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aqa a-level biology a > Pack 7 - Exchange > Flashcards

Pack 7 - Exchange Flashcards

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1
Q

List 4 factors affecting diffusion

A

Surface area

Diffusion distance

Concentration gradient

Temperature

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2
Q

How do you calculate the surface area of a cube?

A

6side²

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3
Q

How do you calculate the volume of a cube?

A

side³

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4
Q

As an object gets larger which is happening to its surface area to volume ratio?

A

Decreases

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5
Q

What structures are present in the small intestine that help absorption?

A

Villi

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6
Q

Why do elephants need large ears?

A

To have a larger surface area:volume ratio for increased heat loss

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7
Q

Do animals with a larger SA:Vol require a higher or lower rate of metabolism?

A

Higher: higher SA:Vol leads to more heat loss

More respiration is therefore required to maintain the animal’s temperature

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8
Q

Define respiration

A

The release of energy (ATP synthesis) from food

eg. glucose/fats and proteins if desperate

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9
Q

What is respiration with O2 called?

A

Aerobic respiration

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10
Q

What is respiration without O2 called?

A

Anaerobic

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11
Q

What is the word equation for aerobic respiration?

A

Glucose + oxygen -> CO2 + H20 + Energy (ATP and heat)

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12
Q

What is the word equation for anaerobic respiration?

A

Glucose -> lactate + energy (ATP and heat)

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13
Q

Which type of respiration produces more ATP?

A

Aerobic

Aerobic Anaerobic
38 ATP : 2 ATP

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14
Q

Do all organisms need to respire?

A

Yes

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15
Q

List 6 features of an effective gas exchange surface

And why (think Fick’s law)

A
  1. Moist - To dissolve gases
  2. Large SA:Vol - SA
  3. Thin - DD
  4. Permeable to gases - To allow gas exchange
  5. Ventilation - CG
  6. Movement of internal medium - CG
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16
Q

What will happen to the rate of diffusion if diffusion distance is increased?

A

It will fall

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17
Q

What will happen to the rate of diffusion if SA:Vol is increased?

A

It will increase

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18
Q

What will happen to the rate of diffusion if the concentration gradient is decreased?

A

It will fall

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19
Q

Give an example of a single-celled protoctista?

A

Amoeba

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20
Q

How do amoeba get their O2 in and CO2 out?

A

Simple diffusion

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21
Q

Why do amoeba not need a specialised gas exchange system?

A

They are single-celled and therefore have a small diffusion distance for gases to travel

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22
Q

Why do bigger animals develop specialised respiratory surfaces/transport systems?

A

Most cells are far from the surface and so receive inadequate oxygen

Many larger animals have an increased metabolic rate, increasing oxygen demand

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23
Q

Give an example of a respiratory pigment

A

Haemoglobin

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24
Q

Give an example of a ventilation movement

A

Breathing

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25
Q

Why is spongy mesophyll made up of irregular cells?

A

Increased surface area due to more exposed CSM

Therefore a faster rate of diffusion

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26
Q

Do plants photosynthesise or respire at a higher rate at night?

A

Respire

Lack of sunlight means ineffective/no photosynthesis

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27
Q

Do plants photosynthesise or respire at a higher rate at in the day?

A

Photosynthesise

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28
Q

What is the function of stomata?

A

Open in light/close in dark

When open gas exchange is able to occur through them
-For metabolic needs eg. photosynthesis, respiration

Close (shrunken guard cells) if the plant looses too much water
-Reducing water loss through transpiration through open stomata

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29
Q

If a leaf is losing too much water, what will it do and how will this affect gas exchange in the leaf?

A

Close the stomata

Reduce gas exchange
-lower volume of gases diffusing in and out of the leaf

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30
Q

What is transpiration?

A

Evaporation of water from a plant leaf

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31
Q

Give 4 factors that will increase transpiration rate

A

Hot

Windy

Dry

Sunny

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32
Q

Define hydrophyte

A

Live in environment with LOTS of water availability

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33
Q

Define mesophyte

A

Live in environment with MODERATE water availability

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34
Q

Define xerophyte

A

Live in environment with LOW water availability

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35
Q

How does water potential gradient affect water loss from stomata?

A

More water is lost when there is a greater water water potential gradient between the inside and outside of the stomata

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36
Q

List 5 ways xerophytic plants are adapted to reduce water loss

And link to Fick’s law

A

Thick cuticle - DD
Rolled up leaves - CG (traps moist air on inside)
Hairy leaves - CG (traps moist air)
Stomata on pits/grooves - CG
Reduced SA:Vol of the leaves - SA (traps moist air)

Trapping moist air lowers the ψ gradient, lowering rate of diffusion, reducing water loss from the plant

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37
Q

Why do insects have a waterproof cuticle?

