SA 22 1·Birds and bats are winged vertebrates. The wings of these two animals ar
ID: 194514 • Letter: S
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SA 22 1·Birds and bats are winged vertebrates. The wings of these two animals are homologous independently evolved inherited from their common ancestor identical in structure, but bats lost their feathers 8 million years ago that two closely related species both release gametes into the ocean in the same place at the same d) very similar in the details of their structure e) 2. Suppose could be effective in preventing gene flow time. Which of the following methods of reproductive isolation between the two species? a) gametic isolation mechanical isolation c) hybrid sterility a and b a and e e 3. In a situation where natural selection favors individuals with the average phenotype, and acts against the extremes what kind of selection is occurring A directional selection divergent selection stabilizing selection t selection 4. The essential difference between vicariant speciation versus a founder event is that vicariance involves splitting while a founder effect is fusing of two populations. B) the founder effect is the reverse of vicariant speciation. although a population is split by a vicariant event, the population size and environment does not alter gene fréquencies as does a founder event. D although a population is split by a founder event, the population size and environment does not alter gene frequencies as does a vicariant event 5. Which of the following is required for natural selection to occur in a population? A. Variation in the population B. Inheritance of genetic variation C. Differential reproduction so that more fit individuals produce more offspring umulation of adaptive traits so that they increase in the population E. All of the choices are correct 6. occurs when a fertilized egg enters cell division without further growth in volume. B Cleavage@ Gastrulation C. Differentiation D. Embryology 7. In nearly a metazoa, "germ layers" is a term that describes A. the germ cells. foreign cells that enter the embryonic process. ©mesoderm, etoderm and endoderm " D. the germ line, in contrast to the somatic or body cells 8. The process of speciation is easy to observe in natural populations B is complete when two taxa are reproductively isolated C takes place only when two speciating populations are allopatric D. occurs most often due to temporal isolationExplanation / Answer
1)correct option: (b)
according to modern evolutionary studies, the birds and bats are "independently evolved".
if consider their ancestors that the primitive bird "Archaeopteryx" has a close relationship with birds. and the Arboreal Chriacus has some close relationship with bats and other hooved mammals.
2)correct option: (d)
usually, Prezygotic barriers prevent fertilization results from interspecies mating. the gametic isolation and mechanical isolation both are this types of Prezygotic barriers. so, if the egg and sperms(gametes) come into contact then also the fertilization of these different species will not occur.
3)correct option: (c)
usually, the stabilizing selection favours the "intermediate variants" and oppose the individuals with extreme phenotypes.
but the directional and diversifying selection favours the extreme phenotypes.
4)correct option: (b)
variant speciation occurs when biological populations of the same species become isolated from each other to an extent that prevents or interferes with genetic interchange. but in founder event, a new population will form by a small number of individuals from a large population.
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