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Modified True/False
Indicate whether the sentence or statement is true or false. If false, change the identified word or phrase to make the
sentence or statement true.
____
1. The gradual change in a species over time is called adaptation. ____
F, evolution
____
2. Through natural selection, harmful variations gradually accumulate in a species. ___ F, helpful
____
3. When some members of a species become geographically isolated, they are less likely to form a new
species. __ F, more
____
4. An empty space called a cast is formed when an organism buried in sediments dissolves. __ F, mold
____
5. In sedimentary rock, the youngest fossils are usually found in the deepest layers. ___ F, oldest
______________________
____
6. The largest span of time in the Geologic Time Scale is Precambrian Time. _____ T
____
7. Darwin thought that species evolved rapidly. ___ F, slowly
____
8. The theory of punctuated equilibria proposes that species evolve through small changes over a long time.
F, gradualism
____
9. The more similar the DNA sequences of two species are, the more closely related the species are. T
____ 10. On a branching tree, a species is more closely related to a species on the same branch than to one on a
separate branch. _____T
Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
____ 11. A species is a group of similar organisms that
can mate with one another and produce fertile offspring.
____ 12. What did Darwin observe about finches in the Galapagos Islands?
Their beaks were adapted to match the foods they ate.
____ 13. The gradual change in a species over time is called
____ 14.
____ 15.
____ 16.
____ 17.
____ 18.
evolution.
A trait that helps an organism survive and reproduce is called a(n)
adaptation.
What did Darwin infer from his observations of organisms in South America and the Galapagos Islands?
A small number of different plant and animal species had come to the Galapagos Islands
from the mainland.
Which term refers to the process by which individuals that are better adapted to their environment are
more likely to survive and reproduce?
. natural selection
Which term refers to a species creating more offspring than can possibly survive?
overproduction
Differences between members of the same species are called
variations.
____ 19. How does natural selection lead to evolution?
Helpful traits accumulate among surviving members of the species.
____ 20. What is the role of genes in evolution?
Only traits that are controlled by genes can be acted on by natural selection.
____ 21. Which of these is one of the main ways that a new species forms?
A group is separated from the rest of the species.
____ 22. Which of these illustrates the impact of continental drift on the formation of new species?
Most mammals in Australia are marsupials, but few marsupials exist on other continents.
____ 23. What are fossils?
the preserved remains or traces of organisms that lived in the past
____ 24. How do most fossils form?
. A dead organism becomes buried in sediment.
____ 25. Entire insects have been perfectly preserved in
amber formed from the hardened sap of evergreen trees.
____ 26. How do scientists determine the actual age of fossils?
absolute dating
____ 27. What evidence is most important when using relative dating?
the position of fossils in sedimentary rock layers
____ 28. Most of what scientists know about extinct species is based on
the fossil record.
____ 29. Which term refers to a species that no longer has any living members?
extinct
____ 31. How long is Precambrian Time in the Geologic Time Scale?
4.6 billion years
____ 32. What theory proposes that evolution occurs steadily in tiny changes over long periods of time?
gradualism
____ 33. What theory proposes that species evolve during short periods of rapid change?
. punctuated equilibria
____ 34. What theory agrees with fossil records that show no intermediate forms for long periods of time?
punctuated equilibria
Essay
35. A horse and a donkey can mate with each other. Their offspring, called a mule, is not fertile. Do horses
and donkeys belong to the same species? Explain your answer.
No, horses and donkeys do not belong to the same species. Two organisms belong to the same species only if they can
mate and produce fertile offspring
36. Suppose a species lived in an environment that changed very little over millions of years. Which theory
about how fast evolution occurs would most likely explain the evolution of that species? Explain your
answer.
.Gradualism would most likely explain the evolution of that species. If the environment changed very little, a species
that was already adapted to the environment would not feel much pressure from natural selection to
evolve. Therefore, its evolution would be slow and gradual.
37. Explain how continental drift contributed to the evolution of new species.
.When the continents were one big continent, organisms could migrate from one part to another. When the continents
separated, species became isolated from one another and began to evolve independently.
ESSAY