Question
(c) A group of students investigated the action of salivary amylase. The students: - collected a sample of salivary amylase - put a different mathrm(pH) solution and 5 mathrm(~cm)^3 of a food substance in each of 6 test tubes - added 1 mathrm(~cm)^3 of salivary amylase to each of the 6 test tubes - recorded the amylase activity after 10 minutes. The results are shown in the table. pH & 7 & 6 & 5 & 4 & 3 & 2 }(l) Amylase activity in arbitrary units & 12 & 10 & 3 & 0 & 0 & 0 (i) Name the food substance that amylase breaks down. Starch (ii) Suggest what happens to the breakdown of this substance when food reaches the stomach. Use information from the table to help you to answer this question.
Answer
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Harvey
Elite · Tutor for 8 years
Answer
Starch(ii) When food reaches the stomach, the breakdown of this substance (starch) is reduced or slowed down significantly.【Explanation】: As food moves into the stomach, it is exposed to gastric acid, which has a pH between 2 and 3—highly acidic. According to the given table, the activity of salivary amylase drops to zero at a pH of 4 and beyond. This suggests that the acidic environment of the stomach impairs the functioning of salivary amylase, hence slowing or halting completely the breakdown of starches until neutralized in the small intestine where another form of amylase (pancreatic amylase) picks up the job. 【Answer】: The breakdown of starch is slowed down or impaired in the stomach due to the acidity of the gastric juice which affects the amylase activity.
Explanation
Amylase is an enzyme that breaks down carbohydrates into simple sugars. The carbohydrates in regards to the human diet often come in the form of starch, which is present in foods such as potatoes, rice, and bread. Ergo, amylase breaks down starch.