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A level Biology > Unit 2.2 - Adaptations for Gas exchange > Flashcards

Unit 2.2 - Adaptations for Gas exchange Flashcards

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1
Q

What are gases always exchanged by?

A

Diffusion

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2
Q

What do organisms exchange gas with?

A

The environment

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3
Q

What are some gases that organisms exchange with the environment?

A

O2 and CO2

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4
Q

When is O2 involved in gas exchange?

A

For aerobic respiration
Produced by plants

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5
Q

When is CO2 involved in gas exchange?

A

Waste product of aerobic respiration
Used by plants that photosynthesise

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6
Q

Give an example of a single celled organism

A

Amoeba

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7
Q

Is gas exchange across the cell surface membrane sufficient for amoeba? Why?

A

Yes, as it has a large surface area to volume ratio

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8
Q

Which method of gas exchange is the only one required for amoeba?

A

Gas exchange across the cell surface membrane

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9
Q

What type of organisms cannot rely on diffusion alone?

A

Larger, multicellular organisms

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10
Q

What can larger, multicellular organisms not rely on alone?

A

Diffusion

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11
Q

Why can larger, multicellular organs not rely on diffusion alone for gas exchange?

A

Smaller surface area to volume ratio

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12
Q

What must larger, multicellular organisms have for gas exchange as they cannot rely on diffusion alone?

A

A ventilation mechanism
(Sometimes) a circulatory system with specialised blood pigments

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13
Q

What do specialised blood pigments do?

A

Ensure that respiratory gases are exchanged with the body tissue rapidly

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14
Q

Draw and label an amoeba

A

(See notes)

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15
Q

Where does aerobic respiration occur in an amoeba?

A

Inside the cell

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16
Q

Describe how respiration occurs in an amoeba

A

Oxygen concentration is low inside so it moves from an area of high to low concentration down a concentration gradient
Also, it’s non-polar, so it easily passes through the membrane

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17
Q

What is oxygen that allows it to easily pass through a membrane?

A

Non-polar

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18
Q

Fick’s law

A

Rate of diffusion = surface area x difference in concentration
————————————————————
Length of diffusion pathway

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19
Q

Diffusion pathway

A

Distance from cell centre to the middle of the cell wall

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20
Q

What has to increase in Fick’s Law equation for the rate of diffusion to increase?

A

Surface area or difference in concentration

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21
Q

What had to increase under Fick’s Law for the rate of diffusion to decrease?

A

Length of diffusion pathway

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22
Q

If an organism is larger in size, what happens to its surface area to volume ratio?

A

It decreases

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23
Q

What type of organism has a smaller surface area to volume ratio?

A

Larger organism

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24
Q

Why does an increased size in an organism mean that the surface area to volume ratio decreases and what does this mean for the time taken for gas to diffuse into the organism?

A

As the organism gets bigger, the surface area increases, but the volume increases more
It’s the surface area that gases diffuse through after all
And…
The length of the diffusion pathway is larger
So, it takes longer for gas to diffuse into the organism

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25
Q

Is it a large or small surface area to volume ratio that provides efficient diffusion?

A

Large

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26
Q

What diffuses in and out of a flatworm?

A

O2 in, CO2 out (nothing different lol)

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27
Q

How does the flatworm achieve the best rate of diffusion?

A

Short diffusion pathway
Increased surface area (long, thin, flat body)
Exchanges gases over its whole body

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28
Q

Why does the earthworm have a more complicated gas exchange system?

A

It’s a larger organism

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29
Q

Why is relying on diffusion alone not sufficient in the case of the earthworm?

A

The distance from the cell wall to centre is too great to rely on diffusion alone to provide oxygen to internal organs

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30
Q

Why does oxygen diffuse into organisms anyway?

A

To provide oxygen for internal organs

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31
Q

What do earthworms have due to the fact that they cannot rely on diffusion alone for gas exchange?

A

A circulatory system that carries oxygen from the outer surface to the internal body

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32
Q

What does the circulatory system in an earthworm do?

A

Carries oxygen from the outer surface to the internal body

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33
Q

Sketch and label the circulatory system in an earthworm

A

(See notes)

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34
Q

What does oxygen do in terms of diffusion n an earthworm and why?

A

Higher 02 concentration int the air, so 02 diffuses into the blood

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35
Q

Where does oxygen diffuse to and from in an earthworm?

A

From the air into the blood

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36
Q

Why is there a short diffusion pathway in the circulatory system of an earthworm?

A

The blood vessels are very close to the body surface

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37
Q

What does the fact that blood vessels are very close to the body surface mean for earthworms?

A

Short diffusion pathway

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38
Q

What does the blood of earthworms contain?

A

Haemoglobin

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39
Q

What is haemoglobin in the blood of earthworms?

A

A protein that binds to oxygen

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40
Q

What’s the name given to haemoglobin in an earthworms blood?

A

A respiratory pigment

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41
Q

Sketch and label the cell structure in an earthworm

A

(See notes)

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42
Q

What are earthworms covered in and why?

A

Mucus, as oxygen first needs to dissolve on the surface of the worm before diffusing into the blood

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43
Q

What allows oxygen to dissolve on the surface of the worm before diffusing into the blood?

A

Mucus

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44
Q

List the 5 properties of gas exchange surfaces

A

Large surface area
Thin
Permeable to gases
Moist
Concentration difference

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45
Q

Why is having large surface are beneficial for gas exchange surfaces?

