AP Biology : Understanding the Lower Digestive tract: Small Intestine to Rectum

Study concepts, example questions & explanations for AP Biology

varsity tutors app store varsity tutors android store

Example Questions

Example Question #1 : Understanding The Lower Digestive Tract: Small Intestine To Rectum

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

Possible Answers:

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

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

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

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.

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 #1292 : Ap Biology

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

Pancreas

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

Liver

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

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

The pancreatic duct 

Lacteal vessels

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

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

Possible Answers:

Duodenum, jejunum, ileum

Jejunum, ileum, duodenum

Duodenum, ileum, jejunum

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 #1295 : Ap Biology

Which is not a structure of the small intestine?

Possible Answers:

Jejunum

Villi

Ileum

Ilium

Duodenum

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 #7 : Understanding The Lower Digestive Tract: Small Intestine To Rectum

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

Possible Answers:

Lipases

Bile salts

Trypsin

Bicarbonate

Pepsin

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.

Example Question #7 : Understanding The Lower Digestive Tract: Small Intestine To Rectum

What is the purpose of microvilli in the small intestine?

Possible Answers:

Increase contractility

Increase surface area

Decrease contracility

Decrease surface area

Correct answer:

Increase surface area

Explanation:

Microvilli are found at the microscopic level within the digestive tract to help increase surface area. The increased surface area aids in the absorption of nutrients as they pass through the small intestine. Microvilli allow for folds in the digestive tract, which in turn, increase the amount of area available for nutrient absorption.

Learning Tools by Varsity Tutors

Incompatible Browser

Please upgrade or download one of the following browsers to use Instant Tutoring: