Introduction | Section 1 | Section 2 

Part 1 | Part 2 | Part 3 | Part 4 | Part 5

Biology: The Nature of Science and Biology: Part Five

Seven Unifying Themes of Biology

Theme	Key Points	Examples
1. Cellular Structure and Function	All organisms are composed of one or more cells. Some organisms are unicellular (have one cell) while others are multicellular (composed of many cells).	Unicellular: amoeba, paramecium Multicellular: humans, giraffe
2. Reproduction	All living organisms can reproduce. Reproduction is the process by which organisms make more of their own kind from one generation to the next.	offspring
3. Metabolism	All living organisms require energy that they obtain while carrying out various chemical reactions. The sum of all chemical reactions that occur in an organism is known as metabolism.	Photosynthesis, cellular respiration, etc.
4. Homeostasis	A stable internal environment must be maintained. We know that changes in the external environment occur constantly (temperature, precipitation, etc.) However, organisms are capable of maintaining a stable internal environment, despite the changes occurring in the external environment. This is referred to as homeostasis.	Skin, fur on animals, etc.
5. Heredity	The basic unit of heredity is the gene. Genes are coded in a molecule known as DNA. The passing of traits from one generation to another is known as heredity.	Eye color, hair color, height, and stature.
6. Evolution	Changes in the environment can cause changes to the inherited characteristics of a species over time.	The size of birds’ beaks depends on the type of food they eat. If their environment or food options change, their beak size will adjust over time. If not, they may not survive.
7. Interdependence	Organisms are dependent on one another and their environment, which means they are interdependent.	Humans need plants to provide oxygen, so they can carry out cellular respiration. Plants need the products of cellular respiration, in order to carry out photosynthesis.

Click on the flash cards for a review of the terms in section 1.

Journal: Characteristics of Life, 25 points

Here are six living things: a person, an oak tree, a mushroom, an amoeba, seaweed, and a bacterium. What features do they all have in common? How do they differ? Use the Internet to aid your research.

Please submit your journal entry to the Characteristics of Life journal assignment link in Unit 1. For information on how this assignment will be graded, please visit the orientation.

Lab: The Scientific Method, 100 points

In this lab, you will be reviewing and applying the scientific method and learning how to convert units to the metric system.

Review the lab and following the procedures there. Download your lab report and fill it out as you move through the lab.

Submit your completed lab to the Lab: The Scientific Method assignment link for grading. For information on how this assignment will be graded, please visit the orientation.

The Scientific Method Lab Quiz, 20 points

It is now time to complete The Scientific Method Lab Quiz. Review your lab notes and report before completing the quiz.

The Nature of Science and Biology Quiz, 50 points

Congratulations on completing this section!  In this section you learned about:

• What biologists do.
• The scientific method.
• The characteristics of life.
• Unifying themes of biology.

Now it’s time to take the section quiz. Please make sure to check your understanding of the topics above before proceeding to the quiz.  After you have completed the quiz, continue with the unit.

Now go on to the next section.