Answer to Question 1
B
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After the cell has produced all substances necessary for formation of a new cell, or daughter cell, it undergoes cell division. This occurs during the M phase of the cell cycle. During this phase, the cell splits to form two identical daughter cells, a process called mitosis. The S phase involves the actual synthesis of DNA. In the G2 phase, the cell produces all the substances required for manufacture of the mitotic spindles.
Answer to Question 2
A
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Gastrin and the parasympathetic system stimulate histamine-2 receptors near the parietal cells, causing the cells to release hydrochloric acid into the lumen of the stomach. Other digestive enzymes are released appropriately, in response to proteins and carbohydrates, to begin digestion. Peptic ulcers can develop when there is a decrease in the protective mucosal layer or an increase in acid production. Research indicates that people who eat a spicy diet everyday are less prone to stomach ulceration; the stomach does not neutralize the hydrochloric acid but the highly alkaline duodenum neutralizes the pH when chyme arrives from the stomach. Acid does not flow from the small intestine to the stomach.