2_1 The characteristics of living things

2 - 1 2. LIVING THINGS 2.1 THE CHARACTERISTICS OF LIVING THINGS The study of living things is called biology. In biology, living things are often called organisms . There are more than

3 000 000 different kinds of living organisms - kinds like grasses and ants, seaweeds and sharks, palm trees and people. But how do we know whether something is living or not? When we observe animals moving and feeding, it is obvious that they are alive. But plants are alive too. We can see that plants grow. Plants also make seeds that grow into new plants. All living organisms move, feed, grow and reproduce their own kind. M ovement, feeding, growth and reproduction are four characteristics of all living things. Three more are respiration, excretion and sensitivity . Each of these seven characteristics is explained below.

Growth All living things grow. Most organisms change in various ways as they grow.