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Unformatted text preview: Essential amino acids are A. all of the amino acids required to make proteins. B. those that cannot be made in the body. C. those that contain nitrogen. D. obtained only by eating plants. E. obtained only by eating animals. A l complete digestive tract z differs from a gastrovascular cavity in that only the complete tract A. permits extracellular digestion. B. has tentacles to help with ingestion. C. uses its surface area for nutrient absorption. D. has specialized compartments. E. allows elimination of undigested wastes. Figure 41.7 Mouth Tentacles Food Epidermis Gastrodermis Food particles engulfed and digested Food particles broken down Digestive enzymes released 1 2 3 Figure 41.8 Crop Gizzard Intestine Anus Esophagus Pharynx Mouth (a) Earthworm Midgut Esophagus Crop Mouth Stomach Gizzard Intestine Anus Anus Rectum Esophagus Crop Hindgut Foregut Mouth Gastric cecae (b) Grasshopper (c) Bird Figure 41.9a Liver Salivary glands Gall- bladder Esophagus Pharynx Oral cavity Sphincter Tongue Pancreas Small intestine Large intestine Rectum Anus Sphincter Stomach Duodenum of small intestine Figure 41.9b Mouth Stomach Esophagus Pancreas...
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- Spring '11