2 - Origin of Animals, the Cambrian Explosion and Extinctions

What technique uses the known decay rate of radioactive elements to determine the age of rocks or fossils?

Radiometric dating

What is a variant of an element with a different number of neutrons, used in dating rocks?

Isotope

What are layered rock structures formed by ancient mats of photosynthetic microorganisms called?

Stromatolites

What are single-celled organisms that lack a membrane-bound nucleus?

Prokaryotes

What organelle is responsible for producing energy (ATP) in eukaryotic cells?

Mitochondria

What organelle in plant and algal cells is responsible for photosynthesis?

Chloroplast

What is the evolution of organisms made of many cells called?

Multicellularity

What is the geologic period before the Cambrian known for an assemblage of larger, diverse soft-bodied organisms?

Ediacaran

What geologic period (about 542-488 mya) marks the sudden appearance of fossils resembling modern animal phyla?

Cambrian

What is the sudden appearance of fossils resembling modern animal phyla in the Cambrian period called?

Cambrian explosion

What geologic period's extinction event, 251 mya, defines the boundary between the Paleozoic and Mesozoic eras?

Permian

What geologic era (251-65.5 mya) was dominated by dinosaurs and saw the emergence of the first mammals?

Mesozoic

What geologic period's mass extinction, 66 mya, killed about half of marine species and most dinosaurs?

Cretaceous