Respiration and Photosynthesis
Note that the equation for respiration shown in figure 10-1 is the reverse of
that for photosynthesis. Whereas photosynthesis takes carbon dioxide out of
the atmosphere, respiration restores carbon dioxide to the atmosphere. These
two processes, then, exist in precise balance. In other words, all the world’s
photosynthesis is in balance with all the world’s respiration, decay (which is
also respiration), and burning of fuels. By these opposing processes, the
concentration of carbon dioxide in the atmosphere is maintained at a nearly
constant .03%. Carbon, then, is taken out of the atmosphere in one process
and returned to it in another. Approximately sixteen billion tons of carbon
are processed in this way every year. The cycle can be graphically represented
as shown in figure 10-6.
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| Figure 10-5 Respiration and photosynthesis are opposite types of reactions, and carbon
dioxide and oxygen go through cycles. |
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| Figure 10-6 A more detailed version of figure 10-5 |
