biology-Diffusion and osmosis

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What is diffusion?
when a chemical travels from an area of high concentration to an area of low concentration. It doesn't need energy and will allow any mobile or soluble materials to move.Surfaces where diffusion takes place often have a greatly increased surface area
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in terms of diffusion, what happens the bigger difference from high to low concentration?
the bigger the difference, the bigger the diffusion gradient.. the faster the rate of diffusion
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what can diffusion do to oxygen?
oxygen is a gas, and so the particles can move and so it can pass from the air sac into the blood by diffusion
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what can diffusion do to some products of digestion?
some products of digestion are soluble in water and so can move out of the gut into the blood by diffusion
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What is osmosis?
this a special case of diffusion where the molecules that move are water.Osmosis is the movement of water from a more dilute (more water) to a more concentrated solution(which has less water) through a partially permeable membrane.
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in osmosis, what is the selectively permeable membrane in plant and animal cells?
the cell membrane
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explain osmosis in plant cells
the plant cell wall holds the cell in shape and prevents it broom bursting when water enters by osmosis. Water moves into cell and out of cell by osmosis.
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what does the word isotonic mean?
equal concentrations
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what does hypotonic mean?
low concentration of solute or more dilute solution
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what does hypertonic mean?
high concentration of solute or more concentrated solution
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explain osmosis in animal cells
animal cells do not have cell walls and so the effect of osmosis is more dramatic
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explain the model of osmosis
visking tubing-thin,porous,artificial membrane that allows molecules through according to size.Molecules that too big to pass through the pores-not able to pass through.Can be used to demonstrate osmosis as a physical process that does need a living
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What is active transport?
if a substance is need in a cell it can be moved against the concentration gradient-from a lower to a higher concentration. This needs energy.
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where does active transport take place?
in the root hair cells in the uptake of minerals from soil and in the update of glucose of the small intestine into the blood
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where does diffusion occur?
in many living systems,for example the movement of carbon dioxide and oxygen in the lungs and leaves.
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what do you need for osmosis to happen?
two solutions with different concentrations,a partially permeable membrane to separate them,partially permeable membranes let some substances pass through them but not others.
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describe a dilute solution of sugar
contains a high concentration of water (solvent) and a low concentration of sugar (the solute).A concentrated sugar solution contains a relatively low concentration of water+a high one of sugar
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does diffusion move up or down a concentration gradient?
down. concentration gradients require energy
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does osmosis move up or down a concentration gradient?
down
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does active transport move up or down a concentration gradient?
up
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give an example of active transport
glucose from the intestine into the blood
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what is usually used during experiments for osmosis?
a visking tube
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how is osmosis a two way process?
if the concentration inside and outside of cell is the same, osmosis doesn't stop but the movement in and out of the cell is balanced and there is no net movement of water
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in terms of diffusion, what happens the bigger difference from high to low concentration?

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the bigger the difference, the bigger the diffusion gradient.. the faster the rate of diffusion

Card 3

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what can diffusion do to oxygen?

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Card 4

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what can diffusion do to some products of digestion?

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Card 5

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What is osmosis?

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