Exam 24: The History of Life on Earth

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

Which statement about the Phanerozoic eon is false?

Refer to the figure, which shows an imaginary name scheme for an undisturbed site with distinct fossil assemblages in the top five layers of strata. Your research team is excited to find (through comparison with other sites around the globe) that these assemblages correspond to some of the known historical periods on Earth.Specifically, the "Leverett" assemblage contains only microscopic life forms, while the "Hadley" stratum contains diverse marine invertebrate animals but no evidence of terrestrial life.Based on this information, which eon in Earth's history contains the "Hadley" stratum?

Refer to the figure, which shows a series of stromatolite fossil formations from Shark Bay, Australia. What is the historical significance of these fossils?

Which of the following is the most likely cause of extinction for a large population of organisms?

The first terrestrial arthropods began to occupy land during the

Which of the following represents a correct chronological ordering of Earth's geological history, from earliest to latest?

Oxygen-generating cyanobacteria liberated enough O₂ to open the door to _______ reactions in metabolic pathways, leading to the evolution of _______ cells.

About _______ years ago, prokaryotes probably first added adequate quantities of oxygen to the atmosphere to allow for the evolution of aerobic cellular metabolism.

Oxygen concentrations on Earth were at their highest

Refer to the graph showing the decay of a radioactive substance. If this substance started decaying 280,000 years ago, and 4 mg of it remains, there was roughly _______ mg of the original substance.

At the end of the _______ period, atmospheric oxygen concentrations decreased from about 30 percent to 15 percent due to plant death associated with the widespread drying of swamps.

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

Which statement about patterns or processes in the evolution of life is false?

Coal is the fossilized remains of _______ from the Carboniferous period.

The oldest known _______ were found in the Triassic fossil assemblage.

Scientists estimate that most species have never been named because approximately _______ living species and _______ fossil species have been described.

Which of the following could not be dated by means of radioactive carbon?

Place the following organisms in chronological order, according to when they appeared in the fossil record.

Which group is documented in fossils from the Proterozoic eon?