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Ask Dr. Universe Food and Health
University Communications Network > Ask Dr. Universe > Food and Health

Why is snot green? – William, 7, United Kingdom

Dear William,

There are lots of unpleasant things about being sick. Leaking slimy green snot is near the top of my yuck list.

I talked about it with my friend Linda Eddy. She’s a nurse for kids. She runs the nursing program on the Vancouver campus of Washington State University.

She told me that snot is normally clear. It turns yellow or green when our bodies fight germs that can make us sick.

Snot is also called mucus. It’s a thin, slippery liquid that covers many of the surfaces inside our bodies. You can find mucus in your nose, mouth and eyes. It … » More …

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How is ice cream made? - Israel, 7

Dear Israel,

It just so happens that July is National Ice Cream Month. To celebrate, I decided to whip up some homemade ice cream. You can try it at home, too.

Put milk, sugar and vanilla into a freezer bag and seal it up tight. Fill another gallon freezer bag with ice and rock salt. Place the liquid mix bag inside the bag of ice and give it a good long shake. Some scientists might call this part "agitating." After five minutes or so, you'll notice the liquid mix in your bag becomes solid. Then you can dig in with a spoon.

After making my own homemade tuna-flavored ice cream, I decided to take a trip to the Washington State University Creamery to see how the professionals make ice cream for Ferdinand's Ice Cream Shoppe.

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Why does milk cure the spicy feeling in your mouth after you eat something spicy but water doesn't? – Eloise, 10, Minnesota

Dear Eloise,

My work as a science cat has introduced me to human foods—like chips and salsa. I love the spicy taste of salsa, but I always keep a saucer of milk handy.

I talked about why milk calms the spicy feeling with my friend Emily Cukier. She’s a chemistry librarian at Washington State University.

She told me that the spicy feeling comes from something called capsaicin. The amount of capsaicin in a pepper determines how hot it is.

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I want to know how snake venom in the antidote makes sense? – Raagini, 10, New York

Dear Raagini,

One of my roommates is a corn snake named Buddy. He’s not venomous. But he’s a very private individual and really likes his space.

Buddy and I talked about your question with my friend Blair Perry. He’s a biologist at Washington State University. He’s an expert on snakes and venom.

Perry told me antivenom doesn’t contain actual snake venom. It’s made with antibodies to snake venom.

Antibodies are proteins. They’re part of your immune system. They travel in your blood to fight germs or dangerous molecules—like those in venom—that could hurt you. Sometimes we get vaccines to boost our antibodies so they’re ready when something harmful shows up.

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How do I make compost without a compost maker? – Miracle, 15, Nigeria

Hi Miracle,

My office is just down the road from the Washington State University composting facility. It processes more than 10,000 pounds of organic waste every month. That’s a lot of compost!

I talked about compost with my friend Jim Kropf. He works for WSU Extension. Extension programs connect universities with local communities. They offer classes and trustworthy, science-based resources that anyone can use online.

Kropf told me that composting is how nature recycles. “In the forest, leaves fall on the ground and come in contact with soil,” he said. “Worms, centipedes, microorganisms and fungi all work on those leaves to break them down into organic matter.”

Making compost is copying nature to make fertilizer for healthier gardens. It’s also a way to help our planet.

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What are microorganisms? –Trystan, 11, North Carolina

Dear Trystan,

One of my favorite things to do is look at pond water with a microscope. I love to see all the teeny tiny critters zooming around in a single drop.

I talked about microorganisms, also called microbes, with my friend Claire Burbick. She’s a microbiologist at Washington State University. She told me the key trait for microbes is size. Microbes are micro—which means extremely small.

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Dr. Universe: Why do we get sleepy when we study? - Sadaf, 12, Pakistan

Dear Sadaf,

Like many good students, you’ve probably noticed that when you study, especially late in the day, you feel sleepy. Scientists don’t know exactly why, but they have a few clues.

The human brain is packed with tens of billions of cells called neurons, which process and store information that helps us observe, understand and make decisions about the world.

My friend Hans Van Dongen, director of the Sleep and Performance Research Center and a professor of medicine at Washington State University, said you might think about neurons as workers in a huge company. Each neuron is an expert in a piece of information, and neurons work together to share what they know and build new connections in the brain.

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Dr. Universe: What’s the purpose of baking soda? What’s the purpose of baking powder? What’s the difference between the two? - Kyle, 9, Florida

When I got your question, I headed straight to my kitchen cabinet. I grabbed some baking soda and baking powder from the shelf and made some observations. Not only did the baking soda and baking powder look similar to one another but both contained an ingredient called sodium bicarbonate. Read More ...

