Life and Geologic Time Answers

Scientists used major changes in life forms in the fossil record to form the geologic time scale.

The division of Earth’s history into smaller units makes up the ____.a.erasc.periodsb.geologic time scaled.sequence of events

Geologic time is divided into units based upon types of ____.a.sedimentary rocksc.organismsb.climatic changesd.igneous rocks

Dog breeding is an example of natural selection.

Plate tectonics may affect organic evolution because movement of plates may cause a change in ____.a.natural selectionc.Pangaeab.the environmentd.the geologic time scale

Changes in the trilobite exoskeleton can be attributed to ____.a.changing environmentsc.inter-species matingb.competition for survivald.both a and b

If a species can adapt to a changing environment, or ____, its descendants will survive.a.evolvec.stay the sameb.become extinctd.none of the above

____ on the geologic time scale are marked by major, striking, and worldwide changes in the type of fossils present.a.Erasc.Epochsb.Periodsd.all of the above

Trilobites are index fossils because they ____.a.changed slowly through timec.exhibit specific characteristicsb.lived over large areas of the worldd.all of the above

The longest subdivision in geologic time is a(n) ____.a.epochc.centuryb.periodd.eon