GRE Subject Test: Biology : Digestive System

Study concepts, example questions & explanations for GRE Subject Test: Biology

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Example Questions

Example Question #1 : Understanding Digestive Structures

What organ releases digestive enzymes into the duodenum?

Possible Answers:

Liver

Gall bladder

Pancreas

Spleen

Correct answer:

Pancreas

Explanation:

The majority of chemical (enzymatic) digestion occurs in the duodenum, the first segment of the small intestine. Proteases, amylase, lipases, and other enzymes are secreted into the duodenum from the pancreas. These enzymes are used to digest proteins, carbohydrates, and lipids, respectively.

The liver produces bile, which is stored in the gall bladder. During digestion, bile is released to help emulsify fats for digestion. The spleen is part of the lymphatic system, and is not involved in digestion.

Example Question #1 : Digestive System

Which organ is responsible for releasing the majority of digestive enzymes into the small intestine?

Possible Answers:

Gall bladder

Pancreas

Liver

Stomach

Correct answer:

Pancreas

Explanation:

The small intestine is the primary site of digestion and absorption in the body. This chemical digestion is possible thanks to the digestive enymes secreted by the pancreas.

Example Question #1 : Digestive System

Which of the following is NOT a function of the liver?

Possible Answers:

Drug detoxification

Bile storage

Bile formation

Creation of proteins in the plasma

Correct answer:

Bile storage

Explanation:

While it is true that the liver creates and secretes bile, storage of bile is accomplished by the gall bladder.

Example Question #1 : Digestive System

-amylase, found in saliva, plays a role in the digestion of what compounds?

Possible Answers:

Proteins

Amino Acids

All of these will be digested by -amylase

Carbohydrates

Fats

Correct answer:

Carbohydrates

Explanation:

The correct answer is carbohydrates.

Salivary amylase can only digest carbohydrates. Proteases further along in the digestive pathway breakdown proteins, while lipases digest fats. Amino acids are the product of digested proteins.

Example Question #1 : Digestive System

Which of the following macromolecules is broken down by pepsin in the stomach?

Possible Answers:

Nucleic acids

Proteins

Carbohydrates

Lipids

Correct answer:

Proteins

Explanation:

Pepsinogen is released by chief cells into the stomach lumen. In the presence of hydrochloric acid (secreted by parietal cells), this inactive enzyme will be cleaved, creating pepsin. Pepsin is a protease responsible for breaking down proteins that enter the stomach.

Carbohydrates are digested by amylase enzymes, lipids are digested by lipases, and nucleic acids are digested by nucleases.

Example Question #2 : Digestive System

Which organ is responsible for creating bile?

Possible Answers:

Pancreas

Stomach

Gall bladder

Liver

Correct answer:

Liver

Explanation:

Bile is a salt solution used to emulsify fats in the small intestine in order to facilitate absorption. It is created by the liver, but stored in the gall bladder. During digestion, the bile is released from the gall bladder into the duodenum.

The stomach is mainly responsible for mechanical digestion, caused by smooth muscle contractions, and a small amount of protease function. The pancreas secretes a number of digestive enzymes into the duodenum to facilitate digestion of macromolecules. Neither organ is involved in the production of bile.

Example Question #4 : Digestive System

Which is a correct association for cell type and products in the islets of Langerhans?

Possible Answers:

 cells secrete insulin

 cells secrete insulin

 cells secrete glucagon

 cells secrete glucagon

 cells secrete somatostatin

Correct answer:

 cells secrete glucagon

Explanation:

The islets of Langerhans contain the endocrine pancreatic cells. 3 cell types within are the , and  cells.  cells secrete glucagon,  cells secrete insulin, and  cells secrete somatostatin.

Example Question #3 : Digestive System

A patient presents to the hospital with the complaint of pain in his abdomen. Imaging reveals ulcers in his upper small intestine. Further tests reveal that the ulcers are caused by acid entering the small intestine not being properly neutralized.

What organ in the digestive system is malfunctioning, causing these acidic secretions to harm the small intestine?

Possible Answers:

Liver

Stomach

Pancreas

Gall bladder

Correct answer:

Pancreas

Explanation:

Answering this question requires you to know which organ assists in neutralizing acidic chyme once it enters the small intestine. This is the responsibility of the pancreas, which secretes bicarbonate ions. This helps raise the pH of the chyme in the small intestine, and prevents damage.

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