A

Water evaporates from their surfaces as they live on land and can become easily dehydrated

They conserve water by having waterproof coverings

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38
Q

How do insects respire?

A

Spiracles (pores) on their thorax and abdomen lead to

Tracheae (strengthened rings of chitin) dividing into

Tracheoles which bring atmospheric air directly into respiring cells

The spiracles can be opened and closed by valves which allow the insects to control water loss

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39
Q

What feature of respiratory surfaces is missing in an insect?

A

Permeable surface (exoskeleton)

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40
Q

How does oxygen enter the tracheal system?

A

Moving down the concentration gradient

Ventilation - moving muscles means air is taken in via the spiracles in the abdomen

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41
Q

Why are insects small?

A

To have short diffusion pathways for efficient respiration

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42
Q

What is the effect of exercise on the gas exchange of insects?

A
  1. Anaerobic respiration takes place
  2. Lactate increases
  3. Ψ decreases in muscle
  4. Water enters muscle via osmosis
  5. Air drawn into tracheoles
  6. Increases SA for gas exchange
  7. O2, CO2 diffuse faster through gases than liquids
  8. Increased respiration
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43
Q

What is the advantage of water entering insect’s muscle cells from the tracheoles?

A

O2, CO2 diffuse faster through gases than liquids, increasing respiration

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44
Q

How do insects limit water loss?

A

Hard, impermeable exoskeleton - reduces water loss from the whole body

Small SA: Vol - lower rate if diffusion of water

Valves around the spiracles - shut to reduce water loss from spiracles SA:Vol

Setae around the spiracles - hairs that trap most air reducing the concentration gradient therefore slower evaporation of water

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45
Q

What is Fick’s Law?

A

Diffusion rate ∝ Conc. Grad. × Surface Area

Diffusion Distance

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46
Q

Which areas of Fick’s Law do you want to keep large and small?

A

Big × Big

Small

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47
Q

How do fish move water over the gill?

A

Bony fish have four pairs of branchial arches supporting gill lamellae. These are covered by a muscular flap - the operculum.

  1. Fish open their mouth and lower the floor of the buccal cavity
  2. This increases the volume and decreases the pressure in the mouth, compared to outside, and so water enters down the pressure gradient
  3. The operculum is closed at this stage
  4. Then the fish closes its mouth and raises the floor of the mouth
  5. This has the effect of decreasing the volume and increases the pressure compared to outside and so forces water through the gills and out through the operculum
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48
Q

Why does water flow over the gills in only direction (and not pass in and out of the gills as air does in the lungs of a mammal)?

A

Water is more dense than air

49
Q

What does afferent mean?

A

Conducted/conducting inwards or towards

50
Q

What does efferent mean?

A

Conducted/conducting outwards or away from something

51
Q

What is counter-flow system?

A

The blood and water flow in opposite directions.

This ensures a constant concentration gradient

Across the whole lamellae.

Present in bony fish for more efficient aerobic respiration

52
Q

What shape is a counter-flow graph?

Distance across lamellae by % O2 in blood/water

A

blood \ water

53
Q

What shape is a parallel flow graph?

Distance across lamellae by % O2 in blood/water

A

\____

/

54
Q

What is the new spec name for a gill plate?

A

Gill lamellae

55
Q

What are the two processes that make up respiration?

A

Cellular respiration

Gas exchange

56
Q

Summarise cellular respiration

A

The process by which ATP is produced

57
Q

What does cellular respiration involve?

A
  1. The breakdown of food (glucose and lipid) to release energy
  2. Some of this energy is used to make ATP from ADP and Pi
  3. The rest of the energy is released as heat
58
Q

What gas exchange occurs in the mitochondria during aerobic respiration?

A

Mitochondria use O2 and release CO2

59
Q

What is the word equation for aerobic respiration?

A

Glucose + Oxygen -> Water + Carbon Dioxide (+Energy; ATP + Heat)

60
Q

What do increased organism size lead to?

A

Increased metabolic rate
∴ increased oxygen demand

This leads to:

  1. A specialised gas exchange system
  2. A transport system - usually a blood system
61
Q

Give five characteristics of an effective respiratory surface

A
  1. Moist
  2. Permeable
  3. Thin
  4. High SA:Vol
  5. Maintained conc. grad.
62
Q

What is the function of the larynx?

A

Allows air in and out and vocal cords to dilate

63
Q

What is the role of the rings of cartilage in the trachea?

