Sicentists classify organisms based on their similarities and differences. Old classification systems were based only on characteristics that could be observed with the eye, sometimes aided by a microscope. Size, shape, color, body structure, and method of food-getting are examples of such characteristics.
For many years, scientists classified all organisms as either plants or amimals. Today, scientists are able to study the molecules that make up organisms. For this reoson, classification systems may change as similarities and differences in molecules are discovered. One accepted classification is the division of organisms into five main groups, called kingdoms. The five kingdoms are the animal kingdom, the plant kingdom, the fungus kingdom, the protist kingdom, and the moneran kingdom.
Most organisms in the animal kingdom can move about. Some animals fly, some swim, and others walk on the ground. Also, animals cannot make their own food. They eat other organisms for food.
Plants have characteristics diffenrent from animals and organisms in other kingdom. Plants usually have a green substance called chlorophyll. They use chlorophyll to make food. Also, a plant usually spends its whole life in one place.
Organisms in the fungus kingdom, such as yeasts, molds, and mushrooms, do not move around as animals do. They do not have chlorophyll as plant do. They obtain food from the materials on which they grow.