Role Of Water In Photosynthesis

When you feel low on energy and need a snack, you probably just open the refrigerator or rifle through a kitchen drawer. When plants get the urge for an energy bump, their process is a bit more complex and also more direct because they go straight to the source: the sun.

In order to produce energy, plants undergo a process called photosynthesis. The chemical formula for photosynthesis is 6CO₂ + 6H₂O ——> C₆H₁₂O₆ + 6O_2. If you look at the left side of the equation, you see the ingredients that plants require for photosynthesis: six molecules of carbon dioxide (CO₂) and six molecules of water (H₂O).

While plants take in carbon dioxide through tiny pores located on their leaves, stems and flowers, they need specialized structures to gather water and move it up through their stems. Most plants use roots to pull water from the earth. To do this, they rely on long, thin root hairs dispersed through the soil. Since the cytoplasm of the root hair cells has lower water potential than the water in the soil, osmosis pulls the water from the root hairs through the root cortex and into the xylem.

The xylem is a system of tubelike vascular bundles that transports water up the plant's stem and into its leaves. It might be helpful to imagine the xylem as blood vessels stretching through the plant's body. The process of moving water through the plant is called transpiration.

Plants with enough water and carbon dioxide harness the power of photons gathered from sunlight to complete photosynthesis. The six molecules of carbon dioxide and six molecules of water on the left side of the photosynthesis equation break apart and reconfigure into glucose and six molecules of oxygen. The sugar (glucose) can be used for energy immediately or stored for later use while the oxygen releases through the plant's pores as a waste product.

Since humans can't perform photosynthesis, they rely on the energy produced and stored by plants. This means that when you make a snack in your kitchen, a plant was responsible for producing all the energy that you consume. Even if the snack is meat-based, plants were the initial energy source for the animal. It's hard to imagine that the energy that sustains your life and allows you to move started out as carbon dioxide, water and sunlight – but it's true!