Classifying Living Things (Part 2)

What You'll Learn

Living things are organized into levels: cells form tissues, tissues form organs, organs form organ systems, and organ systems make up a complete organism.

Key Words

nucleus
membrane

Steps

Step 1 — Read

Review the background information on Ecosystems before starting.

Step 2 — Do

Compare the skeletal structures of a bird wing, human arm, and whale flipper using diagrams. Identify homologous bones and write what this tells us about common ancestry.

Step 3 — Observe

Note any unexpected results and think about why they happened.

Step 4 — Record

Share your findings with the class or a partner and discuss what you learned.

Check Your Understanding

Question 1

1 of 3

What do all living things have in common?