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Chapter 1: What is Biology?

Difficulty Level: At Grade Created by: CK-12
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Contents: CK-12 Biology

Unit 1: Introduction to Life Science

  • Chapter 1: What is Biology?
  • Chapter 2: The Chemistry of Life

Unit 2: Cells

  • Chapter 3: Cellular Structure and Function
  • Chapter 4: Photosynthesis and Cellular Respiration
  • Chapter 5: The Cell Cycle, Mitosis, and Meiosis

Unit 3: Genetics

  • Chapter 6: Gregor Mendel and Genetics
  • Chapter 7: Molecular Genetics: From DNA to Proteins
  • Chapter 8: Human Genetics and Biotechnology

Unit 4: Evolution

  • Chapter 9: Life: From the First Organism Onward
  • Chapter 10: The Theory of Evolution

Unit 5: Ecology

  • Chapter 11: The Principles of Ecology
  • Chapter 12: Communities and Populations

Unit 6: Microorganisms and Fungi

  • Chapter 13: Microorganisms: Prokaryotes and Viruses
  • Chapter 14: Eukaryotes: Protists and Fungi

Unit 7: Plants

  • Chapter 15: Plant Evolution and Classification
  • Chapter 16: Plant Biology

Unit 8: Invertebrates

  • Chapter 17: Introduction to Animals
  • Chapter 18: From Sponges to Invertebrate Chordates

Unit 9: Vertebrates

  • Chapter 19: From Fish to Birds
  • Chapter 20: Mammals and Animal Behavior

Unit 10: Human Biology

  • Chapter 21: Introduction to the Human Body: Bones, Muscles, and Skin
  • Chapter 22: The Nervous and Endocrine Systems
  • Chapter 23: The Circulatory, Respiratory, Digestive, and Excretory Systems
  • Chapter 24: The Immune System and Disease
  • Chapter 25: Reproduction and Human Development

Biology Glossary

The Teacher's Edition (TE)

  • The CK-12 Biology Teacher's Edition complements CK-12's Biology FlexBook®. The TE comprises six strands: Teaching Strategies & Tips, Differentiated Instruction, Enrichment, Science Inquiry, Common Misconceptions, and Assessments.

Each unit and chapter will have a general overview. Each chapter section will also include an introduction and teaching strategies. The majority of content will be presented by individual lesson.

This Teacher's Edition will focus on eight subtopics for each lesson:

  1. Key Concept
  2. Lesson Objectives
  3. Lesson Vocabulary
  4. Check Your Understanding
  5. Teaching Strategies
  6. Reinforce and Review
  7. Points to Consider

Worksheets and Assessments

  • The CK-12 Biology Workbook complements CK-12's Biology FlexBook® and contains six worksheets for each lesson.
  • The CK-12 Biology Quizzes and Tests complements CK-12's Biology FlexBook® and contains one quiz per lesson, one chapter test, and one unit test.

Science Notebook

For a year's study of Biology, we recommend a science and/or lab notebook in which students may:

  • Answer the Check Your Understanding questions.
  • Answer/reflect on the Points to Consider questions.
  • Write additional questions about an upcoming lesson, chapter, or unit of study.
  • Draw pictures of living organisms and diagrams of life processes.
  • Take notes and define academic vocabulary.
  • Keep a record of pertinent web sites to access relevant information.
  • Write up lab activities.
  • Write up ideas for possible long-term projects.
  • Keep reflections on what they have learned.

Students should date each entry and refer back to their ideas earlier in the year, reflecting on their deepening understanding.

Teaching Strategies

Throughout the TE, we will provide numerous examples of strategies that can be used to make the content accessible to students. Many strategies and activities have been included as web site links, and we recommend that these be previewed before assigning to the students. Traditional examples of general teaching strategies, differentiated instruction, enrichment, science inquiry, and reinforcement strategies will be provided.

Teaching Strategies: General

  1. Appreciate what’s difficult for students, helping them develop scientific ways of thinking.
  2. Vary class activities, using a wide variety of resources to aid students in deepening their understanding of scientific issues.
  3. Give students opportunities to participate in scientific investigations to understand “doing science.”
  • Using Visuals

Use illustrations in the student edition as a tool for teaching content, exploring ideas, and probing students’ misunderstandings.

  • Building Science Skills

Have students apply higher-level thinking or other relevant skills as they relate to lesson content (e.g., predicting, forming hypotheses, drawing conclusions, interpreting data, observing, classifying, making inferences, comparing and contrasting, identifying cause and effect, analyzing). This might be achieved through a simple activity, answering questions, class discussion, and/or partner work.

