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Slide 1

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B4 - Revision…read more

Slide 2

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Lock & Key theory:
1) An enzyme substrate can only fit Catalysts that speed up
a specific active site depending chemical reactions
on it's shape
2) When an enzyme locks into the
specific active substrate the
molecule is now known as pH & Temperature
enzyme substrate complex
Two factors that control the rate of
This is the lock & key theory enzymes
Enzymes As the temperature increases...
1) Rate of reaction increases
2) Chances of collision increases
Optimum temperature ­ the 3) Energy levels increases
temperature at which enzymes
work best As the pH increases...
1) Rate of reaction increases
2) Chances of collision increases
3) Energy levels increases
After this temperature the
rate of reaction falls as the However, once it reaches the
enzyme denatures due to optimum temperature the rate
bonds breaking Denatured ­ Shape of
enzyme alters but enzyme of reaction decreases / falls
isn't completely destroyed because enzyme has denatured…read more

Slide 3

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Word equation: Glucose is made. It is important for
Carbon Dioxide + Water Glucose + Oxygen three reasons ...
1) Stored into starch molecules
Balanced Symbol Equation: Happens in all 2) Needed to make other chemical
CO2 + H2O C6H12O6 + O2 green plants reactions
3) Used for releasing energy into
Limiting Factors ­ Factors that affect rate of
Happens in the chloroplast... photosynthesis
1) A green pigment in the chloroplast known The thee key limiting factors are...
as chlorophyll absorbs sunlight
1) Temperature
- During winter and night temperatures are
2) This gives energy for photosynthesis to
much lower making the rate much slower
2) Light Intensity
3) Water molecule is broken down into
- During winter and night especially, there is
Hydrogen and Oxygen atoms. Hydrogen less light present, slowing down the rate
combines with Carbon Dioxide to form
Glucose and Oxygen is released as a waste 3) Concentration of CO2
product - Amount of concentration in air can affect
rate…read more

Slide 4

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Osmosis ­ Diffusions of water molecules from a Plants Wilt :
low concentration to a high concentration
through partially permeable membrane Because ....
-Have little water
Diffusion ­ Movement of particles from a low - So water molecules diffuse from inside cell
concentration to a high concentration (high concentration) to outside cell (low
-Cell membrane shrinks away from the cell wall
Plants Stand Straight:
Osmosis & Because ....
-Have lots enough water
- So water molecules diffuse from outside
Diffusion cell wall (high concentration) to outside cell
(low concentration)
-Cell membrane shrinks away from the cell
Why is glucose stored as starch ?
Plants :
Glucose is soluble and has a high osmotic
potential CO2 diffusion :
-There is high concentration of CO2 molecules in
the air but a low concentration in the leaves
Starch is insoluble and has a low osmotic -CO2 diffuses from the air to the plant via the
potential stomata
-Stomata has air holes which allow gas and
Therefore the rate of reaction would be water to pass freely
more effective…read more

Slide 5

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Aerobic Respiration:
After running athletes tend to
breathe heavily because...
Word Equation:
Glucose + Oxygen Water + Carbon Dioxide + Energy
-They are getting rid of Carbon Dioxide
-Inhaling necessary oxygen to stop lactic
Symbol Equation: acid building up
C6H12O6 + O2 CO2 + H2O
Aerobic & Anaerobic
Anaerobic Respiration: Respiration
Word Equation:
Glucose Lactic Acid + Energy
Aerobic Anaerobic
-Produces water -Water is not a product
Word Equation:
-Uses more energy -Uses less energy
Glucose Ethanol + Carbon Dioxide+ Energy
-Enough oxygen is present -Limited oxygen / no
-Lasts for a longer time
-Lasts for a shorter time…read more

Slide 6

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-They are minerals absorbed by the
-Soluble (dissolve in water)
-They are used to make long chain of
-Root hair cells have large surface amino acids, known as proteins
area to absorb nitrates -Used to make water DNA
-High concentration of nitrates in root
hair cells but low concentration in
plant cell; nitrates want to diffuse to
the root hair cell
-This happens by ACTIVE TRANSPORT
1) Nitrates want to diffuse from low
concentration to high concentration but
they can't due to cell membrane blocking it
2) They enter carrier protein
3) Using energy (released from ATP) carrier
protein rotates to high concentration
4) Nitrate is released, carrier protein turns
back to original shape
Process starts again…read more

Slide 7

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