A

Ensures diffusion is sufficient to provide for the organisms needs

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46
Q

Why is being thin beneficial for gas exchange surfaces?

A

To provide a short diffusion pathway

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47
Q

Why is being permeable to gases vital for gas exchange surfaces?

A

To allow respiratory gases to pass through

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48
Q

Why is being moist vital for gas exchange surfaces?

A

Gases must dissolve before they can diffuse across membranes

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49
Q

Why is having a concentration difference vital for gas exchange surfaces?

A

To ensure sufficient diffusion of O2 in and CO2 out

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50
Q

Which property of a gas exchange surface ensures that diffusion is sufficient to provide for an organisms needs?

A

Large surface area

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51
Q

Which property of a gas exchange system is vital to provide a short diffusion pathway?

A

Being thin

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52
Q

Which property of a gas exchange system is vital in allowing respiratory gases to pass through?

A

Permeability to gases

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53
Q

Which property of a gas exchange system is important for ensuring that gases dissolve before they diffuse across membranes?

A

Moist

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54
Q

Which property of gas exchange systems ensure sufficient diffusion of O2 in and CO2 out?

A

Concentration difference

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55
Q

What’s the gas exchange surface of mammals?

A

Alveoli

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56
Q

What’s the alveoli to mammals?

A

The gas exchange surface

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57
Q

Draw and label the lungs

A

(See notes)

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58
Q

Which process can we use to model lungs and how does this work?

A

Plastimation
Plastic compound injected into the dead organism and it fills the airways and solidifies

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59
Q

What are bronchioles?

A

Thin airways that lead to the alveoli

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60
Q

Thin airways that lead to the alveoli

A

Bronchioles

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61
Q

What kind of tissue do the bronchioles have and why is this useful?

A

Ciliated epithilum
Cilia move mucus from the lungs towards the mouth - carries any small particles out from the lung in the mucus to avoid disease

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62
Q

What do the network of capillaries on an alveoli contain and why?

A

Blood with low levels of oxygen for oxygen to diffuse from the alveoli to the blood

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63
Q

What type of tissue do the alveoli’s cells have and why is this useful?

A

Squamous epithilum
Broad, flat and thin in cross-section
= short diffusion pathway between alveoli and capillaries in the blood

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64
Q

Where are the red blood cells situated in the capillaries? Why is this useful?

A

Right along the edges = short diffusion pathway between alveoli and red blood cells

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65
Q

What are the properties of the alveoli which enable them to function as gas exchange surfaces in mammals?

A

Thin
Large surface area
Moist
Concentration difference
Permeable to gases

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66
Q

Why are alveoli thin and what does this lead to?

A

Shape of squamous epithilum (+ capillary walls are 1 cell thick) = short diffusion pathway

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67
Q

Why do alveoli have a large surface area and what does this lead to?

A

Millions of alveoli + large capillary network surrounding each alveolus = sufficient diffusion

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68
Q

Why are alveoli moist and what does this lead to?

A

Lungs are internal = prevents water loss + tissue fluid lining allows gases to dissolve and diffuse across

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69
Q

Why do alveoli have a concentration difference and what does this lead to?

A

Capillary network = low oxygen blood reaches the alveoli so that there’s a concentration gradient for it to diffuse form the alveoli to the blood + ventilation ensures the O2 concentration of the alveolus is high

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70
Q

Why are alveoli permeable to gases?

A

To allow respiratory gases to pass through

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71
Q

Where does oxygen diffuse to and from in terms of the alveoli and blood?

A

From the alveoli to the blood

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72
Q

What are the advantages of internal gas exchange systems?

A

Reduces heat loss to enviornment
Reduces water loss to environment
Protected from physical damage
Protection from infections

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73
Q

Give an example of an internal gas exchange system?

A

The lungs

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74
Q

What is a surfactant?

A

An anti-sticking chemical

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75
Q

Where is a surfactant to be found?

A

Covering the surface of each alveolus

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76
Q

Whats the name for the anti-sticking chemical covering the surface of each alveolus?

A

Surfactant

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77
Q

Is surfactant a mucus? Why?

A

No, mucus is much thicker

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78
Q

What’s the purpose of surfactant and how does it do this?

A

Prevents the alveoli collapsing when breathing out - reduces surface tension
Also, it allows gases to dissolve before they move in or out

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79
Q

What do surfactants contain?

A

Phospholipids and proteins

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80
Q

What are babies lungs filled with and what’s the solution to this when they’re born?

A

Liquid (they got their oxygen through the umbilical cord)
Surfactant slows the lungs to open out, allowing the lungs to fill with air

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81
Q

What’s often given to premature babies and why?

A

Due to them being born before the production of the surfactant, they’re often given it, as without it, the alveoli in their immature lungs would stick together

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82
Q

How is the trachea a kept from collapsing?

A

C-shaped cartilage

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83
Q

What does the “c-shape cartilage” do?

A

Stops the trachea from collapsing

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84
Q

Why IS the c-shape cartilage that stops the trachea from collapsing c-shaped?

A

It’s not a complete ring and doesn’t meet at the back as this allows the oesophagus behind it to bulge as a bonus of food is swallowed, without meeting a hard structure, which would prevent food from moving past

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85
Q

Ventilation

A

Breathing
Brings gases to or from a gas exchange surface

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86
Q

Does ventilation occur in all organisms?

A

Only some

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87
Q

What does the ventilation of the lungs occur via?

