AP Biology : Digestive Physiology
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Example Questions
Example Question #31 : Digestive Physiology
Which of the following does not take place in the small intestine?
Proteins are broken down into amino acids by pepsin
Fats are emulsified into smaller particles by bile
Carbohydrates are broken down into simple sugars by pancreatic amylase
Fats are broken down into glycerol by pancreatic lipase
Fats are broken down into fatty acids by pancreatic lipase
Proteins are broken down into amino acids by pepsin
Complete digestion takes place in the small intestine, but pepsin is present in the stomach where it breaks down proteins to peptides. The pH in the stomach is very low, and pepsin, like all enzymes, has an optimal temperature and pH at which it functions best. For pepsin, this pH happens to be very low. The other enzymes mentioned that function in the small intestine have optimal pH's close to the pH of the small intestine (which is slightly alkaline due to the pancreas secreting bicarbonate).
Example Question #32 : Digestive Physiology
Which of the following enzymes breaks down starches and carbohydrates?
Peptidase
Trypsin
Nuclease
Amylase
Lipase
Amylase
Amylase is the enzyme that breaks down starches and carbohydrates. There are two types, salivary amylase and pancreatic amylase. Salivary amylase is produced in the mouth by the salivary glands and it is one of the first enzymes that begins the process of food digestion.
Example Question #33 : Digestive Physiology
Which organ secretes proteolytic zymogens (inactive enzymes) that are present in small intestine?
The stomach
The small intestine
The liver
The pancreas
The large intestine
The pancreas
The pancreas is responsible for secreting proteolytic zymogens, such as trypsinogen, into the small intestine. This is triggered by the presence of undigested food (chyme) in the duodenum.
Example Question #34 : Digestive Physiology
The __________ synthesizes bile while the __________ stores and secretes it into the small intestine.
small intestine . . . pancreas
liver . . . gallbladder
pancreas . . . liver
stomach . . . gallbladder
liver . . . stomach
liver . . . gallbladder
Bile is synthesized in the liver and secreted by the gallbladder into the small intestine upon the appearance of acidic chyme in the duodenum. Bile contains salts that emulsify (solubilize) fats, which is a necessary step in their digestion. If the gallbladder is removed, the liver can take over both roles.
Example Question #35 : Digestive Physiology
What is the major enzyme in saliva that acts on carbohydrates?
Lingual amylase
Salivary trypsin
Lingual lipase
Lingual pepsin
Salivary amylase
Salivary amylase
Salivary amylase in the mouth targets large starch molecules and begins the digestion process to a monosaccharide (i.e. glucose). Salivary amylase secretion is stimulated by the recognition of starch on sweet taste receptors, and is carried out by the salivary glands (parotid, submandibular, and sublingual).
Example Question #36 : Digestive Physiology
Zymogens are excreted in the digestive system in order to __________.
Be more active than enzymes and break down food quickly
Be more resilient to the low pH of the stomach
To save energy by producing an effective, but less costly enzyme
Prevent accidental digestion of the body's proteins rather than dietary protein
Be more specific to digestion
Prevent accidental digestion of the body's proteins rather than dietary protein
Zymogens are inactive forms of enzymes that are secreted in order to prevent the accidental digestion of the body's important proteins (i.e. other enzymes, structural proteins). These zymogens are then activated through further processing in the compartments in which they are meant to work.
Example Question #37 : Digestive Physiology
Enzymes such as trypsin and chymotrypsin in the small intestine break __________ into __________.
fats . . . lipids
carbohydrates . . . monosaccharides
carbohydrates . . . diasaccharides
nucleic acids . . . nucleotides
proteins . . . amino acids
proteins . . . amino acids
Trypsin and chymotrypsin belong to a family of enzymes that are "proteolytic". This means that they target proteins and break them down into their building blocks called amino acids.
Example Question #38 : Digestive Physiology
Amylase is a digestive enzyme responsible for breaking down which macromolecules found in food?
Nucleic acids
Lipids
Carbohydrates
None of these
Proteins
Carbohydrates
The correct answer is carbohydrates because amylase is the enzyme that is able to break these macromolecules down into smaller parts. There are two kinds of amylase found in the body, salivary amylase in the mouth and pancreatic amylase in the pancreas. Both of these are involved in the breakdown of carbohydrates in digestion.
Example Question #39 : Digestive Physiology
Which digestive system organ secretes enzymes vital for lipid digestive, and where are these enzymes introduced into the digestive tract?
Enzymes from the pancreas are introduced into the duodenum
Enzymes from the liver are introduced into the stomach
Enzymes from the liver are introduced into the colon
Enzymes from the pancreas are introduced into the stomach
Enzymes from the pancreas are introduced into the duodenum
Lipase is synthesized and secreted from the pancreas into the duodenum of the small intestine. Lipase plays a key role in the digestion of lipids.
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