Photosynthesis Introduction
Year 8 ๐ฌ Cell Biology & Biochemistry The process of photosynthesis, chloroplasts, and limiting factors.
๐ฟ Photosynthesis Overview
Photosynthesis converts light energy into chemical energy stored as glucose. It is the entry point of energy into most food chains.
Word equation
carbon dioxide + water โ glucose + oxygenSymbol equation
$$6CO_2 + 6H_2O \xrightarrow{\text{light energy}} C_6H_{12}O_6 + 6O_2$$- Occurs in chloroplasts (contain chlorophyll)
- Chlorophyll absorbs red and blue light; reflects green
- Glucose can be used for respiration, storage (starch, oils), or building (cellulose, proteins)
๐ Limiting Factors
The rate of photosynthesis is limited by the factor in shortest supply.
- Light intensity โ increasing light increases rate; at high light, COโ or temperature becomes limiting
- COโ concentration โ increasing COโ increases rate; usually only 0.04% in atmosphere
- Temperature โ higher temperature increases rate (enzymes work faster); above ~40ยฐC, enzymes denature โ rate falls sharply
Compensation point: The light intensity at which the rate of photosynthesis exactly equals the rate of respiration โ no net gas exchange.
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