Photorespiration Facts for Kids

Photorespiration is a special process that happens in plants. It's a bit like a mix-up during photosynthesis, which is how plants make their food using sunlight. Instead of taking in carbon dioxide, plants sometimes accidentally take in oxygen. This can make it harder for them to grow and make food efficiently.

What is Photorespiration?
Images for kids
See also

What is Photorespiration?

Photorespiration is a natural process that occurs in the cells of plants. It's part of their metabolism, which means all the chemical reactions that keep a plant alive. This process happens when a plant's main food-making enzyme, called RuBisCO, adds oxygen to a sugar molecule instead of carbon dioxide.

How Does It Happen?

Plants use an important enzyme called RuBisCO to capture carbon dioxide from the air. This carbon dioxide is then used to build sugars, which are the plant's food. But sometimes, especially when there's a lot of oxygen around and not much carbon dioxide, RuBisCO makes a mistake. It grabs an oxygen molecule instead of carbon dioxide. This starts the photorespiration process.

Why Does It Happen?

Photorespiration often happens when plants are under stress. For example, if the weather is very hot and dry, plants might close their stomata. Stomata are tiny pores on their leaves that let carbon dioxide in and oxygen out. They close to save water, but this also means less carbon dioxide can enter the plant. When carbon dioxide levels inside the plant drop, RuBisCO is more likely to pick up oxygen instead. Photorespiration also tends to increase when temperatures get higher.

What Does It Do to Plants?

When photorespiration occurs, it makes photosynthesis less efficient. This means the plant can't make as much sugar (food) as it normally would. Unlike regular photosynthesis, photorespiration does not produce ATP, which is the energy currency of the cell. It also causes the plant to lose some carbon and nitrogen, which are important nutrients. Because of this, photorespiration can slow down a plant's growth.

How Do Plants Deal With It?

Some plants have special ways to reduce photorespiration. For example, plants like maize (corn) use a different pathway called the C4 pathway. This pathway helps them keep carbon dioxide levels high around the RuBisCO enzyme, even when their stomata are partly closed. Other plants, like cacti, use a pathway called CAM. They open their stomata at night to collect carbon dioxide and store it, then use it during the day when their stomata are closed. These adaptations help them grow better in hot, dry places.