Dr. Universe: How does toothpaste clean your teeth? -Lucy, 10, Pullman, WA

Dear Lucy, If you are anything like me, every day you squeeze a little toothpaste onto your toothbrush and brush your teeth. Toothpaste gets its cleaning power from a few different ingredients. My friend Mark Leid was happy to tell us about how they work. Leid spent part of his career teaching future dentists. He is also dean of the Washington State University College of Pharmacy and Pharmaceutical Sciences. First, he told me the outer covering of a tooth is called enamel. It’s the hardest tissue in the whole human body—even harder than bone—and it helps with things like chewing your food. Read More ...

Dear Dr. Universe: Why do some cheeses stink? – Cody, 11

When you take a whiff of stinky cheese, that smell is coming from one of its very important ingredients: microorganisms. Microorganisms are so small, you’d need a microscope to see them, but sometimes they give off a big stink. To find out more about stinky cheese, I talked to my friend Minto Michael. Michael is a professor of dairy science at Washington State University and told me microorganisms do a few different jobs to help make cheese. Read More ...

Dr. Universe: Why do trees have sap? -Aliyah, 8, Kirkland, WA  

Just as blood moves important stuff around the human body, sugary sap moves important things around a tree. My friend Nadia Valverdi told me all about it. She’s a researcher at Washington State University who studies how apple and cherry trees survive in different environments. When we eat food, like a delicious apple or a handful of cherries, we get important nutrients. Read More ...

Dr. Universe: How do you make cider? -Julianna, 7

We can make cider with juice from apples. There are many different kinds of apples and a few different ways to squeeze out the juice. My friend Bri Valliere told me all about it. She’s a food scientist at Washington State University who knows a lot about cider. The first step is to pick out the apples. Honeycrisp apples will make a sweet cider. Granny Smiths are more acidic and will make a tart cider. “We could make a single batch of one kind, or we could mix different kinds of apples together and see how it turns out,” she said. “No matter what, it’s going to taste good.” Read More ...

Dr. Universe: With the coronavirus why is it effective to wear a mask? How does it make life safer? - Marin, age 12, in Ohio

Dear Marin, Whenever I go out and about, I make sure to wear my face mask. Like you, I wanted to find out exactly how they work. First, I talked to Marian Wilson, an assistant professor and nurse at Washington State University who is curious about how face masks protect people. “When we talk, sneeze, sing, or laugh, we spread droplets into the air all the time,” she said. “With the COVID-19 pandemic going on, we know people may have virus in their droplets.” Read More ...

Dr. Universe: Why do we need to eat and drink? -Victoria, 7, MN

Just like a car needs gas to run, food is the body’s fuel. Food gives us energy, or the power to do work. It helps us run, jump, think, and do all kinds of things. That’s what I found out from my friend Alice Ma, a dietician at Washington State University. When you take a bite of food it goes down your throat, or esophagus, and down into your stomach. In the stomach and small intestine, things like bile, acid, and enzymes help digest, or break down your food so your body can absorb the parts it needs. Read More ...

Dr. Universe: Why does soap get bubbly? Samuel, 9, East Peoria, IL

When you wash your hands with soap and water, a few different things happen to make bubbles. Just like you, water and soap are made up of parts called molecules. Water molecules really like to stick together. If you’ve ever jumped in a puddle or a pool, you may have even observed how water splashes in the shape of little drops. As water sticks together, it likes to form spheres. Read More ...

How are vaccines made? - Sibagh, 7, New York City, NY

It might seem strange, but a small piece of something dangerous can protect you against something much more dangerous. This idea has been around for a long time—and it works. To learn more, I talked to Guy Palmer at Washington State University. As a scientist who studies infectious disease, Palmer likes learning about how to protect both human and animal health. Vaccines are one way to accomplish this. Read More ...

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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Why do I like buffalo wings and not broccoli? - Joe, 10, New York City, NY

Dear Joe,

You’re not alone—cats don’t like broccoli much either. As a carnivore, I think a nice, meaty buffalo wing sounds great.

But humans are omnivores, meaning they eat both plants and meat. They’ve developed a taste for all kinds of things growing and living all over the world. So where do individual people’s preferences come from?

To find out, I visited Carolyn Ross, a professor of Food Science at Washington State University. Like you, she is very curious about why people like the foods they like.

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How was popcorn discovered? - Jalen, 12, Benson, N.C.

Dear Jalen,

There’s nothing like popcorn in progress: the snapping kernels, the warm buttery smell, and the knowledge that a delicious snack will be ready in minutes. It gives you some good time to think and wonder: how did humans first start doing this?

To find out where popcorn came from, I visited my friend Erin Thornton, an archaeologist at Washington State University. Archaeologists study how humans lived in the past—including the things they ate.

To learn the story of popcorn, we have to trace the history of maize.

