You may have seen those commercials where a ray of sun shines down into a bowl and the light turns into cereal.  But how does sunshine really turn into food?  Do plant leaves work like sponges that soak it in?  Or are their twigs like straws sipping it like lemonade?  There is a lot more to it than that.  Let's look at how plants really turn sun into food so you can laugh the next time one of those commercials comes on.

Sunlight and plants are making sugar all day.


Oh to be able to make your own sugar!  All you would need is a handful of dirt and some sunshine and you would be the most popular kid on the playground.  What are plants' secrets?  An autotroph is any living thing, such as a plant, that can make its own food.  Most of these use energy from the sun, but some use other things too.  Every time you breathe out, you let out a little part of the fuel that plants need to use with sunlight to make sugar.  This fuel is everywhere, which means you can find plants in the most surprising of places.  They are in the desert, in freezing climates, even at the bottom of the ocean.  Plant life has stretched far and wide across the world, but that doesn't mean turning this fuel into food is simple.

A kelp forest turns sunlight into sugar? I thought they were just places for fish to hide.


So wait, if plants only need a part of the air, why are there no plants hanging from the clouds?  There are a few more ingredients that they need for their cells, too.  First, they need sunshine.  Dirt gives vitamins and a safe place for their roots to cling while their leaves catch all this important stuff.  Photosynthesis is the name for when living things turn water, air, and light from the sun into sugar.  While going through this process, they let out the part of air that people need to use the energy from the food we eat.  That's right, we breathe in the stuff that plants give off.  Next time you are walking on the sidewalk, look at what comes out of the back of a running car.  You will see it giving off exhaust, or what is left over, when it burns gas and oil.  The part of air we breathe in is what plants give off when they make sugar.

I think this guy needs to have his car tuned.


Just in case you had not noticed, most plants are not very sweet when you bite into them.  If they were, you would be gobbling down salad like it was ice cream.  This is because plants use the sugar they make and turn it into more leaves and stems.  Cellular respiration is when cells change oxygen and sugar into energy they can use.  If using sunlight to make sugar is like making dinner, then this step is eating it.  The plants may have gobbled up all the sugar before you got a chance to eat it, but hey, they turned it into something healthy.

Now what does this have to do with you?  When you eat this sugar-filled plant, you are taking in all of its hard work.  You mix this with the stuff the plants breathed out, or air, and put them together to make your own energy.  Transferred energy is when energy moves from one place to another, like when a living thing eats a plant to use its energy.  It might seem unfair to steal that plant's hard work, but we pay them back by breathing out the stuff they need every day.  Isn't that sweet?

So the next time you see some light from the sun turn into cereal like magic, think of all the steps they are missing.  Where is the photosynthesis?  Where is the cellular respiration?  If making food was that easy, life would be a lot easier.  Go ahead.  You can scream at the TV a little bit.  You are a scientist.  You know about these things.

References:

Academic Kids.  "Autotroph."  Academic Kids, 2005.  <http://www.academickids.com/encyclopedia/index.php/Autotroph>

Kids Research Express. "Cellular Respiration." KRE, 2010. <http://kidsresearchexpress-5.blogspot.com/2008/08/cellular-respiration.html>