39. Digestive System

Which of the following organs is incorrectly paired with its function?

a. Stomach—protein digestion

b. Large intestine—bile production

c. Small intestine—nutrient absorption

d. Pancreas—enzyme production

After finding a gene that causes a disease, researchers often introduce the defective allele into mice to create an animal model of the disease. Why are these models valuable?

a. They allow the testing of potential drug therapies without endangering human patients.

b. They allow the sequencing of the mutant allele.

c. They allow the production of large quantities of the defective gene product, usually a protein.

d. They allow the study of how the gene was transmitted from parents to offspring.

Earthworms, which are substrate feeders,

a. Feed mostly on mineral substrates.

b. Filter small organisms from the soil.

c. Are bulk feeders that ingest large pieces of food.

d. Eat their way through the soil, feeding on partially decayed organic matter.

Cellulose is fermented in which of the following structures in rabbits?

a. Small intestine

b. Cecum

c. Abomasum

d. Rumen

In which digestive system organ does nearly all nutrient absorption occur?

a. Stomach

b. Small intestine

c. Large intestine

d. Pancreas

Which of the following is not a major activity of the stomach?

a. Storage

b. HCl production

c. Nutrient absorption

d. Enzyme secretion

The human genome size is 3 billion base pairs, and the size of the baker's yeast genome, a single-celled organism, is 12 million base pairs. Therefore, the predicted genome size for another single-celled organism, an amoeba,

a. Is about the size of the human genome

b. Is about the size of the yeast genome

c. Is somewhere between the sizes of the yeast and human genomes

d. Cannot be predicted with any certainty

The energy content of fats

a. Is released by bile salts.

b. Is, per gram, twice that of carbohydrates or proteins.

c. Cannot be dissolved in water and so cannot be absorbed.

d. Is usually healthier than the energy content of carbohydrates.

Which of the following vitamins is mismatched with the disease that results from its underconsumption?

a. Vitamin B₆—Beriberi

b. Vitamin C—Scurvy

c. Vitamin A—Vision loss

d. Vitamin D—Rickets

Explain the role in nutrition of each of the following structures:

bird crop, cow rumen, and elephant cecum.

If you put the following events in the order they occur in the human digestive system, the third event in the series would be

a. Cells in gastric pits secrete protons.

b. Pepsin activates pepsinogen.

c. HCl activates pepsinogen.

d. Partially digested food enters the small intestine.

Which of the following statements is false?

a. A healthy human has enough stored fat to supply calories for several weeks.

b. An increase in leptin levels leads to an increase in appetite and weight gain.

c. The interconversion of glucose and glycogen takes place in the liver.

d. After glycogen stores are filled, excessive calories are stored as fat, regardless of their original food source.

Why is oral rehydration therapy with a solution of sodium chloride and glucose an effective treatment for dehydration?

a. The sodium and glucose decrease urine output.

b. The sodium and glucose facilitate water absorption by the small intestine.

c. The sodium and glucose help kill intestinal bacteria.

d. The sodium and glucose make the person thirsty.

Why is it necessary for healthy vegetarians to combine different plant foods or eat some eggs or milk products?

a. To make sure they obtain sufficient calories

b. To provide sufficient vitamins

c. To make sure they ingest all essential fatty acids

d. To provide all essential amino acids for protein synthesis

Why is it important that the small intestine has a much greater surface area than the stomach or esophagus?