Sixth Bio180 Practice Exam
Thursday, November 8 12:30-1:20 p.m.
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Question 1 Suppose that a plant lineage lacking alternation of generations evolved from an angiosperm ancestor. For this to happen, what alterations would have to occur in the meiotic products of the angiosperm microsporangium and megasporangium? Question 1, Sample answer: The haploid cells produced by a microsporangium would have to develop into sperm cells, instead of dividing by mitosis to form a pollen grain. The haploid cells produced by a megasporangium would have to develop into eggs, instead of dividing by mitosis to form a female gametophyte. Question 2 Defend the claim that sexual selection occurs in plants, and that it is particularly intense in angiosperms that are pollinated by animals (versus wind pollinated species or species without pollen, where sperm swim to the egg). Question 2, Sample answer Sexual selection is based on heritable variation and differential success in obtaining mates. In angiosperms that are pollinated by animals, "obtaining mates" means attracting an animal pollinator. It is logical to predict that variation among individuals in ability to attract an animal pollinator will be much higher than variation among individuals in successful wind pollination or sperm swimming. Question 3 Many the of antibiotics in use today were originally isolated from soil-dwelling fungi. What is the adaptive significance of antibiotic production by fungi? Question 3, sample answer They eliminate bacteria that might compete with fungi for nutrients in the soil. Question 4 How are the following three statements related? 1) Cocaine, tetrahydrocannibinol (THC), opium, nicotine, caffeine, and an array of other bioactive compounds are synthesized by plants as a defense against herbivores. 2) Adult sponges do not move. 3) Chemical and pharmaceutical companies are intensely interested in sponges as a source of novel, commercially valuable molecules. Question 4, sample answer Because they don't move, sponges (and plants) can't "run away" from predators. Like plants, sponges are probably protected by molecules that defend them against predators. Some of these molecules could be useful for medicinal or industrial purposes. Question 5 When some ministers asked him what his study of biology had taught him about the nature of God, J.B.S. Haldane is said to have replied, "an inordinate fondness for beetles." In the context of your studies of animal species diversity, what did he mean? Question 5, sample answer Insects are the most species-rich lineage among animals, and most insects are beetles.