Respiration
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During respiration, oxygen is taken into the blood stream (through the alveolus in the lungs) and carbon dioxide is taken from the blood stream (through the alveolus in the lungs). Carbon Dioxide then exits the body through exhalation, whereas oxygen is taken to cells around the body to produce energy.
Animals obtain carbohydrates, like sugar, by eating them. Plants make their own carbohydrates. They get carbon dioxide from the environment and their energy from the sun. Plants store the Sun's energy in carbohydrates like sugar.