1. Capturing Sunlight:
- Plants contain a green pigment called chlorophyll within organelles called chloroplasts.
- Chlorophyll absorbs light energy, primarily in the red and blue wavelengths, reflecting green light (which is why plants appear green).
2. Splitting Water:
- The absorbed light energy is used to split water molecules (H₂O) into hydrogen ions (H⁺), electrons (e⁻), and oxygen gas (O₂).
3. Creating Energy Carriers:
- The released electrons are used to create two energy-carrying molecules:
- ATP (adenosine triphosphate): This molecule stores energy in its chemical bonds.
- NADPH (nicotinamide adenine dinucleotide phosphate): This molecule carries electrons.
4. Carbon Dioxide Fixation:
- The plant takes in carbon dioxide (CO₂) from the atmosphere.
- Using the energy from ATP and the electrons from NADPH, the plant converts CO₂ into glucose (C₆H₁₂O₆), a simple sugar. This process is called the Calvin Cycle.
5. Energy Storage:
- The glucose produced is a source of chemical energy for the plant.
- It can be used immediately for growth and other processes, or it can be stored as starch for later use.
Overall Equation:
6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂
Key Points:
- Photosynthesis is essential for life on Earth, as it provides the oxygen we breathe and is the foundation of most food chains.
- Plants use sunlight, water, and carbon dioxide to create glucose and oxygen.
- Chlorophyll plays a crucial role in capturing light energy.
- The energy stored in glucose is used by plants for growth, reproduction, and other vital processes.