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Dr. Universe: Do babies have ways of communicating? –Jalen, 12, North Carolina

Dear Jalen, Babies can communicate in a few different ways. For the most part, they use their emotions. Humans come into the world crying, but that’s actually a good thing. In a way, babies start communicating from the moment they are born. Of course, it can be hard for their caregivers to know exactly what they mean with all those cries. Read More ...

Dr. Universe: How do bags form under your eyes? –Sophia Ivy, 7, New Providence, NJ

Dear Sophia Ivy, If you’ve ever stayed up late and woke up really early, you may have noticed a little puffiness or swelling under your eyes. When I asked my friend Devon Hansen about the answer to your question, she said that we first have to know a bit about how sleep works. Read More ...

Who created the very first chocolate bar? – Emma, 11, USA

Dear Emma,

For most of human history, people have enjoyed chocolate in a spicy, bitter drink. But when people discovered how to turn chocolate into a solid, it opened up a whole new world of possibilities.

That’s what I found out from my friend Omar Cornejo, a scientist at Washington State University who is very curious about the history and life of the cacao tree. Chocolate comes from the seeds of leathery fruits that grow on the tree.

If we cut open the fruit, we would find about 20 to 60 seeds on the inside. In ancient times, people would grind up the seeds … » More …

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Dr. Universe: Why are there different blood types? - Sarah, Tacoma, Wash.

Dear Sarah,

At this very moment, several quarts of blood are circulating through your body at nearly 4 mph. But as you’ve pointed out, not everyone’s blood is the same.

Your question made me wonder exactly what we mean when we talk about blood types. I decided to ask my friend Amber Fyfe-Johnson, a researcher at Washington State University who studies cardiovascular diseases--diseases of the blood vessels-- in kids.

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What do astronauts eat in space? –Rhemi, 12, St. Louis, Mo.

Dear Rhemi,

Astronauts eat all kinds of different foods up in space. The food is often similar to what we have here on Earth. But in space, there's very little gravity. There’s very limited refrigeration, too. On the International Space Station, the refrigerator is only about half the size of a microwave. That means scientists who prepare and package astronaut food have to do it in ways that take up very little room and don’t need to be kept cold.

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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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Dr. Universe: I have a ginormous question for you. How come non-biodegradables take like a million, billion, zillion years to decay? -Madeline C., age 8

Dear Madeline,

You’re right. It can take a really long time for some things to decay.

If we buried an apple peel in the backyard it might only take a few weeks to break down into the soil. But if we buried a plastic water bottle, it would probably still be there hundreds of years from now.

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Hi, Dr. Universe! When I was eating breakfast today, I came up with this question. Why does crispy rice make a popping sound when I pour milk over it? It makes me curious as a cat! -Allison, 11, Pullman, WA

Dear Allison,

My ears perked right up when I got your question. Like you, I’ve heard the sounds crispy rice cereal makes. But the truth is, I wasn’t entirely sure why it happens. There was only one way to find out.

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What is Dr. Universe's favorite experiment? -Garrett, 8th grade, Eastern Washington

Dear Garrett,

You know, your question reminds me of a couple other science questions from curious readers. Evangeline, age 7, wants to know why her hair is black. Sureya, age 8, wants to know why some people have curly hair.

It just so happens that one of my favorite science projects explores our questions about what makes us unique. It has to do with our DNA, or the blueprint for life.

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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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Dear Dr. Universe, Please answer this question: Do animals dream? What dreams do they get? I humbly request you to answer these questions. BYE! Or should I say MEOWY! -Prahlad R.

Dear Prahlad,

After a quick catnap and a stretch, I went to visit my friend Marcos Frank, a scientist at Washington State University who studies animal sleep.

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Why are ripe fruits sweet and why is it so important?  -Alexa, Schenzhen, China

Dear Alexa,

My friend Kate Evans said the answer really depends on whether you want the perspective of a person, a plant, or even a cat. Evans is a plant scientist at Washington State University in Wenatchee, where she investigates fruit in the Apple Capital of the World.

She explained how long ago, wild apples actually grew in forests. Without farmers around to plant them in orchards, trees had to scatter their own seeds to survive.

For some trees, the key to survival is growing sweet, ripe fruit.

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Will I ever like Brussels sprouts? - Susan 

Dear Susan,

Cats aren’t usually big veggie-eaters. But working with humans means that I get to taste all kinds of new delicacies—like Brussels sprouts.

I talked about food preferences with my friend Carolyn Ross. She’s a chemist and food scientist at Washington State University.

She told me that some people are extra sensitive to how foods taste. They’re called supertasters.

“Supertasters actually have more taste buds,” Ross said. “We’ve found that people who are supertasters are particularly sensitive to bitterness.”

Bitterness really strikes at a supertaster’s fungiform papillae. Those are the mushroom-shaped lumps on your tongue that house your taste buds. Because of … » More …

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