Ask Dr. Universe: How do trees give us air to breathe?

Washington State University

Dr. Universe: How do trees give us air to breathe? – Jamar, 11, Vineland, New Jersey

Dear Jamar,

Our planet is home to all kinds of different plants, and they help make a lot of the oxygen we breathe. To find out how plants make oxygen, I asked my friend Balasaheb Sonawane.

Sonawane is a scientist at Washington State University who researches photosynthesis, or the ways plants use energy from the sun and make oxygen. He said that in a way, plants breathe, too.

“They don’t have a nose or mouth,” Sonawane said. “They have tiny microscopic organs on their leaves called stomata.”

The stomata allow gases to move in and out of a leaf. We breathe oxygen gas, but plants take in carbon dioxide gas using the stomata on their leaves.

Meanwhile, plants also use their leaves to help absorb energy from the sunlight. They also suck up water through their roots.

Water is one key thing plants need to make oxygen. You may remember that atoms are like building blocks. When two or more atoms get together, we get a molecule. For instance, one oxygen atom and two hydrogen atoms make a water molecule.

During photosynthesis, plants can convert sun energy into energy they can use to make sugar from the carbon dioxide molecules. When this happens, water molecules break apart and form oxygen molecules – the air we breathe.

Along with oxygen, plants also let a little water vapor out of their stomata. This is important for humans and other animals because it can be difficult to breathe in dry environments. The moisture and oxygen help our lungs keep working.

There are also living things in the ocean called phytoplankton, and they produce about half of the oxygen in the air. Like plants on land, they use carbon dioxide, sunlight and water as they produce food and oxygen.

Plants and phytoplankton both need carbon dioxide to do their work, but now there is too much carbon dioxide in the atmosphere, and it contributes to climate change.

“Humans generate a huge amount of carbon dioxide as they burn fossil fuels in cars, planes, and industries,” Sonawane said. “Plants are helping us reduce the levels of carbon dioxide, but they cannot do enough to make Earth’s environment happy.”

The good news is there are ways to help reduce the carbon dioxide in the air.

First, humans can try to avoid doing things that release carbon dioxide gas. Instead of taking a car that releases carbon dioxide, you might walk or ride a bike when you can. We can also plant more trees on the planet.

“To make a happy and healthy environment, we need to plant more and more trees,” he said.

Perhaps you and your friends can work with your town or city to help plant new trees in your neighborhood. The next time you see a tree, remember all of the amazing things it does to give us air to breathe.

Sincerely,

Dr. Universe

Ask Dr. Universe is a project from Washington State University. Submit a question at askdruniverse.wsu.edu.