Exam 18: The History of Life on Earth

In the upper atmosphere,the bombardment of neutrons with nitrogen-14 varies somewhat over time.If in the past this rate had been higher,objects dated by _______ dating would now appear _______ than they really are.

The heat that drives plate tectonics is driven by

The first person to put forth the idea that Earth's continents are in continual but slow motion was

Suppose you were to drill a hole toward the center of Earth.Which of the following is the correct order of the layers you would encounter?

Which statement about radiometric dating is true?

Which statement about the Cambrian is true?

Supporting the claim that a meteorite caused the mass extinction at the end of the Cretaceous period,abnormally high concentrations of _______ have been found in rocks dating from that time.

Which of the following did not occur during the Pleistocene?

After the eruption of a major volcano,the concentration of _______ is likely to increase greatly,and the temperature is likely to _______.

The appearance of multicellular organisms coincided with increased levels of _______ in Earth's atmosphere.

At normal levels of oxygen,selection is _______ for body size in Drosophila.At higher levels of oxygen,the flies experience _______ selection.

What would be the most convincing evidence that an extraterrestrial event had led to a climatic change that resulted in extinction of a group of organisms?

Why are assemblages of fossils seen in successive geological periods so different?

Larger single-celled organisms require a higher oxygen concentration than smaller ones do because the large cells

In undisturbed sedimentary rock,strata from the _______ are immediately below rocks from the Ordovician.

Rocks that are formed when grains accumulate at the bottom of bodies of water are called _______ rocks

Which process or event is not considered a plausible hypothesis for the causes of mass extinctions?

Which statement about continental drift is true?

Fossils that are one hundred million years old date from the _______ period.

Which continent was likely affected the most by the meteor strike that led to the demise of non-avian dinosaurs?