time for gas exchange

61
Q

Why do the filaments on fish gills have rows of lamellae?

A

To increase SA

62
Q

What do lamellae contain?

A

A rich blood supply of capillaries

63
Q

What is a counter current system?

A

Blood flow is in the opposite direction to water flow with a constant gradient between them

64
Q

Why is the counter current system needed?

A

To ensure concentration gradient is maintained

65
Q

In fish gills the water with ________ oxygen concentration is found adjacent to the __________ blood

A

Lowest
Deoxygenated

66
Q

INHALATION IN FISH

  • Fish _______ mouth
  • Buccal cavity floor ________
  • Volume ________
  • Pressure _______
  • Pressure is higher outside of mouth so water flows in
A
  • Open
  • Lowers
  • Increases
  • Decreases
67
Q

EXHALATION IN FISH

  • Fish _____ mouth
  • Buccal cavity floor ______
  • Pressure ________ in buccal cavity
  • Water flows from buccal cavity to _________ (high to low pressure)
  • Pressure increases in ________
  • _________ forced open and water exists
A
  • Closes
  • Rises
  • Increases
  • Gill cavity (x2)
  • Operculum
68
Q

What is operculum?

A

Flap of tissue covering gills

(OCR A) - A-level Biology (26 decks)

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