What is photosynthesis?

Have you ever wondered how a tiny seed grows into a gigantic, towering oak tree without ever taking a single bite of food? It sounds like pure magic, but it is actually incredible science! Join Mira and Finn on Science is Not Boring as they uncover the mind-blowing secret of plants: photosynthesis! Discover how leaves act like tiny solar panels, using a special green chemical called chlorophyll to catch sunlight and mix it with water and air to make their very own sugary candy! Listen in to hear about wild history experiments, like a scientist who baked 200 pounds of dirt to prove plants don't eat soil, and another who watched underwater leaves blow fizzy oxygen bubbles! Did you know that invisible ocean plants called phytoplankton make most of the air we breathe? Or that giant, heavy tree trunks are literally built out of thin air and sunshine?! From bubbling mint leaves to the real reason beautiful autumn leaves change color, get ready to find out why trees, grass, and seaweed are the quiet superheroes keeping every animal on Earth alive! Next time you take a deep breath, you'll know exactly who to thank!

Transcript

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Welcome to Science Is Not Boring by Kidopoly.com. I'm Mira! And I'm Finn! Every single time you take a deep breath, you can thank a quiet, incredible factory that doesn't even have a mouth. Wait, a factory? What kind of factory makes air? A plant! Today we are exploring the mind-blowing trick called photosynthesis. Photosynthesis? That is a massive word. Does it mean they take pictures of things? Not quite. Plants never go grocery shopping, and they definitely don't hunt for their dinner. Yet, a large oak tree can grow as tall as a ten-story building, weighing over 20,000 pounds, and it never chews a single bite of food. That is like two whole school buses stacked together. Where do they get all that food if they don't eat? Do they sneak out at night? That is the craziest part, Finn. They make their own sugary food entirely out of thin air, water, and sunlight. It is a spectacular chemical reaction happening all around us. Hold on, they eat sunbeams and air? That sounds like pure magic. It is science. Sunlight travels 93 million miles through space just to strike a leaf and power this whole process. And without it, every animal on Earth would completely run out of oxygen. Run out of air? Okay, you better explain this to me right now. Let's break it down. Inside plant leaves, there is a special green chemical called chlorophyll. Chlorophyll? Is that why almost all leaves are green? Exactly! Chlorophyll is the star of the show. It acts like a tiny microscopic solar panel. It captures the bright light energy from the sun and stores it inside the plant cells, in tiny little compartments called chloroplasts. So the plant just traps sunlight inside its leaves? That is brilliant! Yes! Then it takes that trapped sunlight and mixes it with water that is sucked all the way up from its roots in the ground. Finally, it adds a gas called carbon dioxide that it breathes in through microscopic mouths on the bottom of its leaves. Carbon dioxide? Isn't that the invisible stuff we breathe out when we exhale? You got it! Plants literally breathe in what we breathe out. They mash the water, carbon dioxide gas, and sunlight together in those little green factories to create glucose, which is a sweet sugar they use for energy to grow. Plants are basically making their own candy using the sun. Sort of. But for hundreds of years, scientists had absolutely no idea this invisible chemistry was happening. People used to think plants grew by eating dirt. Ew, eating dirt? Why would they think they were munching on soil? Because a plant's roots are buried deep in the dirt. But back in the 1600s, a curious scientist named Jan van Helmont decided to test this theory. Ooh, I love a good experiment. What did he do to prove them wrong? Jan van Helmont was a scientist who demanded actual proof. So he got a very large pot and carefully dried out exactly 200 pounds of soil in a hot oven to remove every single drop of water. 200 pounds of baked dirt. That is way heavier than me. Yep, he put that bone-dry soil in the pot and planted a tiny willow tree suppling that weighed exactly five pounds. He weighed everything super carefully with a heavy scale. Okay, five pounds of tree, 200 pounds of dirt. Then what did he do? He watered the tree with pure rainwater for five whole years. He even covered the top of the pot with a special iron plate with holes in it, so no extra dust or dirt could blow in from the wind. Five years is such a long time to wait for a science experiment. What happened to the little tree? The tiny sapling grew into a massive, healthy tree. When he finally pulled it out of the pot and weighed the tree, it weighed 169 pounds and three ounces. Whoa! It gained over 164 pounds of solid wood. I bet all the dirt in the pot was completely gone. That is the wildest part! He took all the soil left in the pot, dried it in the oven again, and weighed it. The dirt still weighed 200 pounds, minus just two tiny ounces. Wait, hold on. The tree gained 164 pounds, but the dirt only lost two ounces. Where on earth did the rest of the heavy tree come from? Van Helmont concluded that the entire heavy tree was made out of the water he poured in over the five years. It was a huge breakthrough because he proved plants don't eat dirt. But was he right? Can water just magically turn into solid wood? He