7B STAAR Practice

34 After examining the fossil record, scientists have determined that scorpions today are much smaller than their extinct ancestors. For example, Jaekelopterus rhenaniae, a giant scorpion species that lived 255 million to 460 million years ago, was 2.5 meters long. Which of the following conclusions is supported by this information?

• Scorpions living today have increased their numbers since they first appeared.

• Scorpions in the fossil record are smaller than their descendants are.

• Scorpions have changed as a result of natural selection.

• Scorpions do not appear in their original state in the fossil record.

5 The cladogram shows the evolution of land plants as indicated by fossil records. Which discovery would challenge the validity of this cladogram?

• A large aquatic vascular plant about 200 million years old

• A species of algae that has existed for less than one million years

• A moss species that has existed for less than 380 million years

• A fossil of a fern more than 425 million years old

38 This diagram of the fossil record represents changes in mollusks over millions of years.

How can the pattern of change in the fossil record best be explained?

• The mollusks were well adapted to their stable environment. A large, sudden change occurred in their environment. After the change the mollusks with the bigger shells were better adapted for the new environment.

• The mollusks were well adapted to their stable environment. The mollusks hybridized with a smaller species of mollusk. A new species of mollusk with a bigger shell resulted.

• The mollusks were not well adapted to their environment. The length of the mollusks’ shells changed gradually over time. The mollusks in the original population that had small shells died over a period of many years.

• The mollusks were well adapted to their environment. Humans introduced a new species of mollusk that was not adapted to this environment. The introduced mollusk outcompeted the native mollusk species.

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7B

14 The graph shows the number of taxa of reptiles whose fossilized tracks have been found.

Which statement is best supported by these data?

• Competition for food and shelter among reptile species was very low during the Triassic period.

• A great extinction occurred during the Jurassic period.

• Environmental conditions for speciation were most favorable for reptiles during the Permian period.

• Reptiles adapted to a terrestrial environment during the Cretaceous period.

35. Niles Eldredge and Stephen Jay Gould researched the lenses of the eyes of fossil trilobites of different species. In 1972 they published a paper in which they described the tendency of a species to remain the same until a sudden change in the environment causes a new related species to appear.

Which hypothesis was most challenged by the work of Eldredge and Gould?

• Redi’s hypothesis that spontaneous generation does not occur

• Haeckel’s hypothesis that embryological development mimics the evolution of species

• Wallace’s hypothesis that geography affects the distribution of species

• Darwin’s hypothesis that the development of species is a slow, gradual process

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7B

12. The diagram shows data on the evolution of horses. The data in the diagram is evidence that —

• F. a new species of horse suddenly appeared

• G. horses slowly developed over time

• H. horses have similar stages of rapid embryological development

• J. horses have a common ancestry with other hooved animals

22. When multiple transitional fossils are found in many rock layers, they provide evidence of —

• seasonal variation in the diet of a species

• gradual change of a species over time

• DNA functioning as the genetic material of organisms

• an unchanging environment

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7B

Organisms D and C clearly lived in an aquatic (water) environment. Organism A does not look like it lived in the water. What is the most likely explanation for this?

• The fossil in layer A died on land and was carried to the water

• The fossils in layer C and D did not live in the same location as the fossil in layer A

• The environment changed over a long period of time. It used to be under water, but is not anymore

What is a likely event that occurred between fossil layers B and D?

• explosion of new species

• mass extinction

• can not tell from the image

• small changes to the environment

Starting at layer H (at the bottom) what pattern do you notice as you move up towards layer B

• organisms become more complex

• random arrangement of organisms

• organisms go from water only to land only

• organisms become more simple