Fresh air to breathe
Did you know that every green plant in the world is like a kind of
factory? It works from sunrise to sunset making food for itself. As it
produces food, it gives off an invisible gas called oxygen. The oxygen
from plants mixes with other invisible gases that make up the air.
Oxygen is a very important gas! People, and all other animals, must have
oxygen to live. When we breathe, our bodies take in the oxygen we need.
Without oxygen in the air, we would die.
People and other animals that live on land take oxygen out of the air
when they breathe. You might think that all the oxygen would soon be
used up. It would be, if it weren’t for the green plants! All day long,
they keep releasing oxygen into the air.
You can watch a plant make oxygen. You will need:
an Elodea plant (waterweed) a wide jar water
a funnel (a clear one if possible) a clear plastic tube or bottle your
kitchen sink
Lay the jar, funnel, and tube or bottle on their sides in the sink. Run
cool water in the sink deep enough to cover them and fill them
completely.
Put the Elodea plant in the jar. Next, slide the wide end of the funnel
into the jar and over the plant. Then slide the plastic tube or bottle
over the funnel. Stand the jar upright with the plant, funnel, and tube
in it, as shown.
After a while, you will see a few bubbles begin to rise through the
funnel. As the plant makes oxygen, the bubbles will move up through the
water. Soon the top of the tube will be filled with oxygen the Elodea
plant gives off as it makes food for itself.
An Elodea plant making oxygen
The funnel is over the Elodea plant, and the test tube is over the
funnel. The bubble is oxygen just made by the plant. Because oxygen is a
gas, the bubble is rising through the water.
After a while, the top of the test tube is filled with oxygen made by
the Elodea plant.