A

To keep the trachea open

64
Q

What is the role of the bronchi and bronchioles?

A

To get air to the alveoli and back out again

65
Q

Describe the structure of the alveoli

A

Like a bag of grapes

66
Q

What is occurring in the alveoli?

A

Gaseous exchange

67
Q

What type of epithelium are alveoli and capillary cells made up of?

A

Squamous

68
Q

Describe squamous (cells)

A

Very thin, flattened

69
Q

How is squamous epithelium ideally suited to allow gas exchange?

A

Thin - short diffusion distance

Large SA: Vol - more diffusion at one time

70
Q

Why is it an advantage to slow the blood down in capillaries?

A

More time for diffusion (CO2 and O2)

71
Q

How are the lungs well-adapted for effective gas exchange

A
  1. Capillaries and alveoli lie very close to one another (resulting barrier approx. 0.3μm) - Short diffusion distance
  2. Both lungs possess many alveoli (approx. 700 million) - large surface area
  3. Capillaries are very small ∴ RBCs must squeeze through, slowing the blood flow
72
Q

What is the function of surfactant?

A

A detergent-like substance reducing the epithelial moisture layer’s surface tension, preventing the alveolar walls bring pulled together and collapsing

73
Q

What is a macrophage?

A

A type of phagocyte, WBCs

74
Q

Why is it important that macrophages a present in the alveoli?

A

They destroy pathogens in the air

75
Q

Define residual volume

A

The amount of air that remains in the lungs after the most forcible expiration possible

76
Q

Define dead space

A

The air that does not reach the alveoli (stays in eg. trachea, bronchi and bronchioles)

77
Q

How is partial pressure written?

A

pO2 or pCO2

Units kPa

78
Q

Define partial pressure (for in an exam)

A

It is equivalent to concentration

79
Q

How does oxygen diffuse inside the alveoli?

A

Down the pO2 gradient

80
Q

Describe the six stages in the diffusion of oxygen from the alveolus to the red blood cells

A
  1. Diffuses through alveolar space
  2. Dissolves in mucus
  3. Diffuse through alveolar cell open bracket epithelium close bracket
  4. Diffuses through capillary cell
  5. Diffuses through plasma
  6. Diffuses through semi permeable membrane of red blood cells; joins with haemoglobin to form oxyhaemoglobin
81
Q

Does the concentration of CO2 have any effect on the rate of diffusion of O2?

A

No. Both gases travel independently of each other and in opposite directions.

Answer exam questions only about the gas that is asked

82
Q

Why is O2 transport on the alveoli not as efficient as it seems?

A
  1. Some blood entering the lungs does not go into the alveolar capillaries and therefore does get oxygenated
  2. Some alveoli are under-ventialted
83
Q

Define inspiration

A

When air is breathed in

84
Q

Define expiration

A

When air is breathed out

85
Q

What happens when we inspire?

A

The diaphragm contracts and flattens

The external intercostal muscles contract moving the ribs up and out

The thorax volume increases, decreasing the pressure below atmospheric

Air moves into the lungs down the pressure gradient

86
Q

What happens when we expire?

A

The diaphragm relaxes and bows upward

The internal intercostal muscles contract moving the ribs down and in

The thorax volume decreases, increasing the pressure above atmospheric

Air moves out of the lungs down the pressure gradient

87
Q

What is the stretchy nature of the lungs called?

A

Natural elasticity

88
Q

What muscles are used for forced expiration but not gentle breathing

A

Abdominal muscles

These contract, pushing the abdominal organs up against the diaphragm.

Thorax volume decreases
Lung pressure increases more

89
Q

What is the function of pleural membranes?

A

Surrounds the pleural cavity around the lungs which is filled with pleural fluid.

The outer PM is attached to the inner wall of the thorax

The inner PM covers the lungs

90
Q

What is the function of pleural fluid?

A

Allows pleurae to slide over one another easily during breathing

91
Q

How would you describe the internal and external intercostal muscles?

A

Antagonistic

92
Q

What are the short term effects of exercise on breathing?

A

Faster rate
Deeper breaths
Increased oxygen in
Increased carbon dioxide out

93
Q

What are the long-term effects of regular exercise?

A

More alveoli
More capillaries
Diaphragm and intercostal muscles become stronger

94
Q

What is the equation for pulmonary ventilation?

A

Pulmonary ventilation (cm3min-1) = tidal volume (cm3) × breathing rate (min-1)

95
Q

Why will pulmonary ventilation increase with exercise?

A

Tidal volume and breathing rate are increased

96
Q

Define pulmonary ventilation

A

The product of tidal volume multiplied by breathing rate

97
Q

Define tidal volume

A

Volume breathed in and out in one cycle

98
Q

Define breathing rate

A

Number of breaths in a minute

99
Q

How does blood flow relate to Fick’s law?

