1. KEY CONCEPT Unifying themes connect concepts from many fields of biology.

2. I. All levels of life have systems of related parts.
A. A system is an organized group of interacting parts.
1. A cell is a system of chemicals and processes.
2. A body system includes organs that interact.
3. An ecosystem includes living and nonliving things that interact.

3. B. Biologists study many different systems.

4. II. Structure and function are related in biology.
Structure- refers to what something looks like or how it is made
Function- refers to the way something works or what it does

5. C. Structure determines function.
1. Proteins with different structures perform different functions.
2. Heart muscle cells have a different structure and function than stomach muscle cells.
3. Different species have different anatomical structures with different functions.

6. III. Organisms must maintain homeostasis to survive in diverse environments.
Homeostasis is the maintenance of constant internal conditions.
1. example- sweating, shivering, blood sugar

7. B. Behaviors and adaptations can help maintain homeostasis.

8. IV. Evolution explains the unity and diversity of life.
A. Evolution is the change in living things over time.
1. The genetic makeup of a population of a species changes.
2. Evolution can occur through natural selection of adaptations.
3. Adaptations are beneficial inherited traits that are passed to future generations.

9. B. Evolution accounts for both the diversity and the unity of life.

10. What are the four themes of biology?
Systems
Structure and Function
Homeostasis
Evolution

11. For each of the following descriptions, indentify which theme of biology is being described.

12. A wolf has sharp teeth for catching prey.

13. Over time, the colors of this species of moth have changed, and it now blends in very nicely to the leaves of a tree.

14. When a person eats a lot of sugar, their body produces insulin to maintain the body’s blood sugar level.

15. These fish interact with one another and with the algae, insects, water and sunlight that are in the river.

16. These leaves are really big so that they can capture a lot of sunlight.

17. All of these organs work together to break down food and absorb energy.

18. This dog is panting to keep itself cool.

19. These cacti a very good at conserving water, an adaptation that allows them to live in very hot places.