All AP Biology Resources
Example Questions
Example Question #4 : Understanding Emulsification
Bile salts make fat droplets more accessible to the enzyme __________.
pancreatic lipase
chymotrypsin
trypsin
pepsin
lingual lipase
pancreatic lipase
Once large fat clusters are broken down by bile salts to become smaller micelles, pancreatic lipase has more surface area to access fats. The enzymes are able to reach the fat droplet through the gaps between bile salts. Fats are not emulsified by bile yet in the mouth, so lingual lipase acts upstream of bile to hydrolize long chain hydrocarbons. The other answer choices are proteases.
Example Question #1 : Understanding Other Digestive Physiology
Which of the following enzymes does NOT directly contribute to protein digestion?
Pepsin
Chymotrypsin
Trypsin
Gastrin
Gastrin
Gastrin is secreted in the stomach, and stimulates the secretion of hydrochloric acid by parietal cells. The other three enzymes directly aid in the digestion of proteins. Trypsin and chymotrypsin are released from the pancreas into the duodenum, and pepsin digests proteins located in the stomach. Each of these has different cleavange targets within protein sequences and can be used as a restriction enzyme in experimental procedures.
Example Question #2 : Understanding Other Digestive Physiology
Which of the following functions is NOT accomplished by the liver?
Antibody creation
Blood filtration
Glycogen storage
Vitamin storage
Antibody creation
The liver is a very important organ with many interrelated functions, however, the liver is not responsible for the creation of antibodies. This is done by plasma cells, a key cell type in the immune system.
Example Question #3 : Understanding Other Digestive Physiology
Which of the following statements about the hormone secretin is false?
It is released when acid enters the duodenum, where it is secreted
All of these choices are correct
It stimulates bicarbonate secretion in the pancreas
It inhibits motility in the stomach
All of these choices are correct
Secretin is a hormone released by the duodenum in response to an influx of acid. The hormone targets the stomach, to reduce the amount of acid that can pass through to the small intestine, and the pancreas, to increase secretion of bicarbonate, which neutralizes the acidity.
Example Question #4 : Understanding Other Digestive Physiology
Which of the following statements about cholecystokinin (CCK) and gastrin is true?
Both hormones are secreted only by the duodenum
Both hormones target the stomach, but for different functions
Both hormones target the pancreas, but for different functions
Both hormones target the gall bladder to release bile
Both hormones target the stomach, but for different functions
Cholecystokini (CCK) targets the stomach to inhibit motility, while gastrin targets the stomach to increase motility. Gastrin is secreted by the duodenum and the stomach, but targets only the stomach. CCK, however, targets the stomach, pancreas, and gall bladder.
Example Question #41 : Systems Physiology
Which enzyme operates at the lowest pH?
Trypsin
Lipase
Carboxypeptidase
Pepsin
Amylase
Pepsin
Pepsin is the only enzyme out of the given choices that functions in the stomach, where the pH is very low (acidic). Trypsin, carboxypeptidase, and lipase all function within the small intestine, where the pH is usually more basic to neutralize the pH of chyme as food is digested. Amylase is found in saliva and functions in the mouth, where pH is about neutral.
Example Question #1 : Understanding Other Digestive Physiology
One of the functions of the liver is __________.
to act as the main storage center for bile
to produce insulin in its specialized beta cells
to physically digest food
to secrete epinephrine and norepinephrine
to produce bile, triglycerides, and cholesterol
to produce bile, triglycerides, and cholesterol
The liver has a large number of functions, including metabolizing toxins, synthesizing proteins, and storing glucose in the form of glycogen. The only answer choice that describes liver functions is the production of bile, triglycerides, and cholesterol.
The pancreas produces insulin from beta cells, the gall bladder stores bile, and the adrenal medulla secretes epinephrine and norepinephrine. Physical digestion takes place mainly in the mouth and stomach, not the liver.
Example Question #6 : Understanding Other Digestive Physiology
Which of the following statements about the pancreas is incorrect?
The pancreas secretes bicarbonate to neutralize chyme
The pancreas secretes hydrolytic enzymes through the pancreatic duct and into the small intestine
The pancreas secretes the hormones insulin and glucagon
The pancreas is the body's main site of glycogen storage
The pancreas is the body's main site of glycogen storage
Glycogen is stored primarily in cells of the liver and muscles. The pancreas is responsible for secreting hydrolytic enzymes into the small intestine via the pancreatic duct. Along with these digestive enzymes the pancreas releases bicarbonate, which reacts in an acid-base reaction with acidic stomach chyme to pervent it from damaging the intestine. The pancreas also releases insulin and glucagon, among other hormones.
Example Question #21 : Digestive Physiology
What macromolecule is digested first by chemical means?
Proteins
Fats
Nucleic acids
Carbohydrates
Carbohydrates
Carbohydrates begin their digestion in the mouth, where salivary amylase is produced.
Fats are emulsified by bile and digested by lipase in the small intestine. Nucleic acids are also digested in the small intestine by nucleases. Proteins begin their digestion in the stomach, where the low pH of gastric juice begins the breakdown process and pepsin begins to cleave peptide bonds. Protein digestion continues in the small intestine with other protease enzymes.
Example Question #22 : Digestive Physiology
Which of the following is a true statement with regard to digestive enzymes?
Proteases only exist in the mouth
Proteases only exist in the small intestine
Most water absorption is performed in the stomach
Amylase breaks down amino acids
Lipases digest fats
Lipases digest fats
Amylase breaks down starch in the mouth and small intestine. Proteases are found in the stomach and small intestine. Water absorption occurs in the intestines (mostly the large intestine). Lipases break down lipids; fats are a type of lipid.