Why does the combination of respiration and photosynthesis allow a sealed environment to survive almost indefinitely? A. They recycle each other's materials.
B. They do not allow a sealed ecosystem to survive.
C. They each sustain a different part of the food chain.
D. They create new energy to be used.

A. They recycle each other's materials.

Explanation:

Respiration brings out carbon dioxide which is good for photosynthesis.

And photosynthesis also brings out oxygen used for respiration.

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in the year 2850, humans successfully colonized mars. the martian modules that were constructed could hold only a small population of people. it is now a century later, and the population on mars has grown to 600 people. of the current mars population, 45 people express the recessive phenotype for phenylketon- uria (pku) syndrome (pp genotype).

explanation: