The absorptive surface of the small intestine is greater than that of other human digestive organs because of its length and the presence of

A. alveoli

B. neurons

C. villi

D. nephrons

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Answer Explanation:

C) villi

- Correct: The absorptive surface of the small intestine is greatly increased due to the presence of villi. Villi are finger-like projections that line the inner surface of the small intestine. These structures greatly increase the surface area available for absorption. Each villus contains capillaries and lacteals (lymphatic vessels) that absorb nutrients from digested food. The large surface area provided by the villi allows for more efficient absorption of nutrients such as carbohydrates, proteins, fats, vitamins, and minerals.

A) alveoli

- Incorrect: Alveoli are tiny air sacs in the lungs where gas exchange occurs during respiration. They are not found in the digestive system and do not contribute to the absorptive surface of the small intestine.

B) neurons

- Incorrect: Neurons are nerve cells that transmit signals throughout the body, including the digestive system. While neurons play a role in regulating digestion and other digestive processes, they do not directly contribute to the absorptive surface of the small intestine.

D) nephrons

- Incorrect: Nephrons are the functional units of the kidneys responsible for filtering blood and producing urine. They are not part of the digestive system and do not contribute to the absorptive surface of the small intestine.

Therefore, the Correct Answer is C.

More Questions on Digestive System Practice Exam 1

Question 1:

Salmonella bacteria can cause humans to have stomach cramps, vomiting, diarrhea, and fever. The effect these bacteria have on humans indicates that Salmonella bacteria are

A. predators

B. pathogenic organisms

C. parasitic fungi

D. decomposers

The Correct Answer is B.

B) pathogenic organisms

- Correct: Salmonella bacteria are pathogenic organisms, meaning they can cause disease in humans and other animals. When ingested, Salmonella bacteria can lead to symptoms such as stomach cramps, vomiting, diarrhea, and fever. Salmonella infection, known as salmonellosis, is a common cause of foodborne illness, often associated with the consumption of contaminated food, particularly undercooked poultry, eggs, and unpasteurized dairy products.

A) predators

- Incorrect: Predators are organisms that hunt, kill, and consume other organisms for food. Salmonella bacteria are not predators; they do not actively hunt and consume other organisms.

C) parasitic fungi

- Incorrect: Salmonella bacteria are not parasitic fungi. Parasitic fungi are fungi that derive nutrients from living organisms, often causing harm or disease. Salmonella bacteria are a distinct type of pathogenic bacteria, not fungi.

D) decomposers

- Incorrect: Decomposers are organisms that break down and feed on dead organic matter, aiding in the process of decomposition. Salmonella bacteria are not decomposers; they are pathogenic bacteria that can cause illness in humans and animals.


Question 2:

Which components of the human diet contain the greatest amounts of sugars and starches?

A. meat and eggs

B. fruits and vegetables

C. minerals and milk

D. water and vitamins

The Correct Answer is B.

B) fruits and vegetables

- Correct: Fruits and vegetables contain the greatest amounts of sugars and starches in the human diet. Both fruits and vegetables are rich sources of carbohydrates, including natural sugars, fiber, and starches. These carbohydrates provide a readily available source of energy for the body. Examples of fruits with natural sugars include apples, bananas, and grapes, while starch-containing vegetables include potatoes, corn, and peas.

A) meat and eggs

- Incorrect: Meat and eggs are primarily sources of proteins and fats, not sugars and starches. They contain minimal amounts of carbohydrates.

C) minerals and milk

- Incorrect: Minerals are inorganic compounds essential for various physiological functions, and milk is a source of proteins, fats, and carbohydrates (mainly lactose, a sugar). While milk contains some sugars, fruits and vegetables typically contribute more significant amounts of sugars and starches to the diet.

D) water and vitamins

- Incorrect: Water and vitamins are essential components of the diet, but they do not contain sugars and starches. Water is a vital component for hydration, and vitamins are organic compounds required for various biochemical processes in the body.


Question 3:

Into which parts of the human digestive system are digestive enzymes secreted?

A. mouth, esophagus, stomach

B. stomach, small intestine, large intestine

C. mouth, stomach, small intestine

D. esophagus, stomach, large intestine

The Correct Answer is C.

A) Mouth, Esophagus, Stomach: This option is incorrect because while saliva in the mouth does contain digestive enzymes (such as amylase for breaking down carbohydrates), the esophagus is not a site of enzyme secretion. The stomach secretes gastric juices which primarily contain hydrochloric acid and pepsinogen (which is converted to pepsin, a protein-digesting enzyme), but the esophagus itself does not secrete digestive enzymes.

B) Stomach, Small Intestine, Large Intestine: This option is incorrect because while both the small intestine and the large intestine play crucial roles in digestion and absorption, enzyme secretion mainly occurs in the stomach and small intestine. The large intestine primarily absorbs water and salts and does not secrete digestive enzymes.

C) Mouth, Stomach, Small Intestine: This option is correct. Enzymes are secreted in the mouth (amylase), stomach (pepsin for protein digestion), and small intestine (various enzymes including pancreatic enzymes like lipase, protease, and amylase, as well as enzymes produced by the intestinal lining).

