All AP Biology Resources
Example Questions
Example Question #1 : Understanding Stomach Enzymes And Cell Types
Which compound is correctly matched to the type of cell that produces it?
Parietal cells secrete pepsinogen
Parietal cells secrete mucous
Chief cells secrete pepsinogen
Chief cells secrete pepsin
Goblet cells secrete hydrochloric acid
Chief cells secrete pepsinogen
The stomach contains several cell types, each with a specific mechanism of action.
Chief cells produce pepsinogen, which is converted to pepsin by hydrochloric acid in the stomach. Parietal cells produce hydrochloric acid, allowing this conversion. Goblet cells produce the mucous lining of the stomach that protects the stomach epithelium from damage from the acidic environment of the gastric lumen.
Example Question #1 : Digestive Physiology
Which enzyme is correctly paired with the macromolecule that it digests?
Peptidase catabolizes lipids
Lipase catabolizes carbohydrates
Amylase catabolizes proteins
Peptidase catabolizes proteins
Peptidase catabolizes proteins
Amylase is an enzyme found in saliva and the small intestine that breaks starches down into sugars. The correct pairing for amylase would be carbohydrates.
Peptidases break peptide bonds, which are what hold amino acids together in proteins. Different peptidases are found in the stomach (pepsin) and the small intestine (trypsin). The correct pairing for peptidase is proteins.
Lipase is an enzyme that catalyzes the hydrolysis of triglycerides into free fatty acids in the small intestine. The correct pairing for lipase would be fats or lipids.
Example Question #2 : Digestive Physiology
Which of the following is most closely linked to the activation of pepsinogen?
G cell
Parietal cell
Chief cell
Goblet cell
Parietal cell
Pepsinogen is an inactive enzyme (zymogen) that is released by chief cells into the stomach lumen. In order to be activated, the enzyme must be at a very low pH. This is accomplished by hydrochloric acid, which is released by the parietal cells in response to stimulation by gastrin. Parietal cells are, thus, most closely linked to the activation of pepsinogen.
Gastrin is released by G cells. Goblet cells secrete the mucous lining of the stomach.
Example Question #2 : Understanding Stomach Enzymes And Cell Types
Which of the following cells in the stomach is necessary for the activation of pepsinogen?
Goblet cells
Parietal cells
G cells
Chief cells
None of these
Parietal cells
Pepsinogen is released by chief cells in the stomach, and is the zymogen form of pepsin. Pepsinogen requires an acidic environment in order to be converted to pepsin. Parietal cells release hydrochloric acid into the stomach lumen, thus activating the enzyme.
G cells and goblet cells secrete gastrin and mucous, respectively, into the stomach.
Example Question #2 : Understanding Stomach Enzymes And Cell Types
Which stomach cell type secretes gastrin?
G cells
Parietal cells
Oxyntic cells
Chief cells
Goblet cells
G cells
G cells secrete the hormone gastrin. Gastrin further stimulates stomach acid secretions via parietal (oxyntic) cells. Chief cells secrete pepsinogen, the inactive form of the enzyme pepsin, which degrades proteins. Goblet cells secrete mucous to protect the cells of the stomach from the acid.
Example Question #1 : Digestive Physiology
Which of the following enzymes becomes activated in a low pH environment?
Lysozyme
Trypsinogen
Chymotrypsinogen
Pepsinogen
Gastrin
Pepsinogen
The only one of the enzymes listed that becomes activated in the presence of an acidic (low pH) environment is pepsinogen. When activated, pepsinogen forms into pepsin which occurs in the stomach because of the (hydrochloric acid) present. Enzymes and/or hormones that have the suffix -ogen, or the prefix pro- are known as zymogens or prohormones, which are not active. Different environments/molecules activate these enzymes and proteins. This method of activation allows for more rapid usage, rather than having to synthesize these molecules from scratch when they are needed.
Example Question #3 : Digestive Physiology
How is the zymogen protease activated in the stomach?
It reacts with the hydrochloric acid to become pepsin
It binds to parietal cells to become pepsin
It is active upon secretion
It binds to chief cells to become pepsin
It gets cleaved by trypsin to become catalytically active
It reacts with the hydrochloric acid to become pepsin
To become active, hydrochloric acid in the stomach reacts with pepsinogen to make pepsin.
Example Question #6 : Understanding Stomach Enzymes And Cell Types
In the stomach, the __________ cell secretes __________.
parietal cell . . . pepsinogen
chief cell . . . hydrochloric acid
chief cell . . . pepsin
chief cell . . . pepsinogen
parietal cell . . . hydrochloric acid
chief cell . . . pepsinogen
The chief cells of the stomach secrete the proteolytic zymogen pepsinogen. This zymogen then becomes activated as pepsin in the stomach.
Example Question #3 : Understanding Stomach Enzymes And Cell Types
The __________ cell secretes __________ in order to reduce the pH of the stomach to increase food digestion.
parietal . . . hydrofluoric acid
chief . . . carbonic acid
parietal . . . bile
chief . . . hydrochloric acid
parietal . . . hydrochloric acid
parietal . . . hydrochloric acid
The parietal cells of the stomach begin secreting hydrochloric acid even upon the smell of food (before consumption takes place) in order to begin the digestion process. These cells are common targets of antacid medications to reduce acid reflux.
Example Question #1 : Digestive Physiology
The high concentration of __________ present in the stomach activates pepsinogen, allowing it to become active pepsin.
hydrochloric acid
undigested food
bile
saliva
ATP
hydrochloric acid
Hydrochloric acid, produced by the parietal cells of the stomach, activates the zymogen pepsinogen.