A

Negative pressure ventilation

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88
Q

What do we have 2 sets of in the lungs and what are they?

A

2 sets of intercostal muscles
Internal and external

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89
Q

What do the internal and external intercostal muscles in the lungs form together?

A

Antagonistic pairs

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90
Q

Name antagonistic pairs in the lungs and explain what this means

A

Internal and external intercostal muscles in the lungs
Work against each other - relax when the other contracts

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91
Q

Thoracic cavity

A

Place where the lungs sit

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92
Q

Place where the lungs sit

A

Thoracic cavity

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93
Q

Draw and label the structures of a lung required to explain inspiration and expiration

A

(See notes)

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94
Q

What type of process is breathing in and why?

A

Active process (muscle contraction requires energy)

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95
Q

Fancy WJEC words for inhalation and exhalation

A

Inspiration
Expiration

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96
Q

Describe the steps of inspiraiton

A
  1. The external intercostal muscles contract
  2. The ribs are pulled upwards and outwards
  3. At the same time, the diaphragm muscles contract, so the diaphragm flattens
  4. The outer pleural membrane is attached to the thoracic cavity wall so it is pulled up and out with the ribs, and the lower part is pulled down with the diaphragm
  5. Inner membrane follows = increase in the volume of the thoracic covalent as the lungs expand
  6. Increases the volume of the alveoli
  7. Reduces air pressure in the lungs
  8. Atmospheric air pressure is now greater than the pressure in the lungs, so air is forces into the lungs as it moves from the atmosphere to the lungs down a pressure gradient
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97
Q

Why is it called “negative pressure ventilation”?

A

As during inspiration, the air pressure in the lungs becomes lower than the atmospheric air pressure

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98
Q

Pulmonary

A

Relating to the lungs

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99
Q

Word for relating to the lungs

A

Pulmonary

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100
Q

What type of process is breathing out?

A

Mainly passive

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101
Q

Describe the steps of expiration

A
  1. The external intercostal muscles relax
  2. The rubs move downwards and inwards
  3. At the same time, the diaphragm muscles relax, causing the diaphragm to dome upwards
  4. The pleural membranes move down and in with the ribs, and the lower parts move up with the diaphragm
  5. The elastic properties of the lungs allow their volume to decrease, decreasing the volume of the volume inside the alveoli + lung volume decreases
  6. Increases the pressure in the lungs
  7. Air pressure of the lungs is now greater than atmospheric pressure, so air is forces out of the lungs, down a pressure gradient
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102
Q

What property of the lungs allows their volume to decrease?

A

The elastic properties of the lungs

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103
Q

What’s attached to the thoracic cavity wal?

A

The outer plural membrane

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104
Q

Which muscles contract upon inspiraiton?

A

The external intercostal muscles contract

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105
Q

What happens to the diaphragm upon inspiration?

A

The muscles contract and it flattens

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106
Q

In which direction are the ribs pulled during inspiration?

A

Upwards and outwards

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107
Q

Which intercostal muscles relax during experiation?

A

External intercostal

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108
Q

What do the external intercostal muscles do during expiration?

A

Relax

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109
Q

What do the ribs do during expiration?

A

Move downwards and inwards

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110
Q

What does the diaphragm do during expiration?

A

Diaphragm muscles relax and it domes upwards

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111
Q

What’s the importance of ventilation in the lungs?

A

it’s needed to maintain a concentration gradient between the air in the alveoli and the blood

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112
Q

What can cilia NOT sweep out of the lungs and why?

A

Bacteria - they’re far too small

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113
Q

What are the lungs surrounded by?

A

2 membranes - pleural membranes

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114
Q

Pleural membranes

A

Membranes that surround the lungs

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115
Q

What are the 2 types of pleural membrane?

A

Outer an inner

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116
Q

What’s the outer pleural membrane attached to?

A

The chest wall

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117
Q

What’s the inner pleural membrane attached to?

A

Covers the lungs

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118
Q

What’s between the pleural membranes?

A

Pleural filled space (pleural cavity)

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119
Q

What does pleural cavity do?

A

Creates a surface tension so that the outer and inner pleural membranes reman in contact

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120
Q

What do the outer and inner pleural membranes do with each other?

A

Slide over each other to enable the movements of the rib cage and diaphragm

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121
Q

What could cause the lungs to collapse?

A

If a bacterial infection or infection occurs to the pleural membrane

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122
Q

Why would a bacterial infection cause the lungs to collapse?

A

Bacteria would create a gas in the pleural cavity

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123
Q

What type of injury could cause the lungs to collapse?

A

Puncture of the membrane could displace the liquid of the pleural membrane

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124
Q

If a bacterial infection or injury occurs to the pleural membrane, what can happen?

A

The lungs can collapse

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125
Q

What cannot occur if the lungs have collapsed?

A

Negative pressure won’t be able to be created in order to respire

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126
Q

Give examples of some types of amphibians

A

Frogs, toads, newts, salamanders

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127
Q

What usually happens to amphibians eggs once they hatch? Give an example

A

They hatch into their aquatic form (e.g - tadpoles) and then go through metamorphosis to reach different stages (e.g - frog)

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128
Q

What type of animals go through metamorphosis from their aquatic form when hatched?

A

Amphibians

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129
Q

What’s different about the axolotl compared to other amphibians?

A

It doesn’t go through metamorphosis from its large form - it just keeps getting bigger in this larva form and remains in the water

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130
Q

What’s the gas exchange surface of the axolotl and what occurs here?

