life processes cont 15-

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  • Created by: sophie_kk
  • Created on: 18-12-19 17:30
practical: démonstration that heat is produced by respiration
1. peas soaked in water for 24 hours so they can germinate 2. second batch of peas is boiled to kill them 3. each set of peas is washed in bleach solution to kill any bacteria 4. peas are rinsed twice in distilled water to remove any bleach
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cont
5. placed inside a vacuum flask with some air - vacuum flask insulates its contents, so any small temp change can be measured 6. seeds produce co2 which is denser than air - inverted flask and cotton wool allow it to escape, otherwise it could kill
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cont
the peas 7. left for a couple of days, with the temp at start and end measured
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diffusion
the net movement of particles from an area of high concentration to an area of low concentration down a concentration gradient
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factors that affect rate of diffusion
concentration gradient - diffusion occurs quicker when there is a steep gradient (big difference in concentration between 2 areas) 2. surface area to volume ratio - larger area in proportion to the volume will increase the rate 3. distance - rate is
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cont
decreased if the distance is greater 4. temp-higher temp will provide particles with more kinetic energy, so the rate will be faster
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agar
jelly sued for growing cultures of bacteria - with a consistency similar to cytoplasm, and has a high water content
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practical : demonstration of diffusion in jelly
1. three cubes of different sizes (of agar) with side lengths of 2cm, 1cm and 0.5cm 2. they are carefully dropped into a beaker of fillet hydrochloric acid (cubes had previously been dyed purple with potassium permanganate solution) 3. the time taken
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cont
for each cube to turn colourless is noted, and the cube with the largest surface area to volume ratio will turn colourless fastest
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active transport
movement of substances against a concentration gradient, using energy from respiration
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osmosis
the net movement of water from dilute solution to a more concentrated solution across the partially permeable cell membrane
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adapted
when a cells structure is specially suited to a function
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Card 2

Front

cont

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5. placed inside a vacuum flask with some air - vacuum flask insulates its contents, so any small temp change can be measured 6. seeds produce co2 which is denser than air - inverted flask and cotton wool allow it to escape, otherwise it could kill

Card 3

Front

cont

Back

Preview of the front of card 3

Card 4

Front

diffusion

Back

Preview of the front of card 4

Card 5

Front

factors that affect rate of diffusion

Back

Preview of the front of card 5
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