Primary Science


Pee Science: Why is our pee yellow?

A Story of Red Blood Cell Heroes – A Sneak-Peek into Pee Science!

Hey, awesome young explorers! Today, we are going on a super cool journey inside our bodies to discover why our pee is yellow. And guess what? It has to do with our red blood cell heroes!

Meet the Red Blood Cell Heroes.


Our body is like a big city, and in this city, there are millions of tiny heroes called red blood cells. They are like little red cars, zooming around your body highways, delivering oxygen to all the various parts. They are super important for keeping us healthy and energetic!

The Retirement of Red Blood Cell Heroes

Just like people, red blood cells can’t work forever. After about 120 days (which is like working for four whole months without a break!), they retire. Imagine them hanging up their little superhero capes and taking a well-deserved rest.

What Happens After They Retire?


When these red blood cell heroes retire, your body starts to break them down. This process creates a yellow substance called bilirubin. It’s kind of like when you make lemonade, you get that lovely yellow colour!

The Liver’s Special Role

Next, the bilirubin goes on a trip to a place called the liver. Think of the liver as a recycling factory. It takes the bilirubin and mixes it with other stuff to make it ready to leave the body. This mix is what gives your pee that yellow colour!

PEE FACTS – The Science behind it

Yellow Pee: A Sign of Hard Work!

So, when you go to the bathroom and see that your urine is yellow in colour, it’s a sign that your body’s red blood cell heroes did their job well and are now on their way out after their retirement party.


Red Blood Cell Heroes: They carry oxygen and work hard for about 120 days.

Bilirubin, the Yellow Hero: Created when red blood cells retire, it gives your pee its yellow colour.

The Liver, the Recycling Factory: It processes the bilirubin and helps your body get rid of it.

Pee Colour: Changes based on how much water you drink. More water means lighter yellow pee!

REVEALED: The Science behind the Yellow Pee Mystery

And that’s the story of why your pee is yellow! It’s all thanks to the amazing work of your red blood cell heroes and your super-smart liver. Remember to stay hydrated for light yellow pee and celebrate the excellent job your body does every day!

Keep exploring and learning, my young friends, and always remember to drink plenty of water to help your body healthy, heroes!

Read Also: Solving the 2021 PSLE Science Mosquito Question (Life Cycle)


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