Please explain photosynthesis.
http://www.biology4kids.com/files/plants_photosynthesis.html
Photosynthesis is the process by which green plants, algae, and some bacteria convert sunlight, carbon dioxide, and water into glucose (a type of sugar) and oxygen. This process is crucial for life on Earth as it provides the primary source of energy for most organisms.
To understand photosynthesis, let's break it down into simpler steps:
1. Sunlight absorption: Green plants have pigment molecules called chlorophyll that can capture light energy from the sun. This energy is essential for the photosynthesis process to begin.
2. Carbon dioxide uptake: Plants take in carbon dioxide from the atmosphere through tiny openings called stomata present on their leaves or stems.
3. Water absorption: Roots of plants absorb water from the soil and transport it to the leaves through tubes called xylem.
4. Light-dependent reactions: In this step, light energy is used to split water molecules into hydrogen and oxygen. This process takes place in the chloroplasts, which are the main sites of photosynthesis in plant cells.
5. Production of ATP and NADPH: The energy from sunlight is used to generate adenosine triphosphate (ATP) and reduce nicotinamide adenine dinucleotide phosphate (NADPH). These energy carriers play a critical role in the next step.
6. Calvin cycle (or light-independent reactions): This is where the actual synthesis of glucose occurs. Carbon dioxide from the atmosphere, along with the ATP and NADPH produced in the previous steps, are used to convert simple molecules into glucose. This process takes place in the stroma, which is the fluid inside the chloroplasts.
7. Oxygen release: In the light-dependent reactions, oxygen gas (O2) is produced as a byproduct. It is released into the atmosphere through the stomata.
Overall, photosynthesis is a complex process that requires sunlight, carbon dioxide, and water to produce glucose and release oxygen. It provides both energy and oxygen for life on Earth, while also regulating the carbon dioxide levels in the atmosphere.