Gas Exchange/Limiting Water Loss

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What 3 factors increase the efficency of gas exchange?
A large surface area, a concentration gradient, a short diffusion pathway
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Why is gas exchange efficent in single celled organisms?
Because they have a large surface area to volume ratio due to being small in size. They only have a cell surface membrane for gas to travel across, this implies that the diffusion pathway is short
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What are spiracles?
They are tiny holes on the body of an insect.
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What the internal network of tubes called inside an insect?
Trachae
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What are the smaller tubes that the trachae split into called?
Tracheoles
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What are the 3 ways in which the respiratory gases move in and out of the tracheal system?
Along a diffusion gradient, Mass transport and the end of the tracheoles are filled with water.
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Why do the tracheoles have water in them?
Water moves into the cell from the tracheoles by osmosis, so the volume of water in the end of the tracheoles decreases, this draws air further into them.
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What is mass transport?
The contraction of muscles in insects can squeeze the trachea enabling mass movements of air in and out.
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Why do insects keep their spiracles closed for much of the time?
To prevent water loss.
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How are the hairs surrounding the spiracles helpful?
They help maintain humidity around the opening, this ensures that there is a lower concentration gradient of water vapour, so less water can be lost from the insect by evaporation
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Why is the body surface of a fish not adequate to supply and remove respiratory gases?
Fishes are large, therefore meaning they have a small surface area to volume ratio.
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Where are the gills located on a fish?
Behind the head within the body of the fish.
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How are the gill filaments arranged?
They are stacked up in a pile.
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What is the function of the gill lamellae?
They increases the surface area of the gills.
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What is countercurrent flow?
The blood within the fish is moving the opposite direction the the water on the outside of the fishes body.
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Why is countercurrent flow needed for maximum gas exchange?
So that there is a constant concentration gradient meaning that oxygen can be continuously absorbed from the water.
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What are stomata?
The stomata are minute pores that occur mainly on the the underside of leaves on a plant.
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How do guard cells close the stomatal pore?
The guard cells take up water by osmosis making them turgid.
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Why is it important that a plant can close the stomatal pores?
To prevent water loss.
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What are the adaptions for rapid diffsuion in a plant?
Many small pores (stomata), numerous interconnecting air spaces that occur throughout the mespophyll, large surface area of mesophyll.
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How are plants similar to insects in terms of gas exchange?
Diffusion takes place in the gas phase and no living cell is far from the external air.
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What are the 3 adaptions that insects have evolved to prevent water loss?
Small surface area to volume ratio, Water proof coverings, Spiracles.
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How does a small surface area prevent water loss?
To minimise the area over which water is lost.
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What are xerophytes?
A species of plant that has adapted to survive in an environment with little liquid water.
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What is transpiration?
Transpiration is the process where plants absorb water through the roots and then give off water vapor through pores in their leaves.
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Why can't plants have a small surface area to volume ratio?
Because they need a large surface are to photosynthesise - so the plant is able to capture light.
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Name the 5 modifications a plant may have to prevent water loss
A thick cuticle, rolling up of leaves,hairy leaves, stomata in pits or groves, a reduced surface area to volume ratio of the leaves.
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Why must the volume of oxygen absorbed and the volume of carbon dioxide removed be large in mammals?
Because they are large organisms, they have a high body temperature which is related to them having a high metabolic and respiratory rates.
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List the correct sequence of all the structures that are passes through on its journey from the gas exchange surface of the lungs to the nose?
alveoli, bronchioles, bronchi, trachea, nose
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What are the bronchioles?
A series of branching subdivisions of the bronchi.
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What are the alveoli?
Small air sacs at the end of the bronchioles.
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Other cards in this set

Card 2

Front

Why is gas exchange efficent in single celled organisms?

Back

Because they have a large surface area to volume ratio due to being small in size. They only have a cell surface membrane for gas to travel across, this implies that the diffusion pathway is short

Card 3

Front

What are spiracles?

Back

Preview of the front of card 3

Card 4

Front

What the internal network of tubes called inside an insect?

Back

Preview of the front of card 4

Card 5

Front

What are the smaller tubes that the trachae split into called?

Back

Preview of the front of card 5
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