D) Esophagus, Stomach, Large Intestine: This option is incorrect because while the stomach does secrete digestive enzymes, the esophagus and large intestine do not. The large intestine primarily absorbs water and salts and does not secrete digestive enzymes.


Question 4:

Which food would provide the most roughage for the body?

A. baked fresh fish

B. lettuce-and-tomato salad

C. fried chicken breast

D. milkshake

The Correct Answer is B.

B) lettuce-and-tomato salad

- Correct: Lettuce-and-tomato salad would provide the most roughage for the body. Roughage, also known as dietary fiber or bulk, refers to the indigestible portion of plant foods that adds bulk to the stool and helps regulate bowel movements. Lettuce and tomatoes are both rich sources of dietary fiber. Lettuce, especially varieties like romaine or leaf lettuce, contains cellulose and other insoluble fibers, while tomatoes contain soluble fibers like pectin. Consuming a salad made of lettuce and tomatoes would provide a significant amount of roughage to the body, promoting digestive health and regular bowel movements.

A) baked fresh fish

- Incorrect: Fish does not contain significant amounts of dietary fiber. While fish is a valuable source of protein and other nutrients, it is not a source of roughage.

C) fried chicken breast

- Incorrect: Fried chicken breast does not contain significant amounts of dietary fiber. Additionally, frying can add unhealthy fats and calories to the chicken breast, further reducing its nutritional value in terms of roughage.

D) milkshake

- Incorrect: Milkshakes are typically made with milk, ice cream, and flavorings, none of which provide dietary fiber. In fact, milkshakes are generally low in fiber and may contain high amounts of sugar and fat, making them poor choices for increasing roughage intake.


Question 5:

If a person was unable to break down food particles into molecules that could be absorbed by the body, you would predict

A. there is a malfunction with the digestive system

B. there is a malfunction with the excretory system

C. there is a malfunction with the reproductive system

D. there is a malfunction with the circulatory system

The Correct Answer is A.

A) there is a malfunction with the digestive system

- Correct: Inability to break down food particles into molecules that can be absorbed by the body suggests a malfunction with the digestive system. The digestive system is responsible for the mechanical and chemical breakdown of food into smaller molecules, such as carbohydrates, proteins, and fats, that can be absorbed by the intestines and utilized by the body for energy, growth, and repair. If the digestive system is not functioning properly, it can lead to malabsorption of nutrients, resulting in nutritional deficiencies and related health issues.

B) there is a malfunction with the excretory system

- Incorrect: The excretory system is responsible for removing waste products from the body, primarily through the kidneys, urinary tract, and skin. While the excretory system plays a role in eliminating some metabolic waste products generated from the breakdown of nutrients, it is not primarily responsible for the breakdown of food particles into absorbable molecules.

C) there is a malfunction with the reproductive system

- Incorrect: The reproductive system is responsible for the production of gametes (sperm and eggs) and the facilitation of reproduction. It is not directly involved in the breakdown and absorption of food particles in the digestive process.

D) there is a malfunction with the circulatory system

- Incorrect: The circulatory system, comprising the heart, blood vessels, and blood, is responsible for transporting nutrients, oxygen, and other substances throughout the body. While the circulatory system transports nutrients absorbed by the digestive system to various tissues and organs, it does not directly participate in the breakdown of food particles into absorbable molecules.


Question 6:

Some vitamins are essential to an organism because they function as

A. coenzymes

B. auxins

C. hormones

D. neurotransmitters

The Correct Answer is A.

A) coenzymes

- Correct: Some vitamins function as coenzymes, which are molecules that assist enzymes in their catalytic activity. Coenzymes work together with enzymes to facilitate various biochemical reactions in the body. For example, certain B vitamins (such as thiamine, riboflavin, and niacin) act as coenzymes in energy metabolism, while vitamin K acts as a coenzyme in blood clotting. Without these essential vitamins, many metabolic processes in the body would be impaired, leading to various health problems.

B) auxins

- Incorrect: Auxins are plant hormones that regulate plant growth and development. They are not vitamins and do not function as coenzymes in biochemical reactions in organisms.

C) hormones

- Incorrect: Hormones are signaling molecules that regulate various physiological processes in organisms. While some vitamins may indirectly influence hormone production or function, they do not function primarily as hormones themselves.

D) neurotransmitters

- Incorrect: Neurotransmitters are chemical messengers that transmit signals between nerve cells (neurons) in the nervous system. They are not vitamins and do not function as coenzymes in biochemical reactions in organisms.

 


Question 7:

All of the following are organs of the digestive system except

A. the stomach

B. the mouth

C. the intestines

D. the heart

The Correct Answer is D.

A) The stomach - This is an organ of the digestive system. It plays a crucial role in breaking down food through the secretion of gastric juices, which contain enzymes and acids to begin the process of digestion. Therefore, option A is correct.

B) The mouth - The mouth is also an organ of the digestive system. It is where the process of digestion begins, as it is responsible for chewing and breaking down food into smaller pieces. Additionally, saliva produced in the mouth contains enzymes that start the chemical breakdown of food. Therefore, option B is correct.

