- Photosynthesis is a process that forms carbohydrates, especially sugars, from carbon dioxide and a source of hydrogen (e.g., water) in the chlorophyll-containing tissues of plants exposed to light. All living organisms containing green photosynthetic pigments called chlorophyll, including autotrophic plants, algae, and some species of bacteria, can synthesize compounds with the aid of radiant energy. Photosynthesis is a direct or indirect source of energy for nearly all living things on Earth. Furthermore, photosynthesis is the core of the oxygen cycle, thereby maintaining the normal oxygen level in the atmosphere. The rate of photosynthesis is contingent upon several factors, such as light intensity, temperature, and carbon dioxide concentration.
- Except for some chemosynthetic bacteria, all green plants require radiant energy during photosynthesis. When light falls on leaves, about 50 percent of the incident light is reflected. A much lower percentage is transmitted, and the rest is absorbed by the leaves. These percentages depend on the texture, thickness, and surface characteristics of leaves. The rate of photosynthesis increases with the gradual increase of light intensity, where other factors (for instance, temperature and the concentration of carbon dioxide) exist in insufficient amounts.
Concentration of Carbon Dioxide
- Under suitable conditions of light and temperature, the rate of photosynthesis is directly proportional to the concentration of carbon dioxide, but the rate of photosynthesis decreases at higher concentrations of carbon dioxide.
- In general, an increase in temperature up to a certain limit enhances the rate of photosynthesis when other factors are not limiting it. The rate of photosynthesis increases within a temperature range between 6 degrees Celsius and 37 degrees Celsius. Above 37 degrees Celsius and below 0 degrees Celsius, the rate decreases because of partial inactivation of enzymes.
- The rate of entry of carbon dioxide and the penetration of incident light depend on the position, size, and distribution of stomata, the distribution of intercellular spaces, and the relative proportion and distribution of palisade and spongy parenchyma. So the leaf anatomy has a pronounced effect on the rate of photosynthesis.
- As protoplasm is an essential constituent of all living cells, all biological processes will stop in the absence of it. During photosynthesis several enzymes are necessary at different steps. These enzymes are present in the protoplasm, which means it enhances the rate of photosynthesis.
- It is a well-known fact that photosynthesis is impossible in the absence of chlorophyll. So the rate of photosynthesis will increase in proportion to the chlorophyll content of a leaf.