Answer
Plate tectonics have altered terrain and climate, leading to new habitats into which different forms of life could radiate and to mass extinctions when terrain and/or climate changes eliminated the places where many of those organisms lived.
Work Step by Step
The thing to see here is, from a review of the chapter, that plate tectonics have brought landmasses together and pulled them apart, driven the creation of mountain ranges and the closing of seas. All of this means that places for organisms to live in have appeared and disappeared over time because of plate tectonics.
