ACT真題每日一練12.15

2015/12/15 瀏覽次數:7 收藏
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  Science Question for Tuesday, December 15th, 2015

  Abandoned cornfields have been the sites of investigations concerning ecological succession, the orderly progression of changes in the plant and/or animal life of an area over time (see Figure 1).

  (Note: The plants are ordered according to their appearance during ecological succession.)

  During the early stages of succession, the principal community (living unit) that dominates is the pioneer community. Pioneer plants are depicted in Figure 2.

  The final stage of ecological succession is characterized by the presence of the climax community, the oak-hickory forest. Figure 3 depicts the gradual change from pine to hardwoods.

  Figures adapted from Eugene P. Odum, Fundamentals of Ecology. ©1971 by Saunders College Publishing/Holt, Rinehart, and Winston, Inc.

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  Given the information in Figure 1, which of the following conclusions concerning ecological succession in an abandoned cornfield is most correct?

  F. Succession in an abandoned cornfield begins on bare rock.

  G. Succession is characterized by the replacement of one plant community by another until a climax community has been achieved.

  H. The height of the plants in the communities decreases as succession progresses to the climax stage.

  J. The plant species change continuously during succession, but the change is more rapid in the later stages than in the earlier stages.