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Unformatted text preview: rs (Ll) and half would be red males (XrY) and half would be
calico females (XbXr). If these two F1 progeny were crossed to create an F2 generation, 3 of
the 16 resulting kittens would be short-haired calicos (use a Punnett square to figure this out).
Therefore the answer is A (1/2 and 3/16).
55. B. Answers A, C and D are wrong because all contain only a single copy of the X
chromosome (and two are needed for X-inactivation to take place). Therefore, the only
possible answer is XXY, in which non-disjunction occurred in one of the parents of this
56. A. Answer D is incorrect because it is not specifically X-linked. Answers B and C are
incorrect because X-deactivation occurs randomly. There is no way to selective inactivate
only maternal or paternal X-chromosomes.
57. D. The passage explains that the pigment-producing cells originate at the neural crest (which
later forms the spinal chord of the cat) and migrate away from the crest. Therefore, areas
furthest from the body are most likely not to have these pigment-producing cells. Answers A,
B and C all are part of or lie along the neural crest structure and are therefore most likely to
express color. Answer D, the paws, are the furthest away from the neural crest and therefore
the mostly likely to be white.
58. D. All of the options are involved in genetic expression, thereby contributing to the
phenotype of an organism.
59. C. This requires that you have some knowledge regarding the end fates of embryonic tissue.
Skin cells are derived from the ectodermal germ layer of the embryo.
60. D. Inbreeding involves the mating of relatives or a very small gene pool. Therefore it is
unlikely to increase the genetic diversity of the population. The level of aggression in a
population is not necessarily increased by inbreeding. The rate of spontaneous mutation is
relatively constant across a species and has nothing to do with patterns of reproduction.
Therefore, it follows that incidence of expression of deleterious recessive traits would
increase. If the participants in the inbreeding are carriers of recessive traits, their offspring
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This note was uploaded on 03/23/2011 for the course CHEM 100 taught by Professor Vallis during the Spring '11 term at Dalhousie.
- Spring '11