Biology - Chapter 21 Nutrition and Digestion Activity

Now calculate the surface area of the hemispherical top of the microvillus rod. Use 3.14 for π.π. For help, review this tutorial: Calculating the Surface Area of a Sphere.(Remember that the top of the microvillus is only half of a sphere.) 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 μμm, then the radius is 0.05 μμm. SA of the top of the microvillus = 4 × 3.14 × (0.05)2/ 2 = 0.0157μμm2or0.02μμm2(rounded to two decimal places)

A single microvillus is a rod-like structure that is 1.0 μμm in height. It has a hemispherical top approximately 0.1 μμm in diameter. Calculate the surface area of the cylinder that forms the "sides" of the microvillus rod. Use 3.14 for π.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 μμm x 0.95 μμm = 0.2983 μμm2 or 0.30 μμm2 (rounded to two decimal places)

Now use your answers from Parts A and B to calculate the entire surface area of one microvillus (in μμm2). (Remember that a microvillus is a projection of the intestinal surface, so there is no "bottom" surface.) 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 μμm2

Can you match the following terms about diet categories and feeding mechanisms to their descriptions?

1. Animals that mostly eat other animals fit into the dietary category called carnivores. 2. Animals that mostly eat plants or algae fit into the dietary category called herbivores. 3. Lemurs and humans would both fit into the dietary category called omnivores. 4. Many aquatic animals, from delicate tube worms to giant humpback whales, filter small food items from the water and are called filter (or suspension) feeders. 5. Animals that live in or on their food source and eat their way through their food are called substrate feeders. 6. Animals that suck nutrient-rich liquids from an animal or plant host are called fluid feeders. 7. Many animals are bulk feeders, ingesting their food whole or by the piece.

Can you match the following terms about nutrient absorption and processing to their descriptions?

1. During the process of digestion, large food molecules are broken down into small components that can be absorbed into cells that form the lining of the small intestine. 2. Circular folds, villi, and microvilli--tiny projections from the surfaces of cells--increase the surface area for absorption. 3. After moving into cells of the intestinal lining, fatty acids and glycerol are recombined into fats, coated with proteins, and transported into lymph vessels, which eventually empty into large veins. 4. Sugars and amino acids pass from the intestinal epithelium and into blood capillaries. 5. The nutrient-laden blood from the intestines is carried in the hepatic portal vein to the liver. 6. The liver removes excess glucose from the blood and stores it as glycogen. 7. The liver also converts nutrients to other essential substances, such as plasma proteins, cholesterol, and fats.

You travel to England for a vacation. Which of the following people you meet is most likely to be a vegan?

27-year-old woman

How many more calories would a 240-pound man need to consume than a 170-pound man to maintain a constant weight?

300 calories

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 μμm2.)

6.4 If the SA of one microvillus is 0.32 μμm2, then the SA of 2.0 x 109 microvilli = 0.64 x 109 μμm2= 6.4 x 108 μμm2 To convert the answer into cm2 , recall that 1 cm = 10,000 μμm. So 1 cm2 = (10,000)2 μμm2. (6.4 x 108) μμm2 x 1 cm2 / 108 μμm2 = 6.4 cm2

The key nutrients absorbed by the small intestine are sugars, amino acids, and fats. How is each nutrient transported to the liver?

Sugars and amino acids enter the circulation through capillaries within the villi and travel through blood vessels to the liver. Fats enter lymph vessels and travel through the lymphatic system before entering the circulation and traveling to the liver via blood vessels.

The epithelial tissue that lines the lumen of the small intestine is extensively folded into large circular folds. These folds have finger-like projections called villi. The epithelial cells on the surface of each villus have microscopic, finger-like projections called microvilli. Which of the following statements about the lining of the intestinal lumen are true?

The structure of the inner lining of the intestine is an example of structure-function correlation. True. The folds, villi, and microvilli greatly increase the rate of movement of food through the small intestine. False. The structure of the small intestine is an adaptation that is a product of natural selection. True. The folds, villi, and microvilli greatly increase the surface area of the lining and, as a result, enhance the ability of the small intestine to absorb nutrients. True. The folds, villi, and microvilli help break up the food into smaller and smaller pieces. False.

Can you complete this paragraph that summarizes key concepts about human nutrition? Match the words in the left column to the appropriate blanks in the sentences on the right.

Your diet provides fuel for ATP production, organic molecules as raw materials to build your own molecules, and essential nutrients − substances you require but cannot make yourself. The essential amino acids must be obtained from your diet, either by eating meat, eggs, or milk, or by consuming a variety of plant proteins. One of the essential fatty acids is needed to make membrane phospholipids. Organic nutrients called vitamins are required in very small amounts. Many of the B vitamins function as coenzymes; vitamin C is required for the production of connective tissue; and vitamins A, D, E, and K are fat-soluble. Inorganic nutrients called minerals function in various roles such as bone formation, nerve and muscle function, and enzyme cofactors.

When it comes to nutrition, which of the following children is most likely to be considered 'wasted'?

a child that is tall and thin for their age; "Globally, 149 million children under five are stunted, meaning they have low height for their age, and almost 50 million are wasted, with low weight to height ratio. Being too thin for their height can be lethal for children. Most cases, Unicef said, are in Asia, where wasting affects more than one in seven children under five."

