Biology Revision-Exchange

Why do fish use a one way flow of water across the gill?
It would be much harder to move water back in the opposite direction so a two way flow would waste lots of energy and be very inefficient
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How do the gills fulfil a large surface area?
4 pairs of gills, each with lots of lamellae/ Each lamellae has lots of gill plates (secondary lamellae)
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How do the gills fulfil a short diffusion distance?
Surface of gill plates are 1 cell thick/ Cells in epithelium are flattened/ Capillary walls are 1 cell thick/ Capillary wall cells are flattened/ Capillary wall next to epithelium (so very close to water)
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What is the role of cilia?
Cilia prevents foreign bodies opening/ Cilia increases humidity around the opening, decreasing water potential gradient.
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Insects- efficient gas exchange- large surface area?
Lots of tracheae
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Insects- efficient gas exchange- Small diffusion distance?
Insects have an upper size limit so that the diffusion distance in any insect is small/ Gases diffuse straight to respiring tissues.
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Insects- efficient gas exchange- steep concentration gradient?
Gases move in both directions by diffusion - gradient maintained by respiring tissues - Low O2/High CO2 at respiring tissues. Ventilation of tracheae -movement of muscles creates mass movement of air -flying increases ventilation.
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Insects- efficient gas exchange-Moist surface?
Hairs trap a layer of moisture around the spiracles
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What are the methods insects use to reduce water loss?
Waterproof exoskeleton/ valves over spiracles so they can be shut/ Hairs around spiracles-trap a moist layer of air(also prevent entry of dust/parasites)
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What are xerophytes?
Plants adapted to a dry habitat
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What is the function of the xylem?
To transport water and mineral ions
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leaf- efficient gas exchange-steep concentration gradient?
Cells are using gases therefore maintaining a diffusion gradient/ No ventilation
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leaf- efficient gas exchange-large surface area?
Large palisade cells with lots of chloroplasts/ Intercellular spaces mean that lots of cells in contact with atmospheric gases./ Leaves have a large surface area
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leaf- efficient gas exchange-small diffusion distance and partially permeable?
Thin eaves. Gases can diffuse into and out of cells
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What ways do plants reduce water loss?
Waxy cuticle on top of leaf/ Close stomata when short of water/ Hairs around stomata/ Stomata in pits/ Leaves which can roll up to protect stomata
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What is pulmonary ventilation?
Pulmonary ventilation is the total volume of air that is moved into the lungs during one minute.
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What is tidal volume?
The volume of air normally taken at each breath when the body is at rest
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What is ventilation rate?
The number of breaths taken in 1 minute
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What is the formula for pulmonary ventilation?
tidal volume x ventilation rate
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In the lungs oxygen passes from the alveoli to the blood. Describe and explain the features that make this process rapid and efficient?
Large surface area/ Thin alveolar wall/one cell thick/ flattened cells in alveolar/ Ventilation of alveoli keeps oxygen concentration high/ Maintains diffusion gradient
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Card 2

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How do the gills fulfil a large surface area?

Back

4 pairs of gills, each with lots of lamellae/ Each lamellae has lots of gill plates (secondary lamellae)

Card 3

Front

How do the gills fulfil a short diffusion distance?

Back

Preview of the front of card 3

Card 4

Front

What is the role of cilia?

Back

Preview of the front of card 4

Card 5

Front

Insects- efficient gas exchange- large surface area?

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