1. REVISION: RESPIRATION & PHOTOSYNTHESIS
Topic 3
IB Biology
Miss Werba

2. CELL RESPIRATION

3. 3.7.1
RESPIRATION
Cellular respiration: The controlled release of energy in the form of ATP from organic compounds in cells
Respiration occurs in every living cell.
Gets usable energy from nutrients:
ATP = adenosine triphosphate
ATP is able to diffuse to any part of the cell and release energy
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4. RESPIRATION Cellular respiration can be: aerobic
3.7.1
RESPIRATION
Cellular respiration can be:
aerobic
respiration with oxygen
anaerobic
respiration without oxygen
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5. GLYCOLYSIS First stage of respiration – both aerobic and anaerobic
3.7.2
GLYCOLYSIS
First stage of respiration – both aerobic and anaerobic
Occurs in cell cytoplasm
Does not use oxygen
Substrate(s)
Product(s)
Energy
glucose
2x pyruvate
2 ATP used
4 ATP produced
= 2 ATP overall gained
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6. ANAEROBIC RESPIRATION
3.7.3
ANAEROBIC RESPIRATION
Occurs in absence of oxygen
Also called fermentation
No further ATP is produced
There are generally two types of fermentation:
Lactate fermentation - animals
Alcohol fermentation - plants & yeasts
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7. ANAEROBIC RESPIRATION ~ LACTATE FERMENTATION ~
3.7.3
ANAEROBIC RESPIRATION ~ LACTATE FERMENTATION ~
Animals only
Waste product is lactic acid (lactate)
Lactate can build up in muscles after exercise and cause soreness.
Substrate(s)
Product(s)
Energy
2x pyruvate
2x lactate
no ATP
produced
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8. ANAEROBIC RESPIRATION ~ ALCOHOL FERMENTATION ~
3.7.3
ANAEROBIC RESPIRATION ~ ALCOHOL FERMENTATION ~
Plants and yeast
Products are ethanol and carbon dioxide
This reaction is the basis of the brewing and baking industries.
Substrate(s)
Product(s)
Energy
2x pyruvate
2x ethanol
+ 2x carbon dioxide
no ATP
produced
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9. AEROBIC RESPIRATION Occurs in presence of oxygen (6 molecules)
3.7.4
AEROBIC RESPIRATION
Occurs in presence of oxygen (6 molecules)
Pyruvate from glycolysis absorbed by mitochondria
Substrate(s)
Product(s)
Energy
2x pyruvate
6x carbon dioxide
+ 6x water
+ heat
36 ATP
produced
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10. AEROBIC RESPIRATION C6H12O6 + 6O2  6CO2 + 6H2O
Glucose (6C) diffuses into the cytoplasm and is broken down into two pyruvate (3C), producing 2 ATP.
If oxygen is present, it is transported to the cell on haemoglobin. Pyruvate is then broken down in the mitochondria to carbon dioxide and water, producing a further 36 ATP.
If no oxygen is present, anaerobic respiration will occur, producing lactic acid (lactate) and no further yield of ATP.
Anaerobic respiration can happen at the same time as aerobic respiration.
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11. RESPIRATION
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12. PHOTOSYNTHESIS

13. PHOTOSYNTHESIS Light energy converted to chemical energy
3.8.1
PHOTOSYNTHESIS
Light energy converted to chemical energy
Process used by plants and other organisms (eg. photosynthetic algae)
Occurs in chloroplasts
Complex process
Produces organic compounds from inorganic substrates
Produces oxygen as a byproduct
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14. LIGHT ENERGY Sunlight is called white light.
3.8.2
LIGHT ENERGY
Sunlight is called white light.
Composed of visible light spectrum = ROYGBIV
Different colours have different wavelengths
Short waves = have most energy = ‘blues’
Long waves = have least energy = ‘reds’
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15. CHLOROPHYLL Photosynthetic pigment
3.8.3
3.8.4
CHLOROPHYLL
Photosynthetic pigment
Some colours or wavelengths are absorbed better than others
RED and BLUE are absorbed better than GREEN
Green light is reflected (making plants appear green).
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16. 3.8.5
LIGHT DEPENDENT STAGE
Some energy absorbed is used for the photolysis of water:
water molecules split into H+ ions, O2 and electrons
Some energy absorbed is used to make ATP
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17. 3.8.5
LIGHT DEPENDENT STAGE
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18. LIGHT INDEPENDENT STAGE
3.8.6
LIGHT INDEPENDENT STAGE
Carbon fixation occurs
The H+ and the ATP made in the Light Dependent Stage are used to “fix” the carbon in gaseous carbon dioxide - forming solid glucose
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19. LIGHT INDEPENDENT STAGE
3.8.6
LIGHT INDEPENDENT STAGE
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20. RATE OF PHOTOSYNTHESIS
3.8.7
RATE OF PHOTOSYNTHESIS
Can be measured by:
depletion of substrate (carbon dioxide)
accumulation of products (oxygen or glucose)
increase in biomass
Uptake of carbon dioxide measured by analysing pH of water using pH indicators:
pH of water will rise as CO2 is absorbed
Production of oxygen measured by volume of oxygen bubbles produced:
Aquatic plants release bubbles of oxygen which can be collected in a gas jar
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21. FACTORS AFFECTING RATE OF PHOTOSYNTHESIS
3.8.8
FACTORS AFFECTING RATE OF PHOTOSYNTHESIS
Requirements for photosynthesis:
Presence of chlorophyll
Presence of light
Presence of carbon dioxide
Presence of water
Suitable temperature
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22. FACTORS AFFECTING RATE OF PHOTOSYNTHESIS
3.8.8
FACTORS AFFECTING RATE OF PHOTOSYNTHESIS
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23. FACTORS AFFECTING RATE OF PHOTOSYNTHESIS
3.8.8
FACTORS AFFECTING RATE OF PHOTOSYNTHESIS
Temperature:
Optimal temp
Increases in temp increase kinetic energy of reactants
Too high  enzymes/proteins denatured
Carbon dioxide concentration:
Increases in CO2 concentration increases rate of photosynthesis
Rate plateaus at maximum efficiency
Light intensity:
Increases in light intensity increases rate of photosynthesis
Rate plateaus as chlorophyll is damaged at high light intensities
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