C) The intestines - Both the small intestine and the large intestine are essential organs of the digestive system. The small intestine is where most of the absorption of nutrients from food occurs, while the large intestine absorbs water and salts from the material that has not been digested. Therefore, option C is correct.

D) The heart - The heart is not an organ of the digestive system. Instead, it is a part of the circulatory system responsible for pumping blood throughout the body. While the circulatory system works in conjunction with the digestive system to transport nutrients absorbed from the intestines to various tissues and organs, the heart itself is not directly involved in digestion. Therefore, option D is incorrect.


Question 8:

Which disorder would most directly interfere with the emulsification of fats?

A. bronchitis

B. gout

C. goiter

D. gallstones

The Correct Answer is D.

D) gallstones

- Correct: Gallstones would most directly interfere with the emulsification of fats. Emulsification of fats is primarily facilitated by bile, a digestive fluid produced by the liver and stored in the gallbladder. Gallstones are hardened deposits that form in the gallbladder, often consisting of cholesterol or bilirubin. These stones can obstruct the flow of bile from the gallbladder into the small intestine, impairing the emulsification of fats and leading to difficulties in fat digestion and absorption. This obstruction can result in symptoms such as abdominal pain, nausea, and indigestion.

A) bronchitis

- Incorrect: Bronchitis is inflammation of the bronchial tubes in the lungs and does not directly interfere with the emulsification of fats in the digestive system.

B) gout

- Incorrect: Gout is a form of arthritis characterized by the accumulation of uric acid crystals in the joints, typically affecting the feet. It does not directly interfere with the emulsification of fats in the digestive system.

C) goiter

- Incorrect: Goiter is an abnormal enlargement of the thyroid gland in the neck, often due to iodine deficiency or thyroid disorders. It does not directly interfere with the emulsification of fats in the digestive system.


Question 9:

In humans, structures that release digestive secretions directly into the small intestine include both the

A. salivary glands and the pancreas

B. gall bladder and the lacteals

C. villi and the salivary glands

D. pancreas and the gall bladder

The Correct Answer is D.

D) pancreas and the gallbladder

- Correct: Both the pancreas and the gallbladder release digestive secretions directly into the small intestine. The pancreas secretes pancreatic enzymes (such as amylase, lipase, and proteases) into the small intestine to aid in the digestion of carbohydrates, fats, and proteins. The gallbladder stores bile produced by the liver, which is released into the small intestine to aid in the emulsification and digestion of fats.

A) salivary glands and the pancreas

- Incorrect: While the pancreas releases digestive secretions directly into the small intestine, the salivary glands secrete saliva into the mouth, which contains enzymes (such as amylase) that begin the digestion of carbohydrates. Salivary glands do not release digestive secretions directly into the small intestine.

B) gall bladder and the lacteals

- Incorrect: The gallbladder stores bile produced by the liver, which is released into the small intestine to aid in fat digestion. Lacteals are lymphatic vessels found in the villi of the small intestine and are involved in the absorption of fats, but they do not release digestive secretions directly into the small intestine.

C) villi and the salivary glands

- Incorrect: Villi are finger-like projections in the small intestine that increase the surface area for absorption of nutrients but do not release digestive secretions directly into the small intestine. Salivary glands secrete saliva into the mouth to initiate the digestion of carbohydrates but do not release digestive secretions directly into the small intestine.


Question 10:

A branch of the nerve regulating the secretions of the stomach can be cut surgically. The decrease in hydrochloric acid secretion that would result from this procedure would be most helpful to an individual with

A. diarrhea

B. appendicitis

C. gallstones

D. ulcers

The Correct Answer is D.

D) ulcers

- Correct: The decrease in hydrochloric acid secretion resulting from the surgical cutting of a branch of the nerve regulating stomach secretions would be most helpful to an individual with ulcers. Ulcers are sores or lesions that develop in the lining of the stomach, small intestine, or esophagus due to factors such as infection with Helicobacter pylori bacteria, prolonged use of nonsteroidal anti-inflammatory drugs (NSAIDs), or excessive alcohol consumption. Hydrochloric acid plays a significant role in the formation and exacerbation of ulcers by increasing the acidity of the stomach, which can irritate and erode the lining of the gastrointestinal tract. Therefore, reducing hydrochloric acid secretion can help alleviate the symptoms and promote healing of ulcers.

A) diarrhea

- Incorrect: Decreasing hydrochloric acid secretion would not directly address the underlying causes of diarrhea, which may be related to infections, dietary issues, or other factors affecting gastrointestinal motility and water absorption.

B) appendicitis

- Incorrect: Appendicitis is inflammation of the appendix, a small pouch located near the junction of the small and large intestines. Decreasing hydrochloric acid secretion would not directly affect the development or treatment of appendicitis.

C) gallstones

- Incorrect: Gallstones are hardened deposits that form in the gallbladder and can obstruct the flow of bile. Decreasing hydrochloric acid secretion would not directly address the formation or treatment of gallstones, as they are primarily composed of cholesterol or bilirubin, not affected by changes in stomach acid levels.