A

Their gills - they get oxygen dissolved from the water and give out CO2

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131
Q

Which amphibian is different to the others in that it remains in its aquatic form permanently?

A

Axolotl

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132
Q

How do most adult amphibians exchange gases?

A

Most have lungs, that are simple and primitive
However, they can also exchange gases directly through their thin, permeable skin

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133
Q

Does a tadpole have lungs?

A

No, it has gills for gas exchange

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134
Q

How come amphibians can exchange gases through their skin?

A

It’s thin and permeable

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135
Q

Describe the lungs of an amphibian

A

Simple and primitive

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136
Q

What can amphibians do in water?

A

Can exchange gas through the outer body surface for a long time

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137
Q

When do amphibians use their lungs? Give some examples

A

During periods of increased activity
Swimming, jumping or mating

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138
Q

What is used by amphibians during periods of increased activity?

A

Lungs

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139
Q

What’s the name for the respiration that uses lungs?

A

Pulmonary respiration

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140
Q

What’s the name for the respiration that uses the skin to respire?

A

Cutaneous respiration

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141
Q

Why do most amphibians live in moist places?

A

They use their skin to respire - needs to be kept moist for gas exchange

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142
Q

Are amphibians cold or warm blooded?

A

Cold blooded

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143
Q

What does the fact that amphibians are cold blooded mean for them?

A

They don’t use much energy to keep warm and don’t require as much O2 as mammals

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144
Q

Are mammals warm or cold blooded?

A

Warm

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145
Q

What does the fact that mammals are warm blooded mean for them?

A

They use metabolic processes (e.g - respiration) to keep warm, using O2 and generating internal heat)

146
Q

Cutaneous respiration

A

Using the skin to respire

147
Q

Pulmonary respiration

A

Using the lungs to respire

148
Q

Name the characteristics of the respiratory surface for amphibians, reptiles and birds

A

Large surface area
Moist surface
Internal lungs
Ventilation mechanism
Thin walls
Circulatory system with blood pigments

149
Q

What does the fact that amphibians, reptiles and birds have a large surface area mean for them?

A

Rapid diffusion of respiratory gases

150
Q

How do amphibians regulate their body temperature (as they’re cold blooded and so don’t use metabolic processes)?

A

Use the environment (e.g - go in the sun, go in the shade)

151
Q

What does the fact that amphibians, reptiles and birds have a moist surface mean for them?

A

Facilitates rapid diffusion of gases

152
Q

What do the fact that reptiles and birds have internal lungs mean for them?

A

Minimised loss of water and heat

153
Q

Which of the following don’t it necessarily apply to all that they have lungs?
amphibians, reptiles and birds

A

Amphibians

154
Q

What does the fact that amphibians, reptiles and birds have respiratory surfaces with thin walls mean for them?

A

Short diffusion pathway

155
Q

Why do amphibians, reptiles and birds have circulatory systems with blood pigments?

A

To carry oxygen (e.g - haemoglobin)

156
Q

Why is a ventilation mechanism important in amphibians, reptiles and birds?

A

Forces the respiratory medium (air) to and from the respiratory surface
O2 is brought to and CO2 is removed from the gas exchange surface

157
Q

What does an inactive amphibian use for gas exchange?

A

Its moist skin

158
Q

What does an active amphibian use for gas exchange?

A

Simple lungs

159
Q

What are the lungs of an amphibian pretty much?

A

A simple pair of hollow sacs

160
Q

Describe the surface area of an amphibians lungs

A

Highly folded to give them an increased surface area, but still relatively small compared with human lungs

161
Q

What does an amphibian in the tadpole sage use for gas exchange?

A

Gills

162
Q

Describe the skin of a reptile

A

Impermeable to gases, and so cannot be used as a respiratory surface

163
Q

Compare the lungs of reptiles to those of amphibians

A

More efficient, and so gas exchange occurs exclusively here

164
Q

Where does gas exchange occur exclusively in reptiles?

A

In the lungs

165
Q

How are the lungs of reptiles more efficient than those of amphibians?

A

More complex folding
Ventilation is aided by the movement of the ribs by the intercostal muscles

166
Q

What is ventilation aided by in the lungs of a reptile?

A

The movement of the ribs by the intercostal muscles

167
Q

What can the lungs of a reptile be described to be?

A

Sac like

168
Q

Do reptiles’ lungs have diaphragms?

A

No

169
Q

Do reptiles’ lungs have ribs?

A

Yes

170
Q

Are birds warm or cold blooded?

A

Warm blooded

171
Q

Why is efficient gas exchange essential in birds?

A

They have a high respiration rate

172
Q

Describe the lungs of a bird

A

Small and compact

173
Q

What are bird lungs composed of?

A

Numerous branching air tubes called bronchi

174
Q

Bronchi

A

Branching air tubes of birds

175
Q

Parabronchi

A

Smaller air tubes of the bronchi in the birds lungs, with an extensive blood capillary network

176
Q

Smaller air tubes of the bronchi in a birds lungs

A

Parabronchi

177
Q

What do Parabronchi in birds lungs have?

A

An extensive blood capillary network

178
Q

Where does gaseous exchange take place in a birds lungs?

A

The blood capillary network of the Parabronchi

179
Q

What do Parabronchi end in?

A

Thin walled air sacs which help in ventilation (act like bellows to push air out of them)

180
Q

What is the ventilation of the bird lung bought about by?

