Parietal cells within the stomach lining secrete hydrochloric acid that lowers the pH of the stomach. A low pH (1.5 to 2) activates pepsin. Acetylcholine, gastrin, and histamine stimulate the proton pump in parietal cells to release hydrogen ions and decrease pH.
Carbon would build up in the atmosphere.
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Answer:
The ratios of thymine and adenine were similar, as were the ratios of guanine and cytosine.
Explanation:
deoxyribose + phosphate group + thymine