Mastering Bio - Ch. 41 Animal Digestion

Your small intestine can absorb ____ without any prior digestion into smaller molecules.

D. fructose (Fructose is a monosaccharide, and monosaccharides can be absorbed without having to be broken down into smaller units.)

Now calculate the surface area of the hemispherical top of the microvillus rod. Use 3.14 for π. Enter your answer rounded to two decimal places.

0.02 The surface area of a sphere = 4 × π × r2 SA of the half sphere = (4 × π × r2) / 2 If the diameter of the sphere is 0.1 μm, then the radius is 0.05 μm. SA of the top of the microvillus = 4 × 3.14 × (0.05)2 / 2 = 0.0157 μm2 or 0.02 μm2 (rounded to two decimal places)

A single microvillus is a rod-like structure that is 1.0 μm in height. It has a hemispherical top approximately 0.1 μm in diameter. Calculate the surface area of the cylinder that forms the "sides" of the microvillus rod. Use 3.14 for π. Enter your answer rounded to two decimal places.

0.30 The surface area of the cylinder "sides" = 2 π r h, where r is the radius and h is the height (total height minus the height of the hemispherical top). SA = 2 x 3.14 x 0.05 μm x 0.95 μm = 0.2983 μm2 or 0.30 μm2 (rounded to two decimal places)

Now use your answers from Parts A and B to calculate the entire surface area of one microvillus (in μm2). Enter your answer rounded to two decimal places.

0.32 The microvillus structure consists of two geometric shapes: the top, which is a half sphere, and the "sides," which is a rectangle rolled into a cylinder. Total surface area of a microvillus = 0.02 (SA of top) + 0.30 (SA of "sides") = 0.32 μm2

Which acid does the stomach of all vertebrates secrete?

A. hydrochloric acid

What is the percent increase in absorptive surface of the intestine due to the microvilli? Enter your answer as a whole number (in %).

540 In this problem, you are asked to determine the percent increase in surface area due to microvilli. If the absorptive surface without microvilli is 1 cm2 and the absorptive surface with microvilli is 6.4 cm2, there is an increase of 5.4 cm2. (5.4 cm2 / 1 cm2 ) x 100 = 540% An 540% increase means that the small intestine with microvilli has 5.4 times more absorptive surface area than it would have without microvilli.

Suppose there are 2.0 x 109 microvilli per cm2 of intestinal epithelium. Calculate the total surface area of the microvilli in one cm2 of intestinal epithelium. Enter your answer to one decimal place. (Note that the units are cm2, not μm2.)

6.4 If the SA of one microvillus is 0.32 μm2, then the SA of 2.0 x 109 microvilli = 0.64 x 109 μm2= 6.4 x 108 μm2 To convert the answer into cm2 , recall that 1 cm = 10,000 μm. So 1 cm2 = (10,000)2 μm2. (6.4 x 108) μm2 x 1 cm2 / 108 μm2 = 6.4 cm2

Part C Choose the correct statement from the list below.

A. Free fatty acid absorption occurs in the small intestine. (Fat digestion is not complete until pancreatic lipases finalize fat digestion in the small intestine.)

Why is energy needed for the absorption of glucose in the digestive tract?

A. Na+/K+-ATPase enzymes use ATP to create a sodium gradient which drives sodium-glucose cotransport into intestinal epithelial cells. (ATP must be expended to create a sodium gradient across the cell membrane and permit glucose absorption against its concentration gradient.)

In humans, most digestion occurs in what structure?

A. Small intestine {This section of the digestive track receives digestive enzymes from the pancreas and bile from the liver (by way of the gall bladder).}

Once digestion of skim and whole milk begins in the duodenum, the hormone cholecystokinin is released into the bloodstream. A satiety center in the brain detects CCK. Which type of milk is likely to produce a longer lasting sense of satiety?

A. Whole milk will give a greater sense of satiety because both proteins and fats stimulate CCK release. (Proteins are hydrolyzed to amino acids. Fats are hydrolyzed to mono- and diglycerides and fatty acids. Amino acids and fatty acids both stimulate cells in the duodenum to release CCK. Whole milk has 16 g of protein + fat, while skim milk has only 8 g protein. Drinking whole milk will stimulate either a greater or more sustained release of CCK.)

Which of the following make up the gastric juice?

