Science and Life 7. [antikvár]

WHAT IS LIFE? Characteristics of Living Things When you look at the world of living things, you are impressed with the great variety of forms in which life exists. Today, there are about 2,000,000 recognized kinds of living things, and more are being identified every year. Living things rangé in size from the great blue whale, the largest animal in existence, and the giant redwood trees of our western states, to microorganisms that can be seen only when they are magnified hundreds of times with the aid of a microscope. Thousands of kinds of living things are composed of only one cell. Men and other complex organisms are composed of many cells, organized into specialized parts. Life can exist within a wide rangé of conditions. It can be found in the frozen polar lands and in the humid tropics. Life is present in the water, in the air, in the soil, and on the land. If you were asked "What is life?" you would find it difficult to give an exact answer. Could you define "life" by giving the characteristics of those things that are alive? What are the characteristics of living things? Divide a sheet of paper into two columns. At the top of one column write "Living" and at the top of the other write "Non-living." Name at least ten things under each heading. Explain the reasons for your grouping or classifying.