carbon is found in all living things. carbon atoms move constantly through
living organisms, the oceans, the atmosphere, and the earth’s crust in what is
known as the carbon cycle. the directions taken by carbon atoms through this
cycle are very complicated and can take millions of years to make a full circle.
all animals, from humans to the dinosaurs are part of the carbon cycle. when
animals eat food, they get carbon in the form of carbohydrates and proteins.
in animals, oxygen combines with food in the cells to produce energy for daily
activity and then gives off carbon. the carbon combines with oxygen to form
carbon dioxide (co2) and is released back into the atmosphere as a waste
product when animals breathe and exhale.
from 145-65 million years ago, earth was much
hotter than today and covered with dense,
tropical swamp forests. the trees and other
plants were immense and
provided an endless supply of
food for the giant animals that
roamed the land. somewhere in
the air above one of these
forests, a lone carbon atom has joined
up with two oxygen atoms to form a molecule of co2.
the co2 molecule was sucked into the tiny holes (stomata) on the leaf of a
fern plant and joined with sunlight, chlorophyll and water to make food and
energy in the plant’s cells through photosynthesis. the oxygen (o2) from the
co2 molecule was sent back into the atmosphere; the carbon atom (c) was
detached and used to make a molecule of sugar.
if that carbon atom had been eaten instead, a totally
different situation would have developed. let’s say
that a giant plant-eating dinosaur (herbivore) ate the
fern for breakfast, and swallowed the carbon in the
fern in the form of carbohydrates and proteins. in
the process of respiration, oxygen combined with
the carbohydrates and proteins in the dinosaur’s cells
to provide energy for its daily activity.
are output and input work respectively.