A. pepsin , C. hydrochloric acid , & D. water (Water is the primary component of many secretions, including gastric juice.)

Which of these enzymes begins the breakdown of starch?

D. amylase (The digestion of starches, such as amylose, begins with the amylase secreted by the salivary glands.)

Part B Which statement if TRUE?

B. Carbohydrate digestion begins in the mouth with salivary amylase. (Carbohydrate digestion begins with the action of salivary amylase in the mouth)

What are the effects of a molecule that blocks the sodium-glucose co-transporter in the small intestine?

B. Increased feces production due to the passing of unabsorbed glucose (The reduction in glucose absorption would have this effect.)

What is the relationship between diet and the structure of the digestive tract? 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? Part A Part complete 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 that follows (*** means P<0.001). Based on these data, what conclusion can you draw about the relationship between diet and gut length?

B. The relative gut length of herbivorous minnows is greater than that of carnivorous minnows.

Chemical digestion of carbohydrates and lipids begins in the ____________, while chemical digestion of proteins begins in the _____________.

B. mouth; stomach (Salivary amylase and lingual lipase attack carbohydrates and lipids in the mouth, while pepsin begins protein digestion in the stomach.)

Part A Choose the correct statement from the list below.

C. Proteins are digested to individual amino acids before being absorbed in the small intestine. (The building blocks of proteins are amino acids.)

Protein digestion begins in the _____.

C. Stomach (The secretion of gastric juice by the stomach begins the digestion of proteins.)

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

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

In mammals, how and where are carbohydrates digested?

C. by amylases in the mouth and small intestine

Starch is a type of _____.

C. polysaccharide & F. carbohydrate {Starch is a carbohydrate composed of many monomers (many monosaccharide units).}

Why do many acid reflux drugs contain proton pump inhibitors?

D. Blocking the pumps reduces the acidity of the stomach by reducing the number of protons pumped from the parietal cells into the lumen. (Without this active transport, the protons made in the parietal cells would not be concentrated in the lumen.)

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

D. Nutrient absorption occurs in the small intestine and the rate of absorption increases with surface area.

Why is the surface area of the small intestine so high compared to the stomach?

D. To better absorb nutrients

When digested, proteins are broken down into _____.

D. amino acids (Proteins are composed of amino acids.)

_____ is secreted by the _____ and acts to emulsify _____ in the lumen of the _____.

E. Bile ... liver ... fats ... small intestine (Bile, produced by the liver and stored by the gall bladder, emulsifies fats in the small intestine. The smaller fat droplets present a greater surface area for the action of lipases)

When digested, fats are broken down into _____.

E. both glycerol and fatty acids (Fats are composed of glycerol and fatty acids.)

Among vertebrates, the large intestine exists only in lineages that are primarily terrestrial (amphibians, reptiles, and mammals). Propose a hypothesis to explain this observation. Drag the terms on the left to the appropriate blanks on the right to complete the sentences.

TERRESTRIAL vertebrates are exposed to INCREASED risk of water loss, and water reabsorption is the primary function of the large intestine. AQUATICE vertebrates DO NOT NEED to reabsorb large amounts of water from their feces.

What is the relationship between diet and the structure of the digestive tract? 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? Part A Part complete 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 that follows (*** means P<0.001 Suggest a function of the difference in relative gut lengths of herbivorous and carnivorous minnows. Drag the terms on the left to the appropriate blanks on the right to complete the sentences.

The LONGER gastrointestinal tracts of HERBIVORES allow more time to digest PLANTS AND ALGAE, and provide more area to house symbiotic microbes that aid in the digestion of VEGETATION.

What is the relationship between diet and the structure of the digestive tract? 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? Part A Part complete 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 that follows (*** means P<0.001 ). Why did the researchers compare relative gut length instead of absolute gut length? Drag the terms on the left to the appropriate blanks on the right to complete the sentences.

The minnows likely VARIED in overall body size, so LARGER fish could have had longer guts regardless of diet. Dividing gut length by body length allowed the researchers to rule out differences in gut length due solely to differences in body size. Knowledge about relative gut length makes the researchers ABLE TO consider if the fish is carnivorous or herbivorous.

Calculate 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. Carbohydrates and proteins both contain 4 kcal energy/g, while fat contains 9 kcal/g. Express your answers as integers separated by a comma.

skim milk, whole milk 80, 152 kcal