A

The movement of the ribs

181
Q

Why is gas exchange effective in bird lungs?

A

Air passes the gas exchange surface twice (during inhalation and expiration)

182
Q

Why is it advantageous that air passes the gas exchange surface twice in the lungs of a bird (during inspiration and expiration)?

A

Provided effective gas exchange

183
Q

What does air pass twice during inspiraiton and expiration in bird lungs?

A

The gas exchange surface

184
Q

What happens to birds during flight in terms of ventilation?

A

The action of the wing muscles ventilate the lungs

185
Q

Draw and label the process of gas exchange in insects

A

(See notes)

186
Q

What do the trachea in insects have?

A

Rings of chitin

187
Q

Which part of the gas exchange system in insects has chitin and which part doesn’t?

A

Chitin - trachea
No chitin - trachioles

188
Q

What do the trachioles do in the gas exchange system in insects?

A

Branch onto tissues and muscles

189
Q

Do insects have lungs?

A

No

190
Q

What else do infects not have in terms of gas exchange apart from lungs?

A

A circulatory system to transport O2 around the body

191
Q

What’s the only type of circulatory system that insects have?

A

Ones for nutrients

192
Q

What do insects have for gas exchange instead of lungs?

A

A system of branching tubes throughout the body

193
Q

What feature do insects have that would TECHNICALLY make their bodies effective for gas exchange?

A

Large surface area to volume ratio

194
Q

Draw and label an insect (in terms of gas exchange)

A

(See notes)

195
Q

Why can’t insects use their bodies for gas exchange?

A

The chain exoskeleton is impermeable to water and gases

196
Q

How many spiracles are on each segment on an insect?

A

2

197
Q

How do insects get air into their spiracles?

A

Pump their abdomens in and out to get air into the spiracles

198
Q

What do the spiracles of an insect come in?

A

Pairs

199
Q

Where d an insect’s spiracles lead to?

A

Trachea

200
Q

What happens to the trachea of insects?

A

Divides into branching trachioles

201
Q

Do trachioles have a lining of chitin? (insects)

A

No, only the trachea

202
Q

Where do the trachioles of insects end?

A

In close contact with muscle cells

203
Q

Where does gas exchange actually occur in insects?

A

In the gap between the trachioles and muscle cells

204
Q

What limits the size of an insect and why?

A

Its gas exchange system, as if it grew much bigger, there would be too much tubing and the system would be too heavy to fly

205
Q

How does the gas exchange system of insects actually work?

A

Ends if trachioles are filled with fluid
The end enters the tissue
The ends of the trachioles are also devoid of cuticle - the respiratory surface is very thin, so O2 diffusion into cells is easy
As respiration occurs in the cell, the products of respiration accumulate in the cell and force the fluid in the trachioles to enter the tissue
The exit of fluid creates low pressure in the tubes and draws in more O2 to the tissues where it’s reacted

206
Q

What happens to an insect when it’s active in terms of gas exchange?

A

Surface area for gas exchange increases

207
Q

Give some examples of bony fish

A

Cod, salmon, trout

208
Q

What type of animals are bony fish and what does this mean for them?

A

Aquatic
Exchange gases with the enviornment

209
Q

Gas exchange surface in fish - what’s good about these?

A

Gills - highly adapted for gas exchange in water

210
Q

What are fish gills covered by?

A

The operculum
(Flap of tissue)

211
Q

Why is it important to have an effective gas exchange system in water?

A

Denser medium than air - much harder to move water in and out of narrow tubes
Low O2 levels compared to air

212
Q

What’s the other type of fish (not bony)?

A

Cartilaginous

213
Q

Examples of cartilaginous fish

A

Sharks
Catfish

214
Q

What works differently between bony and cartilaginous fish?

A

Their gills

215
Q

Draw and label a fish gill

A

(See notes)

216
Q

What’s the gas exchange surface of the gill?

A

Gill filaments

217
Q

Gill rakers purpose

A

Capture food so that they don’t clog up the gills

218
Q

Gall arch purpose

A

Supports the gill

219
Q

What are gill filaments?

A

A specialised respiratory area

220
Q

How are gills adapted for gas exchange?

A

Large surface area - 100s of gill filaments on each gill
Gill filaments are thin

221
Q

What must be done to water in a bony fish and why?

A

Is a denser medium with relatively low O2 content]
Must be forced over the gill filmaments

222
Q

What prevents a fish gill from collapsing?

A

Density of water

223
Q

Why is it important that a fish gill doesn’t collapse?

A

To maintain a large surface area

224
Q

How is water forced over a fish’s gills?

A

By a ventilating mechanism

225
Q

Describe the flow of water over a fish gill

A

One way - unidirectional

226
Q

Draw and label the inside of a fish’s head to help explain negative pressure ventilation

A

(See notes)

227
Q

What’s the name of the type of ventilation that occurs in bony fish?

A

Negative pressure ventilation (like humans)

228
Q

What does an opercular flap do?

A

Can open and close to allow water to flow our behind the head of the fish

229
Q

Describe the steps of negative pressure ventilation taken when a fish opens its mouth

A

Operculum closed
Lowers the floor of the buccal cavity
This increases the volume inside the cavity
This decreases the pressure inside the cavity
Water flows in from high to low pressure

230
Q

Describe the step of negative pressure ventilation taken when a fish closes its mouth

A

Operculum opens
The floor of the buccal cavity is raised
This decreases the volume inside the cavity
This increases the pressure inside the cavity
Water is forced over the gills into the opercular cavity
Water pressure forces the operculum to open
Water exits through the operculum

231
Q

Draw and label a diagram to show counter-current flow in a bony fish

A

(See notes)

232
Q

Which part of the gill is well adapted for gas exchange?

