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GEL 113 Homework 14 Answer sheet Study Questions for Web Notes and Chapter 9 Part I: Multiple Choice: 1.B 2.D 3.A 4.D 5.C Part II: True or False: 6.F 7.F 8.F 9.T 10.T 11.F Part III: 12. The food web is the sequence from plants through herbivores through predators (often represented as a food pyramid). Ectothermic predators do not need to eat much, because most of their energy comes from the sun. Endotherms require 4 to 24 times more food since they must produce their own heat. As a result, endothermic predators need a much larger number of prey animals, so in nature we find the predator-prey ratio for endotherms to be very small (generally less than 2%). Ectothermic predators can have a predator-prey ratio of up to 30%. The average predator-prey ratio for carnivorous dinosaurs was about 2%, suggesting that they were endothermic. 13. In these areas the sun provides little warmth, and during the winter it is often dark for months. Ectotherms could not survive under these conditions unless they hibernated for considerable periods of time. Most dinosaurs could not have hibernated because they were much too large to build burrows or fit into sheltered crevices for protection from predators during their lengthy sleep. Also, no living ectotherms migrate substantial distances (the other alternative) because they lack the ability for sustained energy output that prolonged locomotion requires. 14. a)endotherm - animals that have internal mechanisms to produce heat. b) ectotherm - animals that depend on external sources of heat, primarily sunlight, to keep their body temperatures elevated. c) homeotherm - animals whose internal temperature stays within a range of plus or minus 2 degrees Centigrade of its average value. d) gigantotherm - an animal which would be homeothermic simply because of its large size.
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