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The answer is enzymes.
Enzymes are biological catalysts, which means they decrease the amount of activation energy needed to start a reaction, therefore speeding up the rate of the reaction. They are part of the protein macromolecule group. Without them, our bodies would not process things efficiently or fast enough for us to live.
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The correct option is D.
Parietal cells are the epithelial cells which secrete hydrochloric acid and intrinsic factors. The cells are located in the gastric glands which are found in the linings of the walls of the stomach. The hydrochloric acid produced by the parietal cells helps in the conversion of the enzyme pepsinogen to pepsin during the digestion process.
Answer:
embryological evidence or fossil evidence. give the answer choices if you can. they are vestigial structures.
Explanation: