Animal nutrition practice questions PDF

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Animal Nutrition – Practice questions Organized by learning goal. These questions are examples of the kinds of questions you will see on the midterm or final. The more challenging questions are marked with an asterisk (*). Learning Objective 1: Explain how carbohydrates are digested into their component nutrients 1. Why would increases in the number of copies of the amylase gene in the genome increase the ability to digest carbohydrates? 2. Explain why humans are unable to digest cellulose. 3. Compare foregut and hindgut fermenters 4. Explain why small animals that are hindgut fermenters often each their feces (“poop”) 5. * Antibiotics can be dangerous for rabbits (which are hindgut fermenters with a large caecum), especially when given orally (via the mouth). If you treat an animal such as a rabbit with oral antibiotics, what would you expect to happen to the digestion and absorption of nutrients, and why? 6. What is a rumen? Explain its role in the digestion of the types of diets consumed by ruminants. 7. Plant cell walls contain cellulose, which makes up the bulk of the macronutrients in plant material. Considering that all vertebrates lack the enzymes to digest cellulose, how do so many of them manage to survive on a plant diet? 8. *** Foregut fermentation has evolved several times independently in herbivorous mammals. In addition to being found in the Artiodactyla (cattle, sheep, deer, giraffes and antelope) it is also seen in sloths, colobine monkeys, some rodents and two families of marsupials. In the artiodactyl ruminants, digestion results in the production of large amounts of methane, whereas digestion in kangaroos produces very little methane. Suggest a hypothesis that could account for this observation. 9. **Imagine two herbivorous diets. One diet consists entirely of grass, which has cell walls that are very high in cellulose and lignin, while the other diet consists mostly of grains, which have less cellulose and more glucose and fat. Which diet would be more likely for a ruminant herbivore and which diet would be more likely for a nonruminant herbivore? Explain your answer.

Learning Objective 2: Explain how proteins are digested and compare this to carbohydrate digestion 1. How does the low pH of the stomach aid in the digestion of proteins? 2. Explain the relationship between stomach acid and pepsinogen in the digestion of proteins 3. Why does the first step of protein digestion occur in the stomach, not in the mouth? 4. Why would a person with a weak esophageal sphincter on the stomach complain of “heartburn”? 5. How are the tissues of the stomach protected from the acidic stomach fluid? 6. How is the small intestine protected from the acidic fluid coming from the stomach? 7. Explain how proteins are digested in the stomach.

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Animal Nutrition – Practice questions Organized by learning goal. 8. The image below shows the digestive tracts of two mammals. One is a carnivore and one is an herbivore. Which is which? Justify your answer.

Learning Objective 3: Explain the role and regulation of acid secretion in the stomach 1. Erica had a bad case of stomach flu that caused her to vomit for three days. She subsequently began to complain of pain in her chest, and was concerned that she might be having a heart attack. She went to the doctor, who diagnosed the condition as esophagitis (an irritation of the esophagus). What caused the esophagitis? Explain your answer. 2. *When parietal cells secrete protons into the stomach, what would you predict would happen to the pH of the blood? Justify your answer. 3. What stimuli control acid secretion in the stomach? 4. * Patients with tumours in the gastrin secreting cells of the stomach sometimes have uncontrolled gastrin secretion and thus high levels of circulating gastrin in the blood. These tumours can lead to stomach ulcers (a break or sore in the lining of the stomach that does not heal). Explain why these tumours might cause ulcers. 5. *The graph below shows stomach pH in a human. On the graph, indicate when you think gastrin levels in the blood will be greatest. Justify your answer.

6. * Bulemia is a condition in which the patient induces vomiting following meals. Bulemia is associated with an increase in the pH of the blood. Based on what you know about acid secretion in the stomach, why might this occur? Learning Objective 4: Predict what would happen to digestion if any step of stomach acid secretion is altered 1. Proton pump inhibitors are drugs that are widely prescribed to treat conditions such as heart burn and stomach ulcers. These drugs irreversibly bind to and inhibit the proton ATPase in parietal cells. Explain why these drugs are prescribed for these conditions. 2. * Proton pump inhibitors are drugs that are widely prescribed to treat conditions such as heart burn and stomach ulcers. These drugs irreversibly bind to and inhibit the proton ATPase in parietal cells. What effect would these drugs have on protein digestion?

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Animal Nutrition – Practice questions Organized by learning goal. 3. * Acetazolamide is a drug that inhibits carbonic anhydrase. What effect would acetazolamide have on the digestion of proteins in the stomach? Justify your answer. 4. * When parietal cells secrete protons into the stomach, what would you predict would happen to the pH of the blood? Explain your answer. Learning Objective 5: Explain how nutrients are taken up in the small intestine 1. How does the structure of the small intestine relate to its function? 2. What would you predict to be the impact of surgical shortening of the small intestine on digestion and nutrient absorption in a human? 3. The Na/glucose co-transporter moves glucose against its concentration gradient from the intestinal lumen into intestinal cells. Does this transporter require energy in the form of ATP to perform this function? Explain your answer. 4. *Predict what would happen to glucose absorption in the small intestine if the Na/K ATPase in the intestinal cells was inhibited. Explain your answer. 5. ***Animals such as pythons (a type of very large snake) eats very large meals, and eats very infrequently. Pythons allow their small intestine to regress (become smaller and less active) between meals. Suggest a hypothesis to explain why this occurs. Would you predict this would happen in snake species that eat more frequently? Justify your answer.

