Sesson 2: Natural Selection Basics

Key Idea

All living things have needs, like finding food and staying safe. An organism's body parts and behaviors are its traits. These traits help it meet its needs in its environment.

Some traits make it easier for an organism to get what it needs to survive. For example, a hummingbird with a long beak can easily reach nectar deep inside a flower. But a hummingbird with a short beak might struggle to get food from that same flower, making it harder for it to live.

Key Idea

The shape and form of a trait is its structure. This structure determines the trait's job, which is its function. For example, the structure of a hummingbird's beak can be long and thin. The function of this beak is to drink nectar from deep inside a flower.

A trait's function helps an organism do important things to live, like getting food or hiding from danger. If a trait's structure is a good match for its function in the environment, the organism is more likely to survive.