25 – Flashcards
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How can biological fitness be estimated?
a. Document how long different individuals in a population
survive.
b. Count the number of healthy, fertile offspring produced by
different individuals in a population.
c. Determine which individuals are strongest.
d. Determine which phenotype is the most common one in a given
population.
answer
b
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True or false? Some traits are considered vestigial because they existed long ago.
answer
False
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What is an adaptation?
a. a trait that improves the fitness of its bearer, compared with
individuals without the trait
b. a trait that changes in response to environmental influences
within the individual's lifetime
c. an ancestral trait—one that was modified to form the trait
observed today
d. the ability to produce offspring
answer
a
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Why does the presence of extinct forms and transitional features in the fossil record support the pattern component of the theory of evolution by natural selection?
a. It supports the hypothesis that individuals change over time.
b. It supports the hypothesis that weaker species are eliminated by natural selection.
c. It supports the hypothesis that species evolve to become more complex and better adapted over time.
d. It supports the hypothesis that species change over time.
answer
d
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Traits that are derived from a common ancestor, like the bones of
human arms and bird wings, are said to be _____.
answer
homologous
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According to data presented in this chapter, which of the following statements is correct?
a. When individuals change in response to challenges from the
environment, their altered traits are passed on to offspring.
b. Species are created independently of each other and do not
change over time.
c. Populations—not individuals—change when natural selection
occurs.
d. The traits of populations become more perfect over time.
answer
c
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Some biologists summarize evolution by natural selection with the phrase "mutation proposes, selection disposes." Mutation is a process that creates heritable variation. Explain what the phrase means.
answer
Mutation produces new genetic variations, at random, without any forethought as to which variations might prove adaptive in the future. Individuals with mutations that are disadvantageous won't produce many offspring, but individuals with beneficial mutations will produce many offspring. The beneficial mutations will thus increase in frequency through selection.
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Explain how artificial selection differs from natural selection.
answer
Artificial selection is determined by human choice and is goal directed, whereas natural selection is the un- planned differential reproductive success of individuals that vary in their heritable traits.
question
Why don't the biggest and strongest individuals in a population always produce the most offspring?
a. The biggest and strongest individuals always have higher fitness. b. In some environments, being big and strong lowers fitness.
c. Sometimes the biggest and strongest individuals may choose to
have fewer offspring.
d. Sometimes the number of offspring is not related to fitness
answer
b (In some environments, being big and strong lowers fitness.)
question
QUANTITATIVE The graphs in Figure 25.16 show that the average beak depth of medium ground finches increased after the drought.
answer
There were 751 finches before the drought and 90 finches afterward, so only 90/751 = 0.12, or 12 per- cent, survived. There were more finches with deep beaks before the drought only because the population was much larger, but the average beak depth increased after the drought.
