小hapter 41 袪omework

25 July 2022
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question
Sort the vitamins according to whether they are water soluble or fat soluble. Sort the items into the appropriate bin.
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water soluble: vitamin c, vitamin b1 fat soluble: vitamin k, vitamin e, vitamin d
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The __________________ act as coenzymes in the body. They do not stay bonded to only one enzyme, but are used over and over again by different enzymes.
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water-soluble vitamins
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________________ is involved in the formation of hydroxyproline and hydroxylysine, which are important amino acids and part of the collagen that forms the connective tissues. Lack of this vitamin causes scurvy, which can be prevented with citrus and other fruits.
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vitamin c
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__________________ is absorbed from some foods like carrots in the form of carotene. The vitamin accumulates in the rods and cones of the eyes and plays a role in vision.
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vitamin a
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__________________ is a vitamin that is used in reactions that transfer single-carbon units. The vitamin also helps reduce the risk of birth defects such as spina bifida and cleft lip. Women of child-bearing age should consume the recommended amount of this vitamin.
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folic acid
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The ____________________ are not involved as coenzymes. But they are still essential in our diet, and they are involved in important processes such as vision, bone formation, protection from oxidation, and blood clotting.
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fat-soluble vitamins
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Choose the list that presents the four stages of food processing in the order in which they naturally occur.
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ingestion 鈫 digestion 鈫 absorption 鈫 elimination
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Which structure is not part of the alimentary canal?
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Salivary glands.
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Which process is not required for an animal to obtain energy from food?
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Excretion.
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True or false? One advantage of having a tube-like digestive tract is that digestion of all compounds can take place simultaneously down the tract.
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False.
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True or False? The liver is a component of the alimentary canal.
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False.
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Choose the correct statement from the list below.
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Proteins that are consumed in the diet are absorbed as individual amino acids following digestion.
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Choose the correct statement from the list below.
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Carbohydrate digestion begins in the mouth with salivary amylase.
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Choose the correct statement from the list below.
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Free fatty acid absorption occurs in the small intestine.
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Which of the following is an example of positive feedback in the lumen of the stomach?
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Pepsin digests molecules of pepsinogen, producing more pepsin.
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How do hydrogen ions (H+) and chloride ions (Cl-) get into the lumen of the stomach?
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H+ is actively transported from parietal cells into the lumen, while Cl- diffuses from parietal cells into the lumen.
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A researcher added a mixture of animal proteins to a physiological buffer solution (pH 7.4) in a test tube incubated at 37掳C. The researcher then added purified pepsin to the mixture, but even after several hours, the proteins were not digested. Which of the following would explain this result?
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The pH was too high.
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What is one function of mucus in the lumen of the stomach?
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It protects the epithelium from being digested by gastric juice.
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The epithelium that lines the stomach has many deep infoldings, or pits. In what way do these pits function as glands?
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They secrete gastric juice into the main chamber of the stomach.
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A fat molecule is composed of two types of smaller molecules, including only one molecule of _______________.
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glycerol
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A fat molecule also includes one, two, or three _____________ molecules.
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fatty acid
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A fat molecule with only one fatty acid is called a ______________.
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monoglyceride
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A fat molecule with three fatty acids is called a triacylglycerol, or a _______________.
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triglyeride
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A fatty acid includes a carboxyl group (-COOH) at one end as well as a long _____________________.
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hydrocarbon chain
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The hydrocarbon chains found in fats store a lot of energy. They also make fats __________________, or insoluble in water.
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hydrophobic
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Drag each statement into the appropriate bin depending on whether the event occurs in the lumen of the small intestine, in a small intestine epithelial cell, or in a lacteal.
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lumen of small intestine: -Lipase breaks triglycerides down into monoglycerides and fatty acids. epithelial cell: -Monoglycerides and fatty acids are reassembled to form triglycerides. -Triglycerides are coated with phospholipids, cholesterol, and proteins to form chylomicrons. -Chylomicrons leave this structure by exocytosis. lacteal: -Chylomicrons are transported in this structure to veins. -This structure contains lymph.
