Photosynthesis: Why, where and how…
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Transcript of Photosynthesis: Why, where and how…
Photosynthesis: Why, where and how…
An overview of photosynthesis
Which organisms can photosynthesise?
Which organisms can photosynthesise?
• Green plants, phytoplankton and cyanobacteria
• Phytoplankton and cyanobacteria supply half of all atmospheric oxygen
• ‘Red tides’ are caused by photosynthetic protists
Where does photosynthesis occur in plants?
Photosynthetic pigmentsan introduction…
Photosynthetic pigments
• A pigment is a substance that absorbs light• Plants have pigments in the thylakoids of their
chloroplasts: chlorophylls, carotenoids and• Chlorophyll a is directly involved in
photosynthesis while chlorophyll b is an accessory pigment, since it assists in capturing light energy
• Caratenoids give leaves their red, orange and brown hues during autumn
• Why are leaves green?
Carotenoids and chlorophyll: welcome to autumn…
The ‘where’ of photosynthesis: The Chloroplast
Carbon dioxide is often a limiting factor on the rate of photosynthesis
Measuring the rate of photosynthesis
• P. 77 in textbook• Oxygen production:
‘direct measurement’• Carbon dioxide
measurement: ‘Direct measurement’
• Biomass measurement: ‘indirect measurement’
Your next IA
• ‘Design an experiment which evaluates the effect of ONE limiting factor (temperature, light intensity,
light colour or carbon dioxide concentration’ on the rate of photosynthesis’
• You may want to compare different types of plants in your experiment…
The reactions of photosynthesis