39. Digestive System

Which food items are typical of an herbivorous diet?

Which of the following is acquired outside of an animal's diet?

Animals need two types of organic precursors from their food, __________, to serve as the raw materials for the synthesis of larger organic molecules.

A breakfast cereal advertises that it contains essential vitamins and minerals. In this context, the word essential means __________.

Which of the following are considered essential nutrients: (1) certain carbohydrates, (2) certain fatty acids, (3) certain amino acids, and/or (4) cholesterol?

In general, B vitamins function in your body as __________.

B vitamins should be consumed daily, but vitamin A can be consumed more sporadically. Why is this true?

The fat-soluble vitamins include __________.

__________ are needed in the diet as components of teeth and bone, as parts of certain enzymes, for normal muscle and nerve function, and for water balance.

An insufficient supply of chemical energy in the diet or a shortage of one or more essential nutrients results in which of the following?

Despite long days grazing on tall grasses, several of the cattle released into a new pasture have oddly shaped or broken legs and often lie down. These cattle might be suffering from __________.

Which of the following statements about nutrition and digestion is true?

Which of the following statements is true?

Which of the following animals has a gastrovascular cavity with a single opening?

Which of the following animals uses only intracellular digestion?

In vertebrates, food is moved along the length of the digestive system by __________.

Chemical digestion of carbohydrates begins in the __________ with the action of __________.

The tongue does all of the following except __________.

How is the stomach lining protected from the strongly acidic pH of its contents?

Which of the following might make the most effective anti-ulcer medication?

Which of the following statements regarding protein digestion is true?

Acid chyme __________.

In humans, most nutrient molecules are absorbed by the __________.

The liver and pancreas add their secretions to the partially digested food produced in the stomach, in the __________ of the small intestine.

The natural antacid that protects the intestines against stomach acid is produced by the __________.

Which of the following processes, structures, or conditions are properly matched?

Most digestive enzymes function in the __________.

Pepsin is an enzyme produced in the stomach that attacks proteins to break them down into smaller peptide molecules. Which of the following statements about this enzyme is true?

The lungs consist of many small air sacs and blood vessels, which greatly increase surface area and improve the transfer of substances through their walls. The structures in the digestive system most similar in function to these air sacs and capillaries are the __________.

Gallstone surgery sometimes requires that the gallbladder be removed. Patients are then advised to avoid ingesting large amounts of fat because __________.

Which of the following animals rely on symbiotic relationships with bacteria to obtain nutrients?

How would you expect the digestive system of a hawk to compare with that of a seed-eating sparrow?

Where does absorption take place in the small intestine?

Researchers provided radioactively labeled food to a dog and traced the movement of absorbed molecules. Which type of molecule moved along a path different from all the others?

The lymphatic vessels in the villi absorb and transport __________.

During some types of antibiotic treatments, patients often experience diarrhea because __________.

Symbiotic bacteria living in our large intestines provide us with __________.

What relation do indigestible plant fibers, prokaryotes, and vitamins have with the digestive system?

Which of the following is an adaptation to a carnivorous diet?

Fat digestion yields fatty acids and glycerol. Protein digestion yields amino acids. Both digestive processes a. occur inside cells in most animals. b. add a water molecule to break bonds. c. require a low pH resulting from HCl production. d. consume ATP.

Label the parts of the human digestive system below and indicate the functions of these organs and glands. a. b. c. d. e. f. g. h. i. j. k. l.

There are several key concepts introduced in this chapter: Structure correlates with function; an animal's body has a hierarchy of organization with emergent properties at each level; and complex bodies have structural adaptations that increase surface area for exchange. Label the tissue layers shown in this section of the small intestine, and describe how this diagram illustrates these three concepts.. a. Microvilli b. Mucosa c. Muscularis d. Sub-serous layer e. Serosa

Calculate and compare the caloric content of skim milk and whole milk. Per serving, skim milk contains 12 g carbohydrates, 8 g protein, and no fat; whole milk contains 12 g carbohydrates, 8 g protein, and 8 g fat.

The mammalian trachea and esophagus both connect to the a. pharynx. b. stomach. c. large intestine. d. rectum.

What is a plasmid? a. an organelle found in many bacteria and certain eukaryotes b. a circular DNA molecule that replicates independently of the main chromosome(s) c. a type of virus that has a DNA genome and infects certain types of human cells, including lung and respiratory tract tissue d. a type of virus that has an RNA genome, codes for reverse transcriptase, and inserts a cDNA copy of its genome into cells

Complete the following map summarizing the nutritional needs of animals that are met by a healthy diet. a. b. c. d. e. f. g.

