AP Biology : Understanding the Upper Digestive Tract: Mouth to Stomach

Study concepts, example questions & explanations for AP Biology

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Example Questions

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Example Question #1 : Understanding The Upper Digestive Tract: Mouth To Stomach

In which component of the digestive tract does no digestion occur?

Possible Answers:

Mouth

Small intestine

Esophagus

Stomach

Correct answer:

Esophagus

Explanation:

The esophagus is responsible for transporting food from the mouth to the stomach via peristalsis, which consists of smooth muscle contractions, but does not help digest the food content in the process. The mouth, stomach, and small intestine, however, all help in the process of food digestion. The mouth introduces enzymes in the saliva, the stomach introduces pepsin, and the small intestine introduces a number of other enzymes for digestion of macromolecules.

Example Question #1 : Systems Physiology

Which of the following choices incorrectly pairs a digestive enzyme with the digestive tract component in which it is found?

Possible Answers:

Pepsin is found in the stomach

All choices successfully pair a digestive enzyme with the digestive tract component in which it is found

Cholecystokinin is found in the mouth

Salivary amylase is found in the mouth

Correct answer:

Cholecystokinin is found in the mouth

Explanation:

Cholecystokinin (CCK) is a hormone released by the duodenum to signal and stimulate accessory organs for digestive enzymes. Salivary amylase digests starch in the mouth, while pepsin is used to digest proteins in the stomach.

Example Question #1 : Digestive System

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

Possible Answers:

Forms urea

Produces methane

Produces bile

Detoxes chemicals from the blood

Correct answer:

Produces methane

Explanation:

Methane is produced in the cecum as a result of blind outpocketing, during which E. coli organisms release the gas as a biproduct of digestion. Detoxing chemicals from the blood, forming urea, and producing bile are just three of the functions of the liver.

Example Question #3 : Digestive System

Which of the following is not a part of the pathway of food through the digestive tract?

Possible Answers:

Mouth

Pharynx

Esophagus

Larynx

Stomach

Correct answer:

Larynx

Explanation:

Food travels in this order through the digestive tract: mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus.

The larynx is commonly confused with the pharynx due to their similar names, but it is actually involved in speaking or making sounds. The pharynx splits into the trachea and esophagus. Food and liquids travel down the esophagus, while air travels down the trachea; the larynx is located at the top of the trachea.

Example Question #2 : Digestive System

Which structure separates the esophagus from the mouth?

Possible Answers:

Pharynx

Nasal sinus

Pyloric sphincter

Trachea

Stomach

Correct answer:

Pharynx

Explanation:

After entering the mouth, food is transferred to the pharynx before entering the esophagus. The pharynx is located immediately above the epiglottis, meaning that both food and air can enter the pharynx. The epiglottis covers the trachea to prevent food from entering, and forces food to travel down the esophagus instead. After food travels through the esophagus it enters the stomach. The pyloric sphincter then separates the stomach from the small intestine.

Example Question #3 : Systems Physiology

What structure prevents a bolus from entering the trachea?

Possible Answers:

Tongue

Tonsils

Pharynx

Epiglottis

Larynx

Correct answer:

Epiglottis

Explanation:

The epiglottis is a structure that folds forward to cover the trachea when swallowing. It helps to direct food to the esophagus instead of the trachea, preventing liquids and solids from entering the lungs.

Example Question #6 : Understanding The Upper Digestive Tract: Mouth To Stomach

In which region of the upper digestive tract does food transition into chyme?

Possible Answers:

The mouth

The sublingual salivary glands

The stomach

The esophagus

The liver

Correct answer:

The stomach

Explanation:

Chyme is formed during the initial breakdown of food. Food is turned into chyme in the stomach due to the combination of smooth muscle contractions and the chemical action of hydrochloric acid. These processes serve to digest the food both mechanically and chemically.

Example Question #4 : Digestive System

Which of the given answer choices is not a function of the liver? 

Possible Answers:

Production of glycogen

Detoxification

Storage of vitamins

Production of insulin

Production of bile

Correct answer:

Production of insulin

Explanation:

The liver produces bile, which is then stored in the gall bladder. It also stores vitamins and iron, and produces glycogen. The liver is also responsible for detoxification of several metabolites, but it does not produce insulin. Insulin secreted by the pancreas. Other functions of the liver include: synthesis of blood proteins, breakdown of lipids, recycling red blood cells, and glycogen breakdown.

Example Question #2 : Systems Physiology

Through which sphincter will a bolus pass to enter the stomach? Is this under control of the parasympathetic of sympathetic division of the autonomic nervous system?

Possible Answers:

Gastroesophageal sphincter, which is under control of the sympathetic nervous system

Urethral sphincter, which is under control of the sympathetic nervous system

Pyloric sphincter, which is under control of the parasympathetic nervous system

Gastroesophageal sphincter, which is under control of the parasympathetic nervous system

Pyloric sphincter, which is under control of the sympathetic nervous system 

Correct answer:

Gastroesophageal sphincter, which is under control of the parasympathetic nervous system

Explanation:

The contraction and relaxation of a layer of smooth muscle at the junction of the esophagus (-esophageal) and the stomach (gastro-) allows for the bolus to pass into the stomach upon relaxation, and by contraction keeps the bolus, acid, and other stomach contents from regurgitating into the esophagus from the stomach. This sphincter is under vagus nerve control, thus, the parasympathetic nervous system. 

Example Question #9 : Digestive System

What is the correct order that a bolus of food will pass through the small intestine?

Possible Answers:

Duodenum, ileum, jejunum

Jejunum, ileum, duodenum

Ileum, duodenum, jejunum

Jejunum, duodenum, ileum

Duodenum, jejunum, ileum

Correct answer:

Duodenum, jejunum, ileum

Explanation:

The correct order that the food will pass as is first the duodenum, then the jejunum and finally the ileum. These are all sections or portions of the small intestine, the organ responsible for the vast majority of absorption of nutrients from food before it is passed on to the large intestine, where water, vitamins, minerals, and any other remaining nutrients are absorbed into the body.

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