Biology summer revision pt 2

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  • Created by: Tiana
  • Created on: 06-06-15 19:30
Define diffusion
the movement of particles from an area of high concentration to an area of low concentration through a partially permeable membrane
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What will you find when measuring the effect of temperature on diffusion?
if temperatures are higher, the diffusing particles will have mroe kinetic energy, therefore they will move across the cell membrane faster
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what was the experiment to measure temperature on diffusion?
the visking tube experiment: to investigate whether glucose and starch molecules can diffuse through the membrane. THE TIME TAKEN FOR DIFFUSION TO OCCUR WAS QUICKEST AT THE HIGHEST TEMPERATURE
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in the experiment what managed to diffuse through the membrane?
the glucose molecules. (the starch molecules were too big)
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Define Active transport
the movement of ions or molecules across a cell membrane into a region of higher concentration (from an area of low concentration) transported by enzymes & requiring energy.
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Where does active transport take place in humans?
during the digestion of food in the small intestine. The glucose is absorbed by active transport to be passed into the bloodstream and taken around the body
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what are the three factors that affect rate of diffusion?
surface area, temperature and concentration gradient
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why does the concentration gradient affect rate of diffusion?
because the particles that diffuse move from an area of high concentration to an area of low concentration. The steeper the gradient the faster the particles diffuse.
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why does surface area affect rate of diffusion?
as body size increases the need for a higher rate of diffusion of materials into and out of the body increases.
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Define Osmosis
a net movement of water molecules from an area of high concentration to an area of low concentration; across a partially permeable membrane
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what does turgid mean?
swollen but healthy
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what does flaccid mean?
droopy
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What does plasmolysed mean?
loss of excess water
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describe osmosis in plant cells
if the cell is put into pure water, water will move into the cell. If the cell is put into a solution, with low water concentration, water will move out of the cell
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Describe an experiment to measure the rate of respiration in peas.
1 batch of dead peas, 1 batch of living peas placed in an inverted flask leaving some air in the flask (respiration requires oxygen) the results show that the living peas had a higher temp. so heat is produced by RESPIRATION
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Card 2

Front

What will you find when measuring the effect of temperature on diffusion?

Back

if temperatures are higher, the diffusing particles will have mroe kinetic energy, therefore they will move across the cell membrane faster

Card 3

Front

what was the experiment to measure temperature on diffusion?

Back

Preview of the front of card 3

Card 4

Front

in the experiment what managed to diffuse through the membrane?

Back

Preview of the front of card 4

Card 5

Front

Define Active transport

Back

Preview of the front of card 5
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