Foundations of Life

Chapter 4

How many different kinds of living things do you think exist on Earth? Estimates have varied from about three million to nearly 100 million. In a recent study, a team of scientists put forth the number 8.7 million, a total that does not include the many species of bacteria that inhabit the planet. Of the 8.7 million species, almost 6.5 million live on land. The remaining species live in water.

Living things are found in all corners of Earth-from the deepest oceans, to the driest deserts, to the coldest ice caps-and every place in between. The planet is truly alive with living things.

In this chapter, you will study the variety of living things, from single-celled microbes to multicellular organisms.

In this chapter you will learn about:

Goal Setting

You encounter different species of organisms every day. They live in your home, in your classroom, and outdoors. Which of these organisms interests you most? What would you like to know about this organism?

  • Choose an organism and draw its picture.
  • Write the name of the organism.
  • Draw a picture of your organism.

Use the chart to write questions you have about the organism. As you read, return to the chart to write the answers to your questions.

Questions Answers