A

Gill lamellae

233
Q

Adaptations of gill lamellae for gas exchange

A

Thin to create a short diffusion pathway
Increase the surface area of the gill filament even more
Excellent blood supply (why fish gills always look pink)
Always moist

234
Q

Which is most effective for gas exchange…
Counter-current flow or parallel flow?

A

Counter-current flow

235
Q

What occurs during counter-current flow?

A

Water and blood flow in opposite directions across the gill plate
Water always has a higher oxygen concentration than the blood, sp oxygen diffuses into the blood down a concentration gradient, across the entire gill plate?

236
Q

Where is oxygen diffused into the blood from the water during counter-current flow?

A

Across the entire gill plate

237
Q

Compare the flow of water between counter-current and parallel flow

A

Water flows across the filament (though the gill plates) in both
C.C - opposite direction to blood flow in the gill capillaries
P - same direction as blood flow in the gill capillaries

238
Q

Compare the concentration gradients between counter-current and parallel flow

A

C.C - a steep oxygen concentration gradient is maintained, allowing diffusion of oxygen across the entire gill plate
P- oxygen concentration gradient is not maintained - equilibrium is reached between the water and the blood, so diffusion ends halfway across the gill filament

239
Q

Compare the diffusion of oxygen from the water to the blood between counter-current and parallel flow

A

C.C - across the entire gill plate
P - doesn’t occur across the entire gill plate

240
Q

Compare the rate of diffusion between counter-current and parallel flow

A

C.C - high
P - lower and decreases as equilibrium is reached

241
Q

Compare the amount of oxygen absorbed into the blood between counter-current and parallel flow

A

C.C - a greater amount
P. - less oxygen (not slower)

242
Q

Is oxygen adsorbed into the blood slower during parallel flow?

A

No, just less of it

243
Q

Compare the % oxygen saturation of the blood between counter-current and parallel flow

A

C.C - higher
P - lower

244
Q

Which flow system is less efficient?

A

Parallel

245
Q

Draw and label a diagram to represent counter-current flow

A

(See notes)

246
Q

Why is there constant diffusion with counter-current flow?

A

Always a concentration difference between water and blood

247
Q

Sketch a graph to represent counter-current flow

A

(See notes)

248
Q

Sketch a graph to represent parallel flow

A

(See notes)

249
Q

What are the 2 mechanisms by which bony fish maintain a concentration gradient of their gas exchange surface?

A

Counter-current flow
Negative pressure ventilation

250
Q

What would bony fish do in terms of ventilation in higher temperatures and why?

A

Open and close their mouths faster
Warm water has less O2 dissolved in it
With more ventilation movements, the more water is pumped over the gills to provide the same amount of oxygen

251
Q

Why would gill filaments/lamellae not provide an efficient gas exchange system on land?

A

Would dry out - no longer moist for O2 to dissolve
Would collapse and stick together, reducing the surface area for gas exchange

252
Q

Why do plants need to exchange gases?

A

For respiration and photosynthesis

253
Q

What’s the main gas exchange surface of a plant?

A

The leaf

254
Q

What is an ideal organ for exchanging gases in a plant?

A

The leaf

255
Q

What is a leaf’s structure related to?

A

Its function

256
Q

Lamina

A

Leaf blade

257
Q

Leaf blade

A

Lamina

258
Q

How is a leaf’s structure related to its function as a gas exchange surface?

A

Leaf blade (Lamina) - thin and flat with a large surface area
Diffusion pathway for gases - short

259
Q

Flowering plant

A

Angiosperm

260
Q

Angiosperm

A

Flowering plant

261
Q

What type of plant do we need to be able to label its leaves?

A

Angiosperm (flowering plant)

262
Q

Draw and label a photo micrograph of a leaf’s transverse section

A

(See notes)

263
Q

What does the lower epidermis include?

A

Guard cells

264
Q

What does the vascular bundle consist of?

A

Xylem
Cambium
Phloem

265
Q

What do the xylem, phloem and cambium make up?

A

The vascular bundle

266
Q

What are leaves responsible for?

A

Exchanging gases
Trapping light for photosynthesis

267
Q

Midrib

A

Strengthened vain in the middle of a leaf

268
Q

Strengthened vain in the middle of a leaf

A

Midrib

269
Q

What does the midrib do?

A

Carries the vascular bundle (Xylem and phloem tubes)
Carries the products of photosynthesis
Makes the leaf rigid

270
Q

Name the adaptations of leaves for photosynthesis

A

Large surface area
Thin
Air spaces in the spongey mesophyll
Cuticle and epidermis are transparent
Palisade mesophyll cells are elongated and densely arranged in layers
Palisade cells are packed with chloroplasts and arranged with their long axes perpendicular to the surface
Chloroplasts rotate and move within mesophyll cells

271
Q

Significance of a large surface area for gas exchange in leaves

A

Room for many stomata

272
Q

Significance of a leaf being thin for gas exchange

A

Diffusion pathway for gases entering and leaving is short

273
Q

Significance of air spaces in the spongey mesophyll for gas exchange in leaves

A

Reduce diffusion distance for CO2
Allows gas to circulate
Allows oxygen and CO2 to diffuse between the stomata and the cells

