Plants produce oxygen and animals and humans use oxygen. About 21 percent of
Earth's atmosphere is oxygen, enough for all living creatures. For many years, plants
and animals have kept a bargain. Animals breathe the oxygen produced by plants. At
the same time, plants use the carbon dioxide that animals exhale. They mix it with
water and sunlight to produce a sugar called glucose. As it turns out, glucose is the
basic energy source for both plants and animals. The waste produced by this process
is oxygen. The bargain between plants and animals has been in the right balance for
many millions of years. If we humans are smart enough not to upset that balance too
much, all life on Earth will benefit from it for millions of years to come.
1. Plants are able to use water, carbon dioxide. and sunlight to produce
glucose plus oxygen. What's the effect of this for animals?
2.
What might be a cause that would break the bargain between plants and
animale?