Learning Objective 6: Explain how the intestines help to regulate water balance 1. Explain how secondary active transport of sodium is involved in re-uptake of water. 2. Predict what would happen to water reabsorption in the large intestine if you inhibited the Na/K ATPase on intestinal cells. Justify your answer. 3. Predict how changes in osmolarity in the gut could affect water reabsorption and cause diarrhea or constipation. 4. **Sorbitol is a sugar substitute that tastes sweet but that cannot be absorbed by the small intestine. Eating large amounts of “sugar free” candy or gum containing sorbitol can cause diarrhea. Propose a mechanism to explain this side effect of sorbitol consumption. Learning Objective 7: Explain how mutualisms between microbes and animals aid digestion 1. How do microbes in the gut improve the efficiency of nutrient extraction from plantbased food? 2. * The digestive system plays a role in protecting the body from harmful bacteria. Taking into account processes occurring in the stomach and the intestine, how might the digestive system protect the body from harmful bacteria? Learning Objective 8: Distinguish between macronutrients and micronutrients 1. Explain why some nutrients are required in large quantities and others are required only in small quantities

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Animal Nutrition – Practice questions Organized by learning goal. 2. Compare and contrast macronutrients and micronutrients. 3. Is water a macronutrient? Learning Objective 9: Discuss how macronutrients are used for energy and can be interconverted and used for growth/repair/storage 1. *Discuss how the second law of thermodynamics is relevant to explaining why organisms need nutrients and energy. 2. What is the difference between anabolism and catabolism? 3. Do both plants and animals perform cellular respiration? Explain your answer. 4. Compare and contrast carbohydrates, fats, and proteins as sources of energy. 5. Explain the role of acetyl CoA in allowing animals to interconvert among nutrients 6. Explain why glucose (and not fats or proteins) is used for anaerobic metabolism 7. What is the major storage form of nutrients in mammals? Explain your answer in terms of the properties of the various nutrients Learning Objective 10: Explain why different fuels are used for different activities 1. This graph depicts the use of different types of fuel by humans at rest and during exercise. Why do you think fat is being used preferentially at rest? Why do you think carbohydrate is being used preferentially during high intensity exercise?

2. Explain why phosphocreatine is the major fuel used by muscles during a sprint. 3. **Marathon running is an extremely challenging sport. Many marathon runners experience a phenomenon called "hitting the wall" when they feel like it is nearly impossible to run any more. Hitting the wall is more common in people who try to run at greater than 80% of their maximum exercise intensity, while individuals who run at less than 50% of their maximum exercise intensity are less likely to hit the wall (although they are unlikely to win the race at this pace). Using the data in the graphs from the previous two questions, why do you think this is the case? 4. **Marathon runners often "carbohydrate load" by eating a large meal that is rich in carbohydrates the day before an important race. What do think this would do to the probability of "hitting the wall? (Justify your answer).

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Animal Nutrition – Practice questions Organized by learning goal. 5. Using the data in the two graphs below, predict the level of exercise intensity that would be the most effective for fat loss. Justify your answer.

Learning Objective 11: Define and identify essential nutrients, and explain why the essential nutrients differ among animal species 1. What chemical element do proteins contain that is absent from carbohydrates and lipids? What does this mean in terms of an animal's ability to synthesize proteins? 2. Could you take food in which protein was the only macronutrient and use it to provide the building blocks needed to make carbohydrates? Justify your answer (assume that all essential micronutrients and water are provided by the diet). 3. Could you take food composed only of carbohydrates and use it to provide the building blocks needed to make proteins? Justify your answer. 4. Why are some amino acids termed "essential"? 5. Use Vitamin C as an example to show that organisms differ in their requirements for essential nutrients. 6. Different organisms vary in their nutritional requirements for vitamins. Why might the nutritional requirement for vitamins vary from one organism to another? 7. Corn is deficient in the amino acid tryptophan (which is an essential amino acid in humans), so humans cannot survive on a diet that contains only corn. However, corn moth larvae live exclusively on a diet of corn. How do corn moth larvae survive on a diet with such low tryptophan. 8. Cats do not need to consume foods containing high levels of vitamin C, but humans must do so to remain healthy. Explain why this is so. 9. *When we put out a hummingbird feeder, we often fill it with a mixture of sugar (a disaccharide) and water. But hummingbirds cannot survive on sugar-water alone. Instead, most hummingbirds supplement their diets by eating insects. Explain why hummingbirds cannot survive just by eating at a feeder, and why eating insects as well allows them to survive. 10. *Pea aphids feed exclusively on phloem sap of pea plants. Phloem sap is made up of mostly water and glucose, with some amino acids at very low levels. How might the pea aphids obtain all of the amino acids required to make the proteins necessary for physiological function?

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