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Light. It’s a big part of 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 how plants make the food they need to live and grow.
The word “photosynthesis” means “putting together with light.” That phrase describes what happens in plants. The food-making cells in plants combine water and carbon dioxide. They do it by using light energy. That light energy may come from the Sun. It can also be from an artificial source. A light bulb may do the job, too. Either way, the plant makes sugar. Plants use this sugar, plus nutrients from soil, to make proteins, vitamins, and other things they—and we—need to live.
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 for 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. Plants and animals make hormones. They control growth and development. Auxins are hormones that affect how plant cells grow. Auxins make the cells on the shady side of a plant grow faster than cells on the sunny side do. That’s how a stem can bend toward light. It’s trying to get as much light as possible to shine on as many food-making cells as possible. This effect is called 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.