A

Maintained concentration gradient

100
Q

How does ventilation relate to Fick’s law?

A

Maintained concentration gradient

101
Q

How does a large number of alveoli with many internal walls relate to Fick’s law?

A

Increased SA:Vol

Decreased diffusion distance

102
Q

How does a large number of capillaries relate to Fick’s law?

A

Increased SA:Vol

Decreased diffusion distance

103
Q

How does Plaza now being separated by only two cells (alveoli and capillary) relate to Fick’s law?

A

Decreased diffusion distance

104
Q

Does correlation mean causation?

A

No as there may be other contributing factors

105
Q

List the 5 major risk factors for lung disease

A 
Smoking
Air pollution
Genetic disposition
Infections
Occupation
106
Q

What are the causes/risk factors of fibrosis?

A

Unclear. Evidence suggests reaction to microscopic lung injury to which some are genetically more susceptible

107
Q

What are the symptoms of fibrosis?

A

Shortness of breath

  • reduced elasticity of lungs: DD SA
  • lungs filled with fibrosis tissue: lower lung capacity

Chronic dry cough
- fibrous tissue blocks airway: cough reflex to attempt to move it (but immovable)

Chest pain

  • pressure due to fibrous tissue
  • damage and scarring due to coughing

Weakness and fatigue
- less oxygen intake therefore reduced cellular respiration and energy release

108
Q

What are the long term effects of fibrosis?

A

Scars
- longer diffusion pathways

Reduced lung elasticity
- difficult to expire spent air

109
Q

What are the causes/risk factors of asthma?

A

Localised allergic reaction

  • air pollution
  • exercise
  • cold air
  • infection
  • anxiety
  • stress
110
Q

What are the symptoms of asthma?

A

Causes white blood cells to release histamine which

  • inflames the linings of the Airways
  • causes the epithelium to secrete more mucus
  • causes fluid from the capillaries to enter the airways
  • causes the muscles around the bronchioles to contract and constrict airflow

Breathing difficulty

  • bronchi constricted
  • lungs inflamed; filled with mucus and fluid

Wheezing
- air passing through constricted bronchi

Tight feeling in the chest
- unable to ventilate the lungs due to constrictions

Coughing
- attempt to clear the obstructed airways

111
Q

What are the long-term consequences of asthma?

A

Restricted ventilation
Reduced cellular respiration
Lower concentration gradient across alveoli cells

112
Q

What are the causes/risk factors of emphysema?

A

Elastin protein in lungs becomes permanently stretched

  • cannot force out spent air
  • surface area of the alveoli becomes reduced
  • fewer alveoli
  • thicker alveoli walls
  • larger air space in each alveoli
113
Q

What are the symptoms of emphysema?

A

Shortness of breath

  • constant stale air
  • lungs permanently inflated
  • reduced surface area meaning the rate of diffusion therefore less oxygen available for cellular respiration

Chronic cough
- reflux cough to remove damaged tissue and mucus that are not removable

Blue skin tone
- low blood oxygen levels

114
Q

What are the long-term consequences of emphysema?

A

Restricted ventilation
Lower concentration gradient across alveoli cells
Longer diffusion distances inside lungs
Reduced cellular respiration

115
Q

What are the causes/risk factors of tuberculosis?

A

Mycobacterium tuberculosis or mycobacterium bovis
- bacteria attach the droplets of water/mucus from an infected person

Varying vaccination rates
Immigration and different strains
Living conditions
Close contact
Residential facilities
Reduced immunity
Cows
Certain countries
116
Q

What are the symptoms of tuberculosis?

A

Bacteria growing up a part of the lungs (where there is plenty of oxygen)
White blood cells accumulate to ingest the bacteria
Primary infection
- inflammation and enlargement of lymph nodes in the lungs
- occurs in children
Few symptoms and infection is controlled but the bacteria remain

117
Q

What are the long-term consequences of tuberculosis?

A

Post primary tuberculosis

  • bacteria re-emerge
  • occurs in adults

Bacteria creates cavities in the lungs
- the lung repairs itself with scar tissue

Sufferer coughs up damaged lung tissue and blood containing bacteria

The infection can spread to the rest of the body and be fatal

118
Q

Define pulmonary

A

Relating to the lungs

119
Q

Why is an excess of carbon dioxide in the body a problem?

A

Creates carbonic acid

Carbonic acid denatures enzymes

H20 + CO2 -> H2CO3

aqa a-level biology a (5 decks)

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