274
Q

Adaptations of leaves for gas exchange

A

Large surface area
Thin
Air spaces in the spongey mesophyll

275
Q

Significance of a large surface area of leaves for photosynthesis

A

Capture as much light as possible

276
Q

Significance of leaves being thin for photosynthesis

A

Light penetrates through leaf

277
Q

Significance of air spaces in the spongey mesophyll of leaves for photosynthesis

A

Allow CO2 to diffuse to the photosynthesising cells

278
Q

Significance of the cuticle and epidermis being transparent in a leaf for photosynthesis

A

Light penetrates to the mesophyll

279
Q

Significance of palisade mesophyll cells being elongated and densely arranged in layers in leaves for photosynthesis

A

Can accommodate a large number of cells
No cross walls to prevent light from penetrated through the cell = capture as much light as possible

280
Q

What’s the main photosynthetic tissue of a leaf?

A

Palisade mesophyll

281
Q

What’s the significance of palisade cells being packed with chloroplasts and ranged with their long axes perpendicular to the surface in leaves for photosynthesis?

A

Capture as much light as possible

282
Q

Significance of chloroplasts rotating and moving within mesophyll cells in leaves

A

Moves into the best position for maximum absorption of light
(For example, we see plants on windowsills angled towards the window after a few days in order to capture sunlight)

283
Q

What’s the waxy cuticle secreted by?

A

Epidermal cells

284
Q

What’s the purpose of a leaf’s waxy cuticle?

A

Stops water from evaporating from the leaf surface - reduces water loss

285
Q

What are the adaptations of the spongey mesophyll for gas exchange and why are they important?

A

Large surface area - gaseous exchange
Air spaces - reduce diffusion distance for CO2, allow O2 and CO2 to diffuse between the stomata and the cells
Moist - absorb CO2 and dissolve gases
Stomata pores on the base of the leaf - allow gases to enter the air spaces (O2 out, CO2 in) + water leaves through the stomata

286
Q

Where are the stomata pores on a leaf?

A

On its base

287
Q

What do stomata pores do?

A

Allow gases to enter the air spaces
Allow water to leave

288
Q

Do plants require oxygen?

A

Yes

289
Q

Where do plants obtain the gases they need through?

A

Through their leaves

290
Q

Which gases to plants require and for what?

A

O2 - respiration
CO2 - photosynthesis

291
Q

What do plants do in terms of photosynthesis and respiration?

A

Do both simultaneously (O2 produced and taken in)

292
Q

What gas exchange generally occurs in a plant in the daytime?

A

O2 out, CO2 in

293
Q

What happens to plants in terms of gas exchange when it’s light?

A

Use up a lot of CO2
O2 is produced as waste when photosynthesising
Cells are still respiring, but not using much O2

294
Q

What’s produced as waste when plants photosynthesise?

A

O2

295
Q

What is a lot of used when photosynthesising?

A

CO2

296
Q

What gas exchange occurs when it’s dark?

A

O2 in, CO2 out

297
Q

What do plants do in terms of gas exchange when it’s dark?

A

No light to photosynthesise, so plant cells are only respiring

298
Q

Why are plant cells only respiring when it’s dark?

A

No light to photosynthesise

299
Q

What’s the average gas exchange that occurs in plants?

A

Plants produce more O2 than they use up

300
Q

Stomata definition

A

Pores on lower leaf surface and their aerial parts of a plant bounded by two guard cells, through which gases and water vapour diffuse

301
Q

What are stomata bounded by?

A

Guard cells

302
Q

What do guard cells do?

A

Bind stomata

303
Q

What diffuses through stomata?

A

Gases
Water vapour

304
Q

Draw and label an open stoma

A

(See notes)

305
Q

Draw and label a closed stoma

A

(See notes)

306
Q

What are guard cells?

A

Specialised cells either side of the stomata

307
Q

Word for 1 v.s plural stomata

A

Stoma = 1
Stomata = 2+

308
Q

What do guard cells have that other epidermal cells don’t and why is this?

A

Chloroplasts
Very metabolically active and produce carbohydrates and store it as starch

309
Q

Describe the walls of guard cells

A

Thick inner wall
Thin outer wall

310
Q

What happens to a guard cell when it swells and why?

A

Becomes a curved sausage when it swells to open the stomata pore due to it having a thick inner wall

311
Q

When do guard cells become like curved sausages (lol) and why? What does this lead to?

A

When they swell due to the thick inner wall
Stomatal pore opens

312
Q

What can guard cells do?

A

Change shape to open and close the stomata

313
Q

How do guard cells open and close the stomat

A

Change shape

314
Q

What does guard cells opening and closing the stomata do?

A

Helps control gas exchange and water loss

315
Q

When would the stomata open?

A

During the day - needs to actively photosynthesise and take CO2 in

316
Q

Describe the steps of stomatal opening

A

During the day, if light intensity is sufficient, potassium ions (K+) are pumped, by active transport, into the guard cells
As a result, stored starch is converted into malate (which is soluble…)
This lowers the water potential (becomes more negative)
Water enters by osmosis down a water potential gradient
The guard cells swell and become turgid and curve apart because their outer walls are much thinner than their inner walls
This opens the stomatal pore, allowing gas exchange

317
Q

Is starch soluble or insoluble? what does this mean?

A

Insoluble - lots an be stored

318
Q

Is malate soluble or insoluble and what does this mean?