In which of the following places are doctors likely to see the highest percentage of young people dying of cirrhosis?

a community with a large percentage of Native Americans

'If They're Not Eating Any Vegetables, You Panic': The Families Raising Vegan Children (The Guardian, 11/24/2018) Which of the following is true?

a vegan tends to eat a more exclusive diet than a vegetarian

Why should we not view lactose intolerance as a disease in adult humans?

adult humans did not consume dairy products until fairly recently in our evolutionary history

Which of the following is true regarding food labels in the United States?

all ingredients must be listed

When digested, proteins are broken down into _____.

amino acids; proteins are composed of amino acids

Which of these enzymes begins the breakdown of starch?

amylase; the digestion of starches, such as amylose, begins with the amylase secreted by the salivary glands

Which of the following people is most likely to suffer from cirrhosis?

an obese man with an alcohol problem

When should a lactase supplement be taken in order to be most effective, and why?

at the same time the dairy product is consumed, so that the lactase will be in contact with the lactose

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

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

Which of the following appears most likely to be true?

binge drinking increases the risk of cirrhosis in young people

When digested, fats are broken down into _____.

both glycerol and fatty acids; fats are composed of glycerol and fatty acids

You decide to eat healthier. When it comes to fat and the food panel, which of the following should be your goal?

consume unsaturated fats, while avoiding saturated fats trans fats

Which of the following would likely be most beneficial when it comes to children's nutrition?

encouraging mothers to breastfeed

Your small intestine can absorb ____ without their being further digested.

fructoses; fructose is a monosaccharide, and monosaccharides can be absorbed without having to be broken down into smaller units

Your friend is a vegan. Which of the following would be best for her to have to help ensure that she is absorbing iron?

glass of orange juice

You are a doctor seeing a patient. Which of the following would be most likely to lead you to think he has a problem with his liver?

he has a yellow hue

What acid is responsible for stomach acidity?

hydrochloric acid; hydrochloric acid, secreted by the stomach, is responsible for the acidity of the stomach

Which two statements about basal metabolic rate are true?

if all other factors are identical, a person who weighs more will have a higher BMR than a person who weighs less basal metabolic rate includes the energy consumed by the body during cellular respiration

Which of the following are you least likely to learn about a product when reading the Nutrition Facts panel?

if the ingredients are genetically modified

In which country would you most likely find a higher incidence of lactase persistence?

in a Scandinavian country where people historically raised dairy cattle and made cheese

Your aunt is a pediatrician. Because of diet, which of the following can she expect to see?

increasing cases of Type II diabetes

Your friend has a dairy allergy. Which of the following on a product's label would be best for you to review to determine if it is safe for her to consume?

ingredient list

Why is the enzyme lactase necessary to digest dairy products?

lactase breaks down lactose into smaller molecules that can be absorbed by the cells that line the small intestine

Most people are lactose intolerant as adults, but nearly everyone produces sufficient lactase as an infant. However, in some cases, genetic mutations can occur that make an infant lactose intolerant. From an evolutionary perspective -- over thousands of years -- why would lactose intolerance in infants be very rare in the population?

lactose intolerant infants could not digest breast milk and therefore usually died, never having the chance to pass the mutation on to their children

Starch can be broken down into the disaccharide known as _____.

maltose; starch is composed of many maltose units

Chyme enters the small intestine from the stomach. At this point, _____.

mechanical digestion is essentially complete, but the other processes are ongoing or have not yet begun

'Failing' Food System Leaves Millions of Children Malnourished or Overweight (The Guardian, 10/15/2019) If trends continue, which of the following will occur?

obesity and malnutrition will increase in children worldwide

Most mechanical processing of food occurs in the _____.

oral cavity and stomach

Which lists the major segments of the alimentary canal in the correct order?

oral cavity, esophagus, stomach, small intestine, large intestine

Starch is a type of _____.

polysaccharide; starch is a carbohydrate composed of many monomers (many monosaccharide units)

Absorption of food monomers occurs primarily in the _____.

small intestine

Who is likely to be the most frustrated with the new food panel as compared to the old food panel?

someone with a Vitamin A deficiency

Your three-year-old nephew is lactose intolerant and thus cannot drink cow's milk. Which of the following would be the best substitute for protein?

soy milk

Several important enzymes and other secretions aid in digestion as food moves down the alimentary canal, as follows: in the oral cavity, salivary amylase helps break down _____; in the stomach, pepsin helps break down _____; and in the small intestine, bile helps break down _____.

starches; proteins; fats and oils

Protein digestion begins in the _____.

stomach; the secretion of gastric juice by the stomach begins the digestion of proteins

What is the function of the muscle layers in the wall of the small intestine?

the muscles are responsible for the movement of food through the small intestine by peristalsis; waves of muscle contractions that move along the length of the small intestine propel the food through the lumen of the small intestine

Assuming the United States is similar to Britain, which of the following is true?

the number of vegans is increasing

How do lactase supplements help people who are lactose intolerant?

the supplements provide the enzyme that breaks down the lactose in dairy products

You are a dietician studying food deserts in the United States. Which of the following is true?

they are more abundant in poor communities

Lactose intolerance in infants is more common in the population today than it was a hundred years ago. Why?

today there are alternatives to breast milk, such as lactose-free formula and soy milk, so lactose intolerant infants can survive

What is the main component of gastric juice?

water; water is the primary component of many secretions, including gastric juice

You are a gastroenterologist seeing a 37-year-old patient with alcohol-related cirrhosis. Which of the following is true?

your patient may be able to reverse the disease if she quits drinking