Complex sentence: A population cycle in zoology is a phenomenon where populations rise and fall over a predictable period of time because there are a number of factors which influence population change such as availability of food, predators, diseases and climate.
Split into simpler sentences: A population cycle in zoology is a phenomenon where populations rise and fall over a predictable period of time. Because there are a number of factors which influence population change such as availability of food, predators, diseases and climate.