AP Biology : Systems Physiology

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #11 : Digestive Anatomy

Parietal cells in the stomach secrete which of these?

Possible Answers:

Pepsinogen

Pepsin

Bile salts

Mucus

Hydrochloric acid

Correct answer:

Hydrochloric acid

Explanation:

In the stomach, both hydrochloric acid and pepsinogen are secreted by gastric pits. Parietal cells in these pits secrete hydrochloric acid while chief cells in these pits secrete pepsinogen. Note that pepsinogen is inactive, and gets activated into pepsin via hydrochloric acid.

Example Question #12 : Digestive Anatomy

The esophagus is able to swallow liquids upside down, proving that swallowing is a process that does not depend on gravity. What is the name of this process?

Possible Answers:

flatulation

denaturation

salivation

esophageal emulsification

peristalsis

Correct answer:

peristalsis

Explanation:

Peristalsis is the correct answer here. Peristalsis is the process of muscles contracting and relaxing in order to facilitate movement.

Example Question #13 : Digestive Anatomy

Removal of the gall bladder from the human body would most likely result in which of the following?

Possible Answers:

An inability to digest proteins properly

An inability to digest starch properly

An inability to digest fats properly

An inability to digest carbohydrates properly

Correct answer:

An inability to digest fats properly

Explanation:

The gallbladder is found underneath the liver. The gallbladder is the storage place of bile, which helps to emulsify fats. Bile is necessary for the digestive system to break down fat. Removal of the gallbladder can result in fat malabsorption, which can present as loose stool.

Example Question #11 : Systems Physiology

Why are villi found in the small intestine, but not in the stomach?

Possible Answers:

The small intestine uses the villi to increase its surface area and facilitate absorption. Absorption does not occur in the stomach.

The villi allow multiple areas where digestive enzymes can be released by the small intestine. The stomach does not release digestive enzymes.

The villi act in a cilia-like motion and move food down the small intestine. Movement in the stomach is generated by smooth muscle contractions.

The small intestine uses villi to adhere to the food particles entering from the stomach, while the stomach has no need for such adhesion.

Correct answer:

The small intestine uses the villi to increase its surface area and facilitate absorption. Absorption does not occur in the stomach.

Explanation:

The villi are helpful in increasing the surface area of the small intestine. This greatly increases the absorptive capabilities of the small intestine. The stomach has no villi, and does not contribute to absorption of macromolecules.

Example Question #2 : Understanding The Lower Digestive Tract: Small Intestine To Rectum

Which of the following segments of the digestive system has the primary job of digesting food?

Possible Answers:

Colon

Ileum

Duodenum

Jejunum

Correct answer:

Duodenum

Explanation:

The duodenum, in the small intestine, is a site of protein, carbohydrate, and fat digestion.

The jejunum is a site of protein and fat absorption. The ileum is a site of salt, vitamin, and excess molecule absorbtion. The colon is a segment of the large intestine for water and ion absortion. Each of these work to absorb different molecules, but do not significantly contribute to their digestion.

Example Question #3 : Understanding The Lower Digestive Tract: Small Intestine To Rectum

Jim's body is able to produce bile salts, but unable to store it in large quantities. As a result, he cannot eat too much fat at once or it can be harmful to his digestive system. The pancreas and large intestine are not involved in bile storage.

Which of the following organs is Jim missing?

Possible Answers:

Gall bladder

Liver

Pancreas

He is not missing any organs. Rather, he has an infected large intestine.

Correct answer:

Gall bladder

Explanation:

The role of the gall bladder is to store bile salts, but it does not produce them. Rather, bile salts are produced by the liver and transported to the gall bladder for storage.

Example Question #12 : Systems Physiology

Nutrient-rich blood moves from the small intestine to the liver via which of the following structures?

Possible Answers:

The hepatic portal system 

The pulmonary circuit

Lacteal vessels

The pancreatic duct 

Correct answer:

The hepatic portal system 

Explanation:

The hepatic portal system involves the capillaries of the small intestine and capillaries of the liver. A portal system refers to two different capillary beds, connected by arterioles, that both receive blood before it returns to the heart for reoxygenation. The prefix "hepa-" refers to the liver.

The pancreatic duct transfers digestive enzymes from the pancreas into the lumen of the small intestine. Lacteal vessels receive fats from the small intestine and carry them into the lymphatic system. The pulmonary circuit refers to the region of the circulatory system that carries blood from the right ventricle to the lungs, and back to the left atrium.

Example Question #16 : Digestive System

Beginning at the stomach, what is the order of the parts of the small intestine?

Possible Answers:

Duodenum, jejunum, ileum

Duodenum, ileum, jejunum

Jejunum, ileum, duodenum

Ileum, duodenum, jejunum

Correct answer:

Duodenum, jejunum, ileum

Explanation:

When digested food exits the stomach, it passes through the pyloric sphincter and enters the duodenum, the first region of the small intestine. The duodenum is the introduction point for the pancreatic digestive enzymes, as well as the neutralization of stomach acid. The majority of chemical digestion occurs in the duodenum. The middle region of the small intestine is the jejunum, and the final region is the ileum. These regions are primarily responsible for nutrient absorption and have the largest concentration of microvilli. After passing through the ileum, the digested matter enters the large intestine.

Example Question #5 : Understanding The Lower Digestive Tract: Small Intestine To Rectum

Which is not a structure of the small intestine?

Possible Answers:

Ileum

Duodenum

Ilium

Villi

Jejunum

Correct answer:

Ilium

Explanation:

Food is converted into a bolus upon swallowing, then into chyme in the stomach. The chyme travels from the stomach into the first part of the small intestine, the duodenum. The chyme then moves through the jejunum, then through the ileum before entering the large intestine. Villi are finger-like projections of the small intestine that increase the surface area of the epithelium to maximize nutrient absorption. The ilium is a part of the hip bone.

Example Question #20 : Digestive System

Which of the following is not secreted by the pancreas into the duodenum?

Possible Answers:

Trypsin

Lipases

Bile salts

Pepsin

Bicarbonate

Correct answer:

Pepsin

Explanation:

Pepsin is a protein degrading enzyme that is released by the stomach. All the other choices are released by the pancreas into the duodenum.

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