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The lower esophageal sphincter surrounds the upper opening into the stomach. If this sphincter failed to properly constrict, there might be a problem with _____.
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regurgitation of acidic stomach contents into the esophagus, commonly called "heartburn"
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Different types of food are eaten by various groups of animals, but it is usually true that _____.
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cellulose digestion in ruminant mammals occurs before the ingested foods reach the small intestine
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Locate the pie chart showing the microbiome of a healthy adult's intestinal tract. Which statement best represents the bacterial community composition of a healthy adult's intestinal tract?
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Firmicutes are the most abundant bacteria in the intestinal tract of healthy adults, followed by Bacteroidetes and a small amount of Actinobacteria and Proteobacteria.
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Which statement best represents the bacterial community composition of a healthy adult's stomach?
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Actinobacteria are the most abundant bacteria in the stomach of healthy adults, followed by Firmicutes, and roughly equal amounts of Bacteroidetes and Proteobacteria.
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Compare the relative abundance of Actinobacteria in the microbiome of a healthy adult's intestinal tract to that of a healthy adult's stomach. Which statement best represents the relative abundance of Actinobacteria in each?
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Actinobacteria are abundant in the stomach, but rare in the intestinal tract of healthy adults.
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Secretin stimulates the _____ to secrete _____.
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pancreas ... bicarbonate
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Cholecystokinin (CCK) stimulates the _____ to secrete _____.
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pancreas ... pancreatic enzymes
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The acidity of the stomach contents triggers the small intestine to secrete a hormone known as _____.
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secretin
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The presence of fatty acids and amino acids in the chyme from the stomach triggers the small intestine to secrete a hormone known as _____.
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cholecystokinin, or CCK
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Bile is produced by the _____ and stored by the _____ until it is secreted into the small intestine.
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liver ... gall bladder
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Among humans, increased interest in food intake normally occurs _____.
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via chemical signals released when the stomach is empty
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Proteins consist of amino acids linked to
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other amino acids
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Which of the following is hydrophobic and therefore insoluble in water?
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lipid
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Animals obtain the energy they need for growth by
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breaking down organic molecules
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To survive, all animals must _____.
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balance consumption of food with use and storage of nutrients
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The "essential nutrients" for proper human nutrition include _____.
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calcium, sodium, potassium, and other minerals
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Birth defects of the neural tube in humans _____.
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are reduced from about 6% without folic acid supplements in the periconception interval to about 1% when the supplements were taken
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The gastrovascular cavity differs from the alimentary canal in that only the gastrovascular cavity _____.
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has only a single opening
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When digested, proteins are broken down into _____.
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amino acids
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When digested, fats are broken down into _____.
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both glycerol and fatty acids
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Starch is a type of _____.
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polysaccharide
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Your small intestine can absorb ____ without their being further digested.
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fructoses
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Which of these enzymes begins the breakdown of starch?
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amylase
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Starch can be broken down into the disaccharide known as _____.
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maltose
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Protein digestion begins in the _____.
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stomach
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What is the main component of gastric juice?
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water
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_____ is secreted by the _____ and acts to emulsify _____ in the _____.
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Bile ... liver ... fats ... small intestine
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What acid is responsible for stomach acidity?
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hydrochloric acid
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Choose the correct anatomical sequence that presents the order in which food in the digestive system passes through.
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pharynx 鈫 esophagus 鈫 stomach 鈫 small intestine 鈫 large intestine
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For ingested foods, the first opportunity for enzymatic digestion occurs in the _____.
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mouth
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Fat digestion yields fatty acids and glycerol, whereas protein digestion yields amino acids. Both digestive processes __________.
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add a water molecule to break bonds
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The mammalian trachea and esophagus both connect to the
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pharynx.
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Which of the following organs is incorrectly paired with its function?
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large intestine-bile production
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Which of the following is not a major activity of the stomach?
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nutrient absorption
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If you put the following events in the order they occur in the human digestive system, the third event in the series would be:
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Pepsin activates pepsinogen.
