GED Science : Digestive and Excretory Systems
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Example Questions
Example Question #1 : Digestive And Excretory Systems
What is the role of chief cells in the stomach?
To release hydrochloric acid
To prevent epithelial degradation by stomach acid
To release pepsinogen
To stimulate parietal cells to release hydrochloric acid
To release pepsinogen
The chief cells are responsible for releasing pepsinogen. Pepsinogen is an inactive enzyme that will only become activated in acidic conditions, such as those found in the stomach. Acid converts pepsinogen into pepsin, which helps chemically digest protein nutrients in the stomach.
Parietal cells release hydrochloric acid into the stomach, which activates pepsinogen. Goblet cells, or mucous cells, secrete mucous to help prevent degradation of the stomach lining.
Example Question #2 : Digestive And Excretory Systems
What is the name of the process by which food is moved through the esophagus via a wave-like contracting motion?
Peristalsis
Mastication
Segmentation
Emulsification
Peristalsis
The esophagus assists moving food into the stomach using a wave-like contracting motion called peristalsis. Swallowing initiates the process of peristalsis, but unlike swallowing, peristaltic contractions are not voluntary and are generated by smooth muscle.
Mastication is another term for "chewing." Emulsification refers to the grouping together of fat molecules when in an aqueous environment, particularly during digestion in the small intestine.
Example Question #3 : Digestive And Excretory Systems
Which part of the digestive system does not contribute to the chemical digestion of food?
Stomach
Esophagus
Small intestine
Mouth
Esophagus
Food is digested to some degree in many different parts of the digestive system. The mouth, stomach, and small intestine all contribute to food digestion. The mouth contains salivary amylase, which breaks down carbohydrates. The stomach contains pepsin, which breaks down proteins. The small intestine contains several enzymes, such as lipase and trypsin, and breaks down carbohydrates, lipids, and proteins.
The esophagus, however, does not contribute to chemical digestion in any way.
Example Question #4 : Digestive And Excretory Systems
What is the role of bile in digestion?
It acts as an acid to further break down the food
It prevents the degradation of the small intestine by enzymes
It helps emulsify fats
It aids in carbohydrate digestion
It helps emulsify fats
Bile is created by the liver and released into the small intestine from the gall bladder during digestion. Because fat tends to clump in the aqueous environment of the duodenum, bile helps to increase the surface area of fat, a process called emulsification. This helps lipase break down the fats adequately.
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