Animals eat other organisms to obtain food. They then break down the food to get energy and rearrange the molecules of their food into new molecules. One of those molecules is carbon dioxide. How is carbon dioxide recycled back into the food chain? (1 Point)\
Answers
Answer:
Explanation:
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.
The CO2 was a waste product and was flushed out from
the dinosaur’s body when he took a deep breath and
exhaled, hours after he digested and was still feeling
content from his big breakfast. The carbon that had been
a part of the leafy fern was released into the atmosphere.
When the dinosaur died, most of the carbon
atoms in his body went into the soil. Tiny
organisms, including bacteria, fungi and
scavengers, broke down the big carbon molecules
into smaller ones. By releasing these nutrients
from the dead tissue, the process of
decomposition made them available to other living
organisms in the ecosystem. Over many years, layers of soil, water and high
temperatures and pressures turned the dinosaur into a fossil. The bones that
remained gave up the carbon in them to the atmosphere.
Soon after, the fern died and sank into the muck at
the bottom of the swamp. Over thousands of years,
more plants grew in the swamp and their remains
also settled into the swamp, forming a layer of dead
plant material containing carbon several feet thick
called peat.
Soil and other materials slowly covered the ancient swamp and
buried the decaying plants under a thick layer of sediment.
The sediment hardened, turning into sedimentary rock. The
carbon atom was trapped in the remains of the swamp while
the high pressure of the layers slowly compressed the
material into “coal”.
Today people mine these ancient coal beds and burn
the coal in power plants to create electricity to fuel
industry, transport goods and people, and to warm
homes and businesses. Burning (combustion)
releases the energy stored in the carbon compounds
in the coal and reconnects the carbon atom with
oxygen in the air to form CO2 again. Animals do just the opposite of plants:
they take in air from the atmosphere, use the oxygen, and exhale the CO2.
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Every so often, CO2 molecules escaped being buried and floated along with
other CO2 molecules over the ocean surface.
In places where the water was warm, it
absorbed these molecules. Oceans soak up
huge amounts of carbon and help keep too
much CO2 from staying in the atmosphere.
Once our CO2 molecule was dissolved in the
ocean water, it could have been captured by
an ocean organism that used it to make its shell. There are trillions upon
trillions of ocean creatures of all sizes that capture atmospheric carbon in the
form of CO2 and use it to make calcium carbonate (CaCO3) shells in the
process of calcification.