Why Is Photosynthesis Important for All Organisms?
- Plants, algae and bacteria transform light energy into chemical energy that is useful to all living organisms. This process is referred to as primary production and those photosynthetic organisms are called primary producers. They form the base of the food chain.
- Plants, algae and bacteria use photosynthesis as a direct energy source. They convert carbon dioxide into carbohydrates for use as an energy source. The energy is used towards the growth and reproduction of the organism. Energy not used for growth or reproduction is lost through plant respiration.
- According to the biophysicist Alfred Lotka's principles of thermodynamics, the energy retained by a primary producer is transferred to the herbivore that consumes it. Similarly, when a carnivore consumes an herbivore the energy of the herbivore, to which the primary producer contributed, is transferred to the carnivore. This process of energy transfer is called the food chain and describes the transfer of energy through an ecosystem. Because energy begins with primary producers, all organisms in an ecosystem indirectly rely on photosynthesis.
- In addition to providing energy in the form of carbohydrates, photosynthesis exports oxygen as a byproduct. Animals and other organisms use the oxygen for respiration.
- Chemoautotrophs are organisms that produce organic compounds from the energy obtained through oxidation of inorganic compounds rather than organic, as in photoautotrophs like plants. They live in rocks and near hydrothermal vents in deep ocean ecosystems. They are the only organisms that do not rely on photosynthesis for energy. Chemoautotrophs produce energy from the reaction of hydrogen sulfide from the hydrothermal vents and oxygen from seawater. Organisms in the community around these vents consume the chemoautotrophs, which are most often bacteria, and begin the transferring of energy, making the bacteria a primary producer.
