Final answer:
To distinguish between a monkey and an ape, check for the presence of a tail, since monkeys generally have tails and apes do not. Other differences include body size, modes of locomotion, and relative brain size.
Step-by-step explanation:
When you see a primate in a zoo and want to determine whether it is a monkey or an ape, there are a few distinguishing features you can look for. The most apparent difference is the presence of a tail. Monkeys typically have tails, whereas apes do not. Additional differences include their size, movement, and intelligence. Apes are generally larger, move through trees or on the ground using their knuckles, and have larger brains relative to body size. In contrast, monkeys are smaller, more similar to other mammals in body structure, and walk on their palms when moving quadrupedally.