Key Concept 1: People and animals exhale carbon dioxide during
respiration.
There are two kinds of respiration:
1) the inhaling of oxygen and exhaling of carbon dioxide by animals with
lungs and
2) the absorption of oxygen and release of carbon dioxide waste at the
cellular level.
Most students know that blood flows in an animals body. One job of
those thousands of blood vessels is to carry oxygen from the lungs to
every cell, and then carry the discarded carbon dioxide waste from every
cell back to the lungs where it is exhaled. Plants need this exhaled carbon
dioxide for survival.
Key Concept 2: Plants use carbon dioxide, water, and sunlight to
produce their own food, releasing oxygen as a waste product.
During photosynthesis, plants absorb sunlight and carbon dioxide
through their leaves. There, a special chemical process combines the water
absorbed by plant roots with the sunlight and carbon dioxide to produce
glucose, a sugar plants use as food for growth. Plant cells release oxygen
as a waste product into the air. This oxygen is needed by animals for
survival.
Key Concept 3: In order to survive, people and animals inhale the
oxygen released by plants.
Plants release oxygen into the air which animals inhale. During respiration,
this inhaled oxygen is carried from the lungs by blood vessels to the heart
which pumps the oxygen rich blood and other nutrients to each body cell for
energy and growth. Plants also consume oxygen during respiration when they
burn sugars to gain energy. At night, in the absence of photosynthesis, plants
absorb O2from the atmosphere and release CO2 like all other organisms.
Nature has provided an environment so that animals and plants can interact
together to provide necessities that each need for survival. During the process of
photosynthesis plants use sunlight, water, and carbon dioxide to produce food
(glucose or sugar) and release oxygen. Animals breathe in that oxygen and use
digested food to produce energy and carbon dioxide. Animals release carbon
dioxide into the air, which plants use and the cycle starts again. The process by
which animals and plants exchange gases is called the carbon dioxide/oxygen
cycle. When this cycle is in balance, both plants and animals will be able to
survive in an environment. The burning of fossil fuels has added an excess of
carbon dioxide into the air.