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Explain the effects of environmental factors on the rate of photosynthesis.
In HKDSE Biology examination, students are required to draw the graph to indicate the effect of light intensity, carbon dioxide concentration and temperature ❗️ ❕
Light intensity ☀️
- The increase of light intensity leads to an increase in photosynthesis rate.
- The rate of photochemical reaction will be enhanced due to the increase of light source.
- More ATP and NADPH will be generated from the photochemical reaction for the use in Calvin cycle.
- 🔸The rate of photosynthesis becomes constant due to the limitation of other factors.
- 🔸The rate of photosynthesis will decline at a very high temperature due to the damage of chlorophyll.
Carbon dioxide concentration 💨
- The increase in carbon dioxide concentration leads to an increase in photosynthesis rate.
- The rate of Calvin cycle will be enhanced due to the increase of carbon dioxide source
- More ADP and NADP+ will be generated from Calvin cycle and use in photochemical reaction.
- 🔸The rate of photosynthesis becomes constant due to the limitation of other factors.
Temperature 🌡
- Photosynthesis is catalysed by the enzyme 🔹rubisco
- The rate of photosynthesis increase when temperature increase.
- The rate of photosynthesis is the maximin in optimal temperature.
- The rate of photosynthesis decline when the temperature is higher than the optimal temperature as enzyme denatured.
That's the end of this topic 👏🏻
References
- Smith, E. L. (1938). Limiting Factors In Photosynthesis: Light And Carbon Dioxide. The Journal of General Physiology, 22(1), 21–35. https://doi.org/10.1085/jgp.22.1.21