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After surgical removal of an infected gallbladder, a person must be especially careful to restrict dietary intake of
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fat.
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If you were to jog 1 km a few hours after lunch, which stored fuel would you probably tap?
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muscle and liver glycogen
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Animals that migrate great distances would obtain the greatest energetic benefit of storing chemical energy as _____.
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fats
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The process by which digested dietary substances cross cell membranes to be used by the body is known as ________.
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absorption
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Mechanical digestion, the process of breaking down large chunks of food into smaller pieces, is important because smaller pieces of food ________.
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have more surface area for chemical digestion than do larger pieces of food
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Examine the digestive system structures in the figure. The agents that help emulsify fats are produced in location ________.
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9
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Examine the digestive system structures in the figure. The highest rate of nutrient absorption occurs at location ________.
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4
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Examine the digestive system structures in the figure. Most of the digestion of fats occurs in structure(s) ________.
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4
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Which of the following organs is correctly paired with its function?
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small intestine: polysaccharide digestion
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The function of chylomicrons is to ________.
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transport lipids from the intestine to other organs
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What is the importance of the mucus that are released by salivary glands?
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They are glycoproteins that make food slippery enough to slide easily through the esophagus.
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Why do the cells of the digestive system secrete proteolytic enzymes, such as pepsin, in their inactive forms?
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These proteolytic enzymes, in active form, would digest the very tissues that synthesize them
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The digestion of ________ begins in the stomach.
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protein
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Nutrient-rich blood from the intestine is carried through the ________ to the liver.
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hepatic portal vein
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Pepsinogen is converted to its active form in the stomach by ________.
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HCl
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The large surface area in the gut directly facilitates _____.
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absorption
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Among mammals, it is generally true that _____.
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the epiglottis prevents swallowed food from entering the trachea
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Stomach cells are moderately well adapted to the acidity and protein-digesting activities in the stomach by having _____.
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a thick, mucous secretion and active mitosis of epithelial cells
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Upon activation by stomach acidity, the secretions of the parietal cells _____.
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initiate the chemical digestion of protein in the stomach
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Over-the-counter medications for acid reflux or heartburn block the production of stomach acid. Which of the following cells are directly affected by this medication?
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parietal cells
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The bile salts _____.
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emulsify fats in the duodenum
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The absorption of fats differs from that of carbohydrates in that _____.
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most absorbed fat first enters the lymphatic system, whereas carbohydrates directly enter the blood
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After surgical removal of an infected gallbladder, a person must be especially careful to restrict dietary intake of _____.
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fat
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If you place a small piece of a cracker on your tongue, what would you expect to happen?
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Salivary amylase degrades the starch from the cracker into maltose.
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Animals cannot produce enzymes to digest cellulose, yet many termite species consume cellulose from plant material as a main part of their diet. How do termites access the nutrients contained in cellulose?
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Mutualistic bacteria in the hindgut of the termite digest the cellulose into sugars.
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What benefit is gained by intestinal bacteria living in a mutualistic relationship with an animal?
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The bacteria are provided with a regular source of nutrients.
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When used appropriately, antibiotic treatment can effectively reduce bacteria populations and help fight infections. However, antibiotic treatments can have unintended effects. What is one concern when using antibiotics?
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Antibiotics may also kill the beneficial bacteria of the microbiome, thereby disrupting digestive health.
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Cattle are able to survive on a diet consisting almost entirely of plant material because cattle _____.
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have cellulose-digesting, symbiotic microorganisms in chambers of their stomachs
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In a healthy person, after a carbohydrate-rich meal, the production of ________ will increase, causing the uptake of ________ from the blood into liver cells.
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insulin; glucose
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A fasting animal whose energy needs exceed those provided in its diet will draw on its stored resources in which order?
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liver glycogen, then muscle glycogen, then fat
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If you were to jog one kilometer a few hours after lunch, which stored fuel would you probably tap?
answer
liver glycogen and muscle glycogen
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When the digestion and absorption of organic carbohydrates results in more energy-rich molecules than are immediately required by an animal, the excess is _____.
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stored as glycogen in the liver and muscles