The Fourth Mass Extinction Occurred About 200 Mya at the End

question 85

Multiple Choice

The fourth mass extinction occurred about 200 mya at the end of the ________ period.This extinction eliminated 35 percent of the existing animal species,including ________.

• A) Triassic; reptiles, early dinosaurs, and the first mammals
• B) Jurassic; dinosaurs, the first birds, and many flowering plants
• C) Silurian; insects, birds, and mammals
• D) Carboniferous; insects, birds, and mammals

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Definitions:

Microfilaments

Fine, thread-like protein fibers, predominantly actin, that are part of the cytoskeleton in eukaryotic cells.

Actin

Spherical protein that plays a role in cell movements; the main component of thin filaments in a sarcomere.

Vesicle

Saclike, membrane-enclosed organelle; different kinds store, transport, or break down their contents.

Fusion

The process of combining two or more entities into a single entity, often referring to the merging of atomic nuclei to form a heavier nucleus, releasing energy.