Microsoft Word - Answers to Study Questions after midterm II.doc

Microsoft Word - Answers to Study Questions after midterm II.doc

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Keen 2B Answers to Study Questions after Midterm II 1. Suppose you hear crickets chirping. Males call to attract females. One set of sounds has a series of short chirps followed by a long pause. The other set of sounds has three long chirps and a short pause. The field guide says that there are two closely related species present. Which of the following is likely? a) female crickets search for males visually b) the two cricket species are mechanically isolated c) the two cricket species are temporally isolated d) female crickets identify the species of male by the call e) spatial isolation keeps these two species apart Notice that there were two different sound patterns described. 2. Still thinking about the crickets from question 1, suppose that females occasionally select a male of the wrong species as a mate. Which of the following would still allow two distinct or “good” species of crickets to persist? a) high survival and reproduction of hybrid offspring b) hybrid breakdown c) hybrid sterility d) b and c e) a, b, and c Recall that in the biological species definition, hybrid offspring do not form or persist. 3. If there is an error in meiosis so that a gamete has more than the typical number of chromosomes, and this gamete fuses with another just like it, the resulting zygote would be: a) haploid b) diploid c) triploid d) polyploidy e) multiploid This is defined as anything greater than 2N. 4. The earliest horses are known from fossils to be small dog-like animals in genus Hyracotherium . Over evolutionary time there has been a steady change in the position of the feet while running. The number of toes on the ground has been reduced from 5 to 3 to 1. This kind of change within a single lineage is called: a) stasis b) extinction
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Keen 2B c) anagenesis d) cladogenesis e) speciation This is change within in a lineage—typically in response to directional selection. 5. What is a sister taxon? a) the ancestor of two modern species b) the part of a lineage that did not go extinct c) two species that live in the same place d) half of a lineage that split during cladogenesis e) the opposite of a brother taxon We describe each ancestral taxon as splitting into two descendant lineages called sister taxa. 6. A cladogram is: a) a graphical representation of ancestors and descendants b) a hypothesis about evolutionary relationships among taxa c) an illustration of the branching pattern of chromosomes d) a and b are true e) a, b, and c are all true It is a hypothesis in that it represents one possible set of relationships among taxa. In BIS 2C, you will learn that there are many possible trees for a set of taxa. For example, for 3 taxa, A, B, and C, there are 3 possible trees—one shows A and B as sisters, another shows A and C as sisters, and the third shows B and C as sisters. You will learn to consider evidence to discover the most likely tree—thus, the most likely evolutionary relationships among the taxa. 7.
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This note was uploaded on 01/21/2012 for the course ECON 2a taught by Professor Xi during the Spring '11 term at Cornell College.

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Microsoft Word - Answers to Study Questions after midterm II.doc

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