Gas Exchange

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  • Created by: EmmNat14
  • Created on: 28-04-15 16:41
what is gas exchange?
The process by which oxygen reaches cells and carbon dioxide is removed from them.
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What is Surface area to Volume ratio?
When a cell increases in size the diffusion pathway gets longer, as diffusion from the outer cell surface to the centre of the cell is slow. When the cell becomes large, diffusion will not meet the cells needs.
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which organism has the largest surface area to volume ratio?
Amoeba
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What are the features of an amoeba? (unicellular)
small size, extremely large surface area, thin membrane which provides a short diffusion pathway, semi permeable allows diffusion of gases, moist surfaces allow gases to diffuse and dissolve
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what are the features of a flat worm? (multicellular)
small size, No part of the body is far from the surface (short diffusion pathway), semi permeable membrane allows diffusion of gases, exchanges gases directly with the environment.
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What are the adaptations of earth worms?
low metabolic rate= low oxygen requirements, 5 hearts+blood pigments transport gases around the organism, Co2 is transported the opposite direction to maintain concentration gradient, elongated shape= large SA:V compared to organisms the same volum
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what must all respiratory surfaces be to maximise the rate of diffusion?
Thin- shoter diffusion pathway, Moist- gases dissolve and diffuse more easily, permeable to gases, Large surface area for diffusion
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give two functions of a reptiles ribs?
ventilation of the lungs and protection
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How does the structure of reptile lungs differ from an amphibians lung?
The lungs of a reptile have a more complex strucure that the lungs of frogs. Thye have in-growth of tissue which increases the surface area for gas exchange
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what problems are caused by living in water?
water contains less oxygen than air, the rate of diffusion is slower in water, water is a dense medium and so doesn't flow as freely
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how do fish over come the difficulty of living in water?
gaseous exchange takes place at the gills, gills are made up of many folds which provide a large surface area + the density of water prevents gills from collapsing
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what is a cartilaginous fish?
SHARKS. have a skeleton made from cartilage, live in the sea, when the mouth opens water is forced in through gill slits when the floor of the mouth is raised. Parallel flow
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what is a bony fish?
ANY FISH. Inhabit in fresh+sea water, gas exchange involves counter current flow where the blood and water flow in opposite directions to each other
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what is the structure of the gills on bony fish?
along each gill arch there are many thin lamellae and on these are gill plates therefore have large surface area for gas exchange.Blood circulates through the gill plates- allowing oxygen to diffuse in and out.
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Why is the alveoli suitable as a gas exchange surface?
large surface area for diffusion of gases, moist gases dissolve and diffuse easier, permeable so O2 and Co2 are able to diffuse + Thin short diffusion distance
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What is a surfactant?
A chemical substance which covers the surfaceof the alveoli. Surfactant readuces surface tension and prevent alveoli from sticking together and collapsing when breathing out
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How are leaves adapted for gas exchange?
The leaf blade is flat with a large surface area, the spongy mesophyll layer allows diffusion of gases of to maintain diffusion gradient, plant issues are permeated by air spaces, stomatal pores allow gas exchange to occur
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how are leaves adapted for photosynthesis?
Large surface area, leaves can orientate themselves towards the sun, thin to allow light to penetrate lower layers, cuticle and epidermis are transparent+chloroplast can rotate and move with mesophyll cells.
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What is unusual about a guard cell?
they contain chloroplasts and they have unevenly thickened cell wall
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What is the mechanism for stomatal opening?
1. potassium ions are actively transported from the epidermal cells into the guard cells 2. stored starch in the guard cells is converted to malate by enzymes 3. the water potential in guard cell is lowered. 4. guard cell becomes turgid-curve apart
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why are stomata usually open during the day and closed at night?
generally stomata open during the day and close at night in response to light levels. Co2 levels, temperature, water availability can trigger stomatal opening or closure
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Why are birds ventilation a lot more efficient than other vertebrates?
In bird ventilation is assisted by system of air sacs connected to lungs. Breathing in fresh air, i passes through the respiratory in one direction only to the posterior air sacs and then the lungs then the anterior and then exits through the trachea
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why are insects gas exchange different to other animals?
because they don't use blood to transport oxygen. Air diffuses into the insect through paired holes called spiracles running along each side of the body. The spiracles lead to a system of branched chitin lined air tubes called trachea.
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Other cards in this set

Card 2

Front

What is Surface area to Volume ratio?

Back

When a cell increases in size the diffusion pathway gets longer, as diffusion from the outer cell surface to the centre of the cell is slow. When the cell becomes large, diffusion will not meet the cells needs.

Card 3

Front

which organism has the largest surface area to volume ratio?

Back

Preview of the front of card 3

Card 4

Front

What are the features of an amoeba? (unicellular)

Back

Preview of the front of card 4

Card 5

Front

what are the features of a flat worm? (multicellular)

Back

Preview of the front of card 5
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