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Light. It’s an ingredient in what may be the most important recipe on the planet. Water and carbon dioxide are other key ingredients. The recipe is for photosynthesis. That’s the process plants use to make the food they need to live and grow.
The word “photosynthesis” means “putting together with light.” That phrase describes what occurs in plants. The food-making cells in plants use light energy to combine water and carbon dioxide. The light energy may come from the Sun. It can also be from an artificial source, such as a light bulb. In either case, the result of the process is sugar. Plants use this sugar, plus nutrients from soil, to make proteins, vitamins, and other substances necessary for life.
This is it in a nutshell: Without light energy there would be no sugar; without sugar there would be no plant life; and without plant life there would be no animals or people.
The Food Chain
Plants depend on light, and people and all other animals—even carnivores—depend on plants, because plants are the first link in the food chain.
A food chain shows how living things are connected by food. Of the many food chains, the one here shows how foxes and plants are linked.
Reaching for the Light
Light is so important to plants, they seem to reach toward it. But how does a plant “know” which way to grow? It may not have eyes to see the light, but a plant does have hormones. These are substances made by plants and animals. They regulate growth and development. Auxins are hormones that affect the growth of plant cells. Auxins make cells on the shady side of a plant grow faster than cells on the sunny side do. That way, a plant’s stem may bend toward light to let as much light as possible reach more food-making cells. This phenomenon is known as phototropism.
How Photo- synthesis Works
Cells in the leaves of green plants contain tiny structures called chloroplasts. Inside each chloroplast is usually a green pigment called chlorophyll. Chlorophyll and other pigments trap light energy. Plants need that energy to carry out photosynthesis.
