SOLVED

40. While we have seen how natural selection and the use of pesticides can lead to the development of resistant varieties of insects, two economically important flies, the Mediterranean fruit fly (Medfly) and the screwworm fly, can be driven to local extinction by the continuous release of sterile flies of those species. The critical factor is that the female of these species only mates once. But which of the following is/are also necessary for sterile release to work? A. The target species is truly just one species. B. The insect can be raised artificially in large numbers. C. The insects to be released can be sterilized with radiation without affecting their ability to attract a mate in the wild. D. All of the choices are correct. 41. British land snails are an example of disruptive selection. In the grassy fields, the light-banded snails escape bird predators. In the darker forest, the dark snails survive and the light-banded snails are eaten. The different colored snails have the opportunity to interact and breed across the British landscape. Why doesn’t this “disruptive selection” eventually lead to two separate species? A. There is no reproductive isolation to prevent gene flow. B. They are already two separate species, and the intermediate forms are hybrids. C. The color forms are probably not genetically determined. D. There must be some unknown factor producing an equal stabilizing selection “to hold the species together.” E. This will result in the formation of two species if given long enough time. 42. Which of the following reflect(s) the likely presence of (a) gene mutation(s)? A. Fruit flies subjected to intense radiation produce a wider array of variable offspring. B. A chemical leaking from the surface of an old abandoned coal mine alters a regulatory gene so that a cricket nymph develops an extra set of eyes. C. The bacteria that cause gonorrhea, a common sexually transmitted disease, have previously been killed by penicillin; however, after continuous usage of the antibiotic, penicillin-resistant strains are now becoming prevalent. D. Radiation causes an alteration in a DNA nucleotide sequence, which is discovered when mapped, but which appears to be neither increasing nor decreasing in successive generations. E. All of the choices are correct. 43. Another student proposes that handedness could just as easily be passed to children by how the parents carry the child and interact with it, a learning process that may perpetuate from the parents’ handedness. Assuming all parents and children are expressing their “true handedness,” the occurrence of which case below would cast the most serious doubt on a simple genetic basis for handedness, with left-handedness recessive? A. Two right-handed parents have a left-handed child. B. Two left-handed parents have a right-handed child. C. Left-handed parents only have left-handed children. D. Right-handed parents only have right-handed children. E. None of the choices are correct. 44. The Hardy-Weinberg equilibrium is usually met in populations in changing environments. Â Â