Definition of Photosynthesis
Photosynthesis is the biochemical process by which green plants, algae, and some bacteria convert light energy from the sun into chemical energy stored in glucose. In environmental science, it is essential for understanding energy flow in ecosystems, as it uses carbon dioxide (CO2) from the atmosphere and water (H2O) to produce glucose (C6H12O6) and oxygen (O2), represented by the equation: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2.
Key Components and Stages
Photosynthesis occurs in two main stages: the light-dependent reactions, which take place in the thylakoid membranes of chloroplasts and generate ATP and NADPH while releasing oxygen, and the light-independent reactions (Calvin cycle), which occur in the stroma and use ATP and NADPH to fix CO2 into glucose. Chlorophyll, the green pigment in chloroplasts, absorbs sunlight, primarily blue and red wavelengths, making plants appear green.
Practical Example in Ecosystems
In a forest ecosystem, trees like oaks perform photosynthesis during daylight hours, absorbing CO2 from the air and releasing O2, which supports animal respiration and maintains atmospheric balance. For instance, a single mature tree can produce enough oxygen in a season to sustain two humans, illustrating how photosynthesis drives primary production in food webs.
Importance in Environmental Science
Photosynthesis is vital in environmental science for regulating the Earth's climate through the carbon cycle, where it sequesters CO2, mitigating global warming. It forms the base of most food chains, influences biodiversity, and affects water cycles via transpiration. Disruptions, such as deforestation, reduce photosynthetic capacity, leading to increased CO2 levels and ecosystem imbalance.