A

Soluble
The water potential of the cell goes down when its released

319
Q

When does stomatal closure occur?

A

At night, with low light intensities an we also want to avoid water loss

320
Q

Describe the process of stomatal closure

A

When light intensity is too low for photosynthesis, potassium ions diffuse don a concentration gradient out of the guard cells
Malate is converted back into starch by condensation reaction
The water potential of the guard cell increases (becomes less negative)
Water leaves the guard cells by osmosis
The guard cell becomes flaccid - this closes the stomatal pore
This prevents gas exchange but also reduces water loss

321
Q

What does the closure of the stomatal pore lead to?

A

The prevention of gas exchange
Reduces water loss

322
Q

What do guard cells do in terms of water loss?

A

Reduce (not avoid)

323
Q

At which point is the cartilage adapted so that the trachea doesn’t collapse?

A

When breathing in

324
Q

What do cilia move from the lungs?

A

Mucus

325
Q

Why is having internal lungs an essential adaptation to a terrestrial mode of life?

A

Prevents water and heat loss

326
Q

How is a concentration gradient maintained between the alveolar air and blood?

A

Ventilation
Brings fresh oxygen to the alveoli and removes CO2

Circulation
Removed oxygen from the alveoli and brings CO2

327
Q

What does a surfactant ACTUALLY do?

A

Decreases surface tension between fluid molecules
Reduces cohesive forces
Stabilises alveolar wall
Prevents alveolar wall from collapsing and sticking together

328
Q

What does water loss in plants occur via?

A

Transpiration

329
Q

Transpiration

A

The evaporation of water vapour from the leaves of the plant through stomata into the atmosphere

330
Q

Why do multicellular organisms have both a good blood supply and a ventilation mechanism?

A

To maintain a concentration gradient

331
Q

How do the lungs of both reptiles and birds work generally?

A

Sac-like and act like bellows

332
Q

What do insects exchange gases with directly and why?

A

Tissues
Have no blood or pigments like haemoglobin

333
Q

What help reduce water loss in insects?

A

Chitin and spiracles

334
Q

How do spiracles prevent water loss?

A

Can close

335
Q

Name 3 adaptations for gas exchange exclusive for insects?

A

-tracheal system provides a large surface area
-tracheole walls are thin
-tracheole ends filled with fluid (dissolve gases)

336
Q

How are insects adapted for dry environments?

A

Spiracles can close
Tubes lines with chitin
Both prevent water loss

337
Q

Which part of the lungs become restricted and inflamed during an asthma attack?

A

Bronchioles

338
Q

What’s it important to note about the concept of water and heat loss due to internal gas exchange surfaces?

A

It’s only REDUCED, not prevented

339
Q

Why do the muscle fibres of the tracheoles of an insect have a small diameter?

A

To ensure a short diffusion pathway to supply sufficient oxygen

340
Q

Features of fish gills for efficient gas exchange

A

Large surface area (for diffusion)
Thin (short diffusion pathway)
Permeable
Good blood supply

(NOT moist)

341
Q

How have fish overcome the problem of water being a dense medium with relatively low oxygen content?

A

Forced over the gill by ventilation mechanisms
Unidirectionally
Counter-current flow = concentration gradient is maintained across the entire gill plate

342
Q

Draw a graph for counter-current flow, including arrows for the direction of flow of water and blood

A

(See notes)

343
Q

How is a concentration gradient maintained in mammas gas exchange surfaces?

A

Ventilation
Takes oxygen away from the gas exchange surface

344
Q

Standard deviation

A

How dispersed data is in relation to the mean

345
Q

What does a high value for standard deviation represent?

A

That data are more spread out from the mean

346
Q

What does a low value for standard deviation represent?

A

That data are more clustered around the mean

347
Q

Adaptations of bony fish for efficient respiration

A

Gills have a large surface area due to there being 100s of gill filaments on each gill
Gills are thin = reduced diffusion distance
Gills are permeable
Gills receive a good blood supply
Ventilating mechanism

348
Q

How come the gills of a fish have a large surface area?

A

There’s 100s of gill filaments on each gill

349
Q

How do the abdomen movements of an insect link to its ventilation?

A

Abdomen movements cause changes in pressure
= air movement through tracheal system

350
Q

What does water loss from the stomata cause and what does this lead to?

A

Tension
Water pulled up via xylem

351
Q

What have the lowest metabolic rate - amphibians or mammals?

A

Amphibians

352
Q

How are stomata different to epidermal cells?

A

Chloroplasts
Unevenly thickened cell walls (thin outer wall, thick inner wall)

353
Q

What does stomata closure do to water loss?

A

Reduces it (doesn’t stop it)

354
Q

How come gill filaments of fish are thin?

A

1 cell thick epithelium

355
Q

What does having more cells tend to mean in an organism?

A

Higher metabolic demand

356
Q

What type of organisms have higher metabolic demands?

A

Multicellular

357
Q

What does being cylindrical do to a surface area to volume ratio?

A

Increases it

358
Q

What do Collenchyma have in their walls?

A

Uneven thickening of cellulose

359
Q

What do Collenchyma do?

A

Give support to short- lived structures

360
Q

Does Collenchyma contain lignin?

A

No

361
Q

How can we identify Collenchyma?

A

Star shaped structures between cells

362
Q

What often occurs to Collenchyma when preparing it and why?

A

Thinner areas of the cell walls often breaks as the cells are dehydrated when preparing

A level Biology (26 decks)

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