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Ask Dr. Universe Archives

Why are carrots orange? - Caden, 11, N.C.

Dear Caden,

When you picture the carrot section at a grocery store in the United States, you probably imagine rows of orange. But carrots can come in a rainbow of other colors: purple, yellow, red, and more.

And the first carrots weren’t orange at all. They were stark white.

That’s what I learned from Tim Waters, a Vegetable Specialist at Washington State University-Extension. He studies how to grow different kinds of vegetables, and helps others learn how to grow them too.

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Dr. Universe: Do trees still create oxygen and clean the air after their leaves fall off? – Nova, 8, Palouse, Wash.

Dear Nova,

The trees that lose their leaves in fall, such as chestnuts, oaks, aspens, and maples, are called deciduous trees. Once they lose their leaves, most aren’t able to take in carbon dioxide gas from the air or produce any oxygen.

That’s what I found out from my friend Kevin Zobrist, a professor of forestry at Washington State University.

“Don’t fret, though,” Zobrist said. “For they more than make up for it in the summer.”

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Dr. Universe: How do trees help the air? – Ella, 12

Take a big, deep breath. As you inhale and exhale, you can probably feel the air taking up space in your lungs. The air we breathe is made up of a few different things. It includes gases such as nitrogen, oxygen, and carbon dioxide—just to name a few. Animals breathe in oxygen and breathe out carbon dioxide. But in the plant world, it’s the opposite. Trees, plants, and even algae in the ocean, take in carbon dioxide from the air and, using the energy of the sun, transform it into the oxygen we all breathe. Read More ...

Why does meat get brown on the grill? – Christina, Seattle, Wash.

Dear Christina,

You know summer is just around the corner when the smell of barbecue is in the air. It’s a great question you ask and it leads us to the Meats Lab at Washington State University. That’s where I met up with my friend and animal scientist, Jan Busboom.

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Why is yawning contagious? -Grant, 10, Pullman, WA

Dear Grant,

When I got your question, I met up with my friend Hans Van Dongen, a scientist at Washington State University in Spokane. He works in a research lab where they study sleep. As a cat who appreciates naps, it’s one of my favorite places to visit.

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If mollusks have such heavy shells to drag around with them, how have they spread all over the ocean? -Michel W.

Dear Michel,

Mollusks, from land snails and slugs to oysters and mussels in the sea, have a few things in common. They have a head. They have a soft middle part that holds their organs. Then, some have a muscle that’s known as a “foot.”

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