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1. Evolution is change over time. Natural selection is the mechanism that explains how it happens.
2. The current belief at the time was Earth was only a thousand years old, and thus not enough time existed to allow evolution to occur. The geologists, however, provided the insight that Earth was actually billions of years old, providing plenty of time for the slow process of natural selection. Furthermore, Earth itself could change during that huge amount of time.
3. The principle of inheritance of acquired characteristics believes that traits acquired during one’s lifetime could then be passed on to the offspring. This isn’t true, because a trait must be genetic for it to make it to the next generation.
4. An adaptation is a helpful trait found in a population that is the product of natural selection.
5. A species of woodpecker that evolved to possess brightly colored head feathers is an example of microevolution. The ancestral woodpecker that gave rise to many different species better adapted for their particular environment is an example of macroevolution.
6. a–4; b–3; c–2; d–1
7. In natural selection, the environment selects the most-fit phenotype. In artificial selection, humans select the most-fit phenotype.
8.
a. Any beneficial genetic mutation will be passed on to the next generations. False. Only mutations in the gametes (eggs and sperm) are able to be passed on to the next generation.
b. Populations, but not individuals, are able to evolve. True.
c. Once a most-fit phenotype is selected through evolution, the population’s adaptations are “fixed” and will no longer change. False. An adaptation that was considered beneficial at one point in a population’s lifetime can change. If the environment changes, so do the adaptations.
9. First, there needs to be variation in a population (individuals within a population are born with genetic differences). There are too many offspring for the environment to support. Due to the limited resources, there is a lot of competition among members of a population, and any individual that has a trait that makes it better able to outcompete others will end up surviving. These most-fit individuals are the ones left to reproduce and pass on their specific genes to the next generation. This results in a larger percentage of the next generation having these “most-fit” alleles.