13 2 Digestion Nutrients and Food Acquisition BIO361T Fall 2014 1 Some macromolecules in food are used for their bond energy to create ATP a What is another major function of ingested macromolecules Hydrolyzed into monomers that are used to build macromolecules the cells need b This Thanksgiving you may indulge in a large meal then get warm and sleepy Why does ingestion of a large meal produce excess heat Specific dynamic action some energy in food is used for digestion and released as heat c What happens to food that is indigestible It is egested or excreted through the feces d Why might a vitamin deficient rabbit practice coprophagy the eating of its own feces It is a second chance to absorb vitamins 2 Each step in the food chain represents approximately a 10x loss in energy content a Explain why this is Not all of the energy in the organism will be conserved when it is eaten Some will be lost as SDA heat b Why might this be an argument for eating a more plant based less animal based omnivorous diet Shorter food chains lose less energy than longer food chains 3 An animal s diet must contain enough calories to meet its metabolic needs which vary between species and within individual animals a What are three factors that can differ between species that affect metabolic rate Activity heart rate environmental temperature size b What are three factors that can vary within an animal that affect metabolic rate c A 30 g meadow vole must consume 175 g of food each week 6x its body weight A 1900 kg rhino must consume only 650 kg 1 3 its body weight Explain the discrepancy between caloric needs and body size Metabolic rate of the rhino is much lower than the vole Because its cells are not making ATP as quickly they do not need as much energy from food d Why do you think this discrepancy is consistent across species of birds and mammals but not lizards and amphibians They do not maintain constant body temperature by varying metabolic rate Their metabolic rate does not need to decrease to compensate for a larger body because a larger body is not much more energetically expensive 4 Is the digestion that occurs in the lumen of the GI tract extracellular or intracellular Explain your answer Extracellular 5 Some proteins are hydrolyzed in the lumen of the stomach or intestine by proteases a What is the product of this process Amino acids b How are these products absorbed by cells Secondary active transport through amino acid Na cotransporters Each has its own channel expressed on the apical side of gut epithelial cells and are then absorbed by the blood c Infant mammals acquire antibody proteins from their mothers through the milk they ingest How are these proteins absorbed Whole through endocytosis on the apical side then exocytosis to the blood 6 Animals are heterotrophs Heterotrophs eat autotrophs like plants Define the words heterotroph and autotroph and explain why heterotrophs have to eat autotrophs Heterotroph eats other things for energy Autotroph makes its own food from inorganic material All cells need energy in the form of ATP Autotrophs can capture energy from the environment that is in sunlight and store it in chemical bonds Heterotrophs cannot so they must eat autotrophs to get more energy 7 Many animals have symbiotic relationships with other organisms that supply essential nutrients or otherwise aid in digestion Classify each of the following examples of symbiotic organisms as an enterosymbiont an exosymbiont or an endosymbiont a Birds eat beeswax which is hydrolyzed into shorter carbon units by bacteria in the cecum enterosymbiont b Worms in deep sea hydrothermal vents do not have GI tracts as adults They have internal sacs called trophosomes that house autotrophic bacteria endosymbiont c Leaf cutter ants pass leaf fragments to fungi that the colony cultivates They then eat the fungi which have digested the leaf fragments exosymbiont d Cnidarians have photosynthetic zoochlorellae on their bodies which use light energy to produce glucose and maltose exosymbiont e Although many animals are herbivorous no animal has enzymes that hydrolyze the structural polysaccharide found in plants cellulose Ruminants and termites have cellulase producing bacteria in their gut that release monosaccharides or ferment the cellulose to release fatty acids enterosymbiont f Humans that do not make lactase cannot metabolize lactose the sugar in milk Instead the lactose is metabolized by bacteria in the gut which produce methane gas as a byproduct enterosymbiont
View Full Document
Unlocking...