Evaluate the following statements regarding digestion; select True or False for each statement. T/F Salivary amylase completes the digestion of starch into monosaccharides. T/F Pepsin digests proteins in the stomach. T/F Trypsin digests disaccharides into monosaccharides. T/F Pancreatic lipase performs the majority of chemical digestion of lipids.

In which organ does almost all enzymatic digestion of food occur? (A) stomach (B) small intestine (C) large intestine (D) pancreas

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. feed mostly on mineral substrates. filter small organisms from the soil. are bulk feeders that ingest large pieces of food. 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.

After surgical removal of the gallbladder, a person might need to limit his or her dietary intake of a. starch. b. protein. c. sugar. d. fat.

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?

A peanut butter and jelly sandwich contains carbohydrates, proteins, and fats. Describe what happens to the sandwich when you eat it. Discuss ingestion, digestion, absorption, and elimination.

Use the Nutrition Facts label to the right to answer these questions: Each gram of fat supplies 9 Calories. Based on the grams of saturated fat and its % Daily Value, calculate the upper limit of saturated fat (in grams and Calories) that an individual on a 2,000-Calorie/day diet should consume.

Use the Nutrition Facts label to the right to answer these questions: Is this product a good source of vitamin D and calcium? Explain.

Use the Nutrition Facts label to the right to answer these questions: What percentage of the recommended daily value of fat is found in a 1-cup serving?

How might our craving for fatty foods, which is helping to fuel the obesity crisis, have evolved through natural selection?

Among vertebrates, the large intestine exists only in lineages that are primarily terrestrial (amphibians, reptiles, and mammals). Propose a hypothesis to explain this observation.

One common piece of dieting advice is to replace energy-dense food with nutrient-dense food. What does this mean?

Minnows are mainly carnivorous, eating insects and other small animals. However, herbivory has evolved independently in minnows several times. What changes in digestive structure and function are associated with the evolution of herbivory? Like cichlids, minnows use their pharyngeal jaws to process food. Suggest some possible structural differences between the teeth on the pharyngeal jaws of carnivorous and herbivorous minnows.

The media report numerous claims and counterclaims about the benefits and dangers of certain foods, dietary supplements, and diets. Have you modified your eating habits on the basis of nutritional information disseminated by the media? Why or why not? How should we evaluate whether such nutritional claims are valid?

Minnows are mainly carnivorous, eating insects and other small animals. However, herbivory has evolved independently in minnows several times. What changes in digestive structure and function are associated with the evolution of herbivory? Which of the following is true of the digestive tracts of minnows? a. They are incomplete but have both a mouth and an anus. b. They are complete, facilitating compartmentalization of digestion in different organs. c. They are incomplete, with no accessory organs. d. They are complete and include a large gastrovascular cavity.

It is estimated that 15% of Americans do not always have access to enough food. Worldwide, more than 1 billion people go to bed hungry most nights, and millions of people have starved to death in recent decades. In some cases, war, poor crop yields, and disease epidemics strip people of food. Many say instead that it is not inadequate food production but unequal food ­distribution that causes food shortages. What responsibility do nations have for feeding their citizens? For feeding the people of other countries? What do you think you can do to lessen world hunger?

Minnows are mainly carnivorous, eating insects and other small animals. However, herbivory has evolved independently in minnows several times. What changes in digestive structure and function are associated with the evolution of herbivory? Researchers compared the relative gut length—the length of the digestive tract divided by body length—in four species of herbivorous minnows and four species of carnivorous minnows. The results are shown in the graph provided here. Based on these data, what conclusion can you draw about the relationship between diet and gut length?

SCIENTIFIC THINKING Consider the relationship between ­correlation and causation with respect to some pairs of human traits. For example, are freckles and red hair correlated? Is there causation? How does this concept relate to the study of human nutrition? Can you name examples of correlation in humans with respect to obesity? Explain each answer.

Minnows are mainly carnivorous, eating insects and other small animals. However, herbivory has evolved independently in minnows several times. What changes in digestive structure and function are associated with the evolution of herbivory? Suggest a function of the difference in relative gut lengths of herbivorous and carnivorous minnows.

Minnows are mainly carnivorous, eating insects and other small animals. However, herbivory has evolved independently in minnows several times. What changes in digestive structure and function are associated with the evolution of herbivory? Which minnows, herbivorous or carnivorous, should exhibit higher cellulase activity in the gut? Explain.

Minnows are mainly carnivorous, eating insects and other small animals. However, herbivory has evolved independently in minnows several times. What changes in digestive structure and function are associated with the evolution of herbivory? Why did the researchers compare relative gut length instead of absolute gut length?