was only partially right. The water helped, but he didn't know anything about the invisible gases floating in the air. The real answer came much later, in 1771, from a famous English scientist named Joseph Priestley. He was doing wild experiments with different kinds of air. Did he bake more dirt in an oven? No, he used a glass spell jar, a burning candle, a live mouse, and a sprig of green mint. He was trying to figure out what happens when air gets, quote unquote, injured. A mouse trapped in a jar? Oh no, is the little mouse okay? The mouse was completely fine. Priestley found that a candle burning or a mouse breathing in a sealed jar would quickly use up all the good air. But when he put a living mint plant inside the jar with them, the plant miraculously restored the air. The plant fixed the air. But how does a simple mint leaf do that? As plants make their sugary food, they release fresh oxygen as a waste product. It is like they are exhaling life-saving air. Then, in 1779, a brilliant Dutch scientist named Jan Ingenhaus took it even further. What did he do? Did he use a mouse too? No mice. He put leafy green plants completely underwater in clear glass containers. When he put the underwater plants in bright, direct sunlight, he saw hundreds of tiny, shimmering bubbles forming right on the green leaves. Oh wow! Just like the fizzy bubbles in a glass of soda. Exactly. And when he moved the glass containers into a dark closet away from the sun, the bubbles completely stopped forming. So they only blow bubbles when the sun is shining. What were the bubbles made of? Pure oxygen. Ingenhaus proved that plants use sunlight to make food and breathe out oxygen. And the heavy solid wood of a huge tree is actually built from carbon dioxide gas sucked straight out of the air. Wait, so giant trees are literally made of thin air and sunshine? That is the coolest thing I have ever heard in my entire life. It really is. And this silent green magic is keeping every single animal on our planet alive. Right now, a single large oak tree can pull up over 100 gallons of water in a single day, sending it hundreds of feet into the air through tiny tubes in its trunk. 100 gallons? That is enough to fill a couple of big bathtubs every single day. Yes, and over a single summer season, one big leafy tree pumps out as much pure oxygen as 10 people breathe in an entire year. Without them, we wouldn't survive. But what about the ocean? There are no oak trees growing down there. Actually, there are tiny floating microscopic plants called phytoplankton. They live near the surface of the ocean, soaking up the sun. They are so small, you need a powerful microscope to see even one of them. Tiny invisible ocean plants doing photosynthesis? Yes, and there are literally trillions and trillions of them drifting in the ocean currents. Together, they produce 50 to 80% of all the oxygen on Earth. That means every second breath you take comes directly from the ocean. But wait, what happens in autumn when leaves turn red and yellow? Do they stop working? Great question. As winter approaches and the days get shorter, there is much less sunlight. The trees know it's time to rest, so they stop making that green chlorophyll. So the green colour just disappears. Exactly. The green fades away. And when it does, we can finally see the other colourful chemicals that were hiding inside the leaf all summer long. Like the beautiful yellows, oranges, and reds. So beautiful autumn leaves are just plants packing up their green factories for a winter vacation. Alright Finn, time for the quiz. Are you ready? Okay, my brain is full of sunshine and facts. Let's do this. First question. What is the name of the special green chemical that catches sunlight inside plant leaves? Next one. This is a tricky numbers question. In Jan van Helmont's experiment, how much weight did the dirt lose after five whole years? Question 3. What did the scientist Jan Ingenhaus see forming on the leaves of underwater plants when he put them in the sun? Alright, here's number four. What invisible gas from the air actually makes up the heavy solid wood of a tree? Last question. What are the tiny microscopic ocean plants called that make over half of our planet's oxygen? Great job! Let's go through the answers. The answer to question one is chlorophyll. For question two, the baked soil only lost about two tiny ounces. Number three, the answer is he saw tiny shimmering bubbles of oxygen. Question four. Carbon dioxide gas is what builds the tree. And the final answer is phytoplankton! Wow, we land so much today. I will honestly never look at a piece of wood or a simple green leaf the same way again. Me neither. It is literally just sunshine and air mashed together. I'm going to go say a huge thank you to the big oak tree in my yard right now. Before you do that, we have a quick favour to ask our awesome listeners. If you loved learning about the magic of trees today, please leave us a five-star review. Yeah. Just scroll down on your podcast app and tap those five shiny stars. It really helps us make more episodes for you. Oh, and don't forget to check out our site kidopoly.com. We've got tons of fun learning games, activities, and cool stuff to explore there. It's so awesome over there. Want your name on the show? Just send us an email at hello at kidopoly.com. We absolutely love hearing from you. Thank you so much for exploring with us today. Keep asking big questions. See you next time on Science Is Not Boring. Bye, everyone.