  • Discussion

Stimulate class discussion of a topic. This could include scripted questions to ask the class, with expected or sample answers. The discussion tips should be specific and focused. For example, don’t write: “Discuss Darwin’s theory of evolution.” Instead, write: “Guide students in discussing why Darwin’s theory was not widely accepted in his own lifetime.” Ask: “How did Darwin’s theory of evolution conflict with prevailing views of living things?”

  • Demonstration

Do (and fully describe) an in-class demonstration to illustrate or explain a process, concept, etc. Keep in mind constraints on classroom time and resources. Include a concluding sentence or scripted question that relates the demonstration to the process or concept.

  • Activity

Have students do a simple hands-on activity that will help them better understand a topic or process. Explain fully how the activity is to be done. This could be a pencil-and-paper activity or other activity that does not involve materials, although readily available classroom materials could be used. Again, conclude with a sentence or question that ties the activity with the topic or process being studied.

Teaching Strategies: Differentiated Instruction

These strategies can be used for all three types of student populations that are typically addressed by DI (i.e., ELL, LPR, SN), but a particular population has been specified each time a strategy is used. The strategy can be tailored somewhat to that population, even if it’s only by referring to the population type in the strategy (e.g., “Pair English language learners with native speakers of English”).

  • KWL

Have students make a KWL chart, where K = Know, W = Want to Know, and L = Learned. Students should fill in the K and W columns before reading and the L column after reading a particular passage or lesson.

  • Cloze Prompts

Give students cloze sentences (basically, fill-in-the-blank sentences) about important lesson concepts. Students are instructed to fill in the missing words as they read the lesson.

  • Gallery Walk

Divide the class into groups and have the groups walk around the room to read and discuss posted questions or topics (each on a large sheet of paper). Each group (using a different color pen) answers the questions or writes comments about the topics. They also read and respond to answers/comments written by other groups. This is followed by discussing the answers/comments with the class, reviewing misunderstandings they reveal, or by groups summarizing what they know about one or more questions/topics.

  • Think-Pair-Share

Assign questions or topics to individual students to think about. Pair ELL students with native speakers and LPR students with more proficient readers to work together on answering the questions or discussing the topics.

  • Frayer Model

Assign this vocabulary strategy, which involves students drawing a large box and dividing it into four parts labeled “Definition,” “Drawing,” “Example,” and “Non-example.” Assign students a vocabulary word and tell them to fill in each part of the box for that word.

  • Cluster Diagram

Have individual students, pairs, groups, or the class as a whole make a cluster diagram organizing lesson concepts.

  • Concept Map

Have individual students, pairs, groups, or the class as a whole make a concept map organizing lesson concepts.

  • Venn Diagram

Have individual students, pairs, groups, or the class as a whole make a Venn diagram organizing lesson concepts.

  • Compare/Contrast Table

Have individual students, pairs, groups, or the class as a whole make a compare/contrast table for specific lesson concepts, processes, etc. (e.g., photosynthesis and cellular respiration; mitosis and meiosis). You may need to provide the column and row headings for the table.

  • Cycle Diagram

Have individual students, pairs, groups, or the class as a whole make a cycle diagram to show the steps in a cyclical process (e.g., life cycle of amphibians).

  • Flow Chart

Have individual students, pairs, groups, or the class as a whole make a flow chart to show the steps in a process (e.g., photosynthesis).

  • Main Ideas/Details Chart

Have students divide a sheet of paper in half, on the left side write the main ideas from a passage or lesson (skipping several lines between the main ideas). On the right side, students are instructed to fill in important details about each main idea as they read.

  • Word Wall

Post lesson vocabulary words and their definitions, examples, etc., on a bulletin board or wall. Refer students to the word wall as they study lesson content.

Teaching Strategies: Enrichment

Although online and/or library research is always an option for enrichment, it tends to be overused. Avoid it unless it is really relevant and likely to be helpful for the other students in the class. Whatever students are assigned to do, they should be given a chance to share their work with the class through an informal oral presentation, a written report, etc. In some cases (e.g., making a board game or crossword puzzle), the product can be used by the class to reinforce or review lesson content.

  • Research a Topic
  • Present a Role-Play
  • Teach a Topic
  • Create a Video
  • Create a Poster
  • Debate an Issue
  • Interview an Expert
  • Create a Model
  • Demonstrate a Process
  • Take a Survey
  • Write an Essay
  • Make a Board Game
  • Make a Crossword Puzzle
  • Create a Web Site
  • Make a Diagram
  • Make a Diorama
  • Make a Display
  • Write a Research Proposal
  • Make a Video
  • Write a Rap (Song)
  • Present a PowerPoint Show
  • Lead a Discussion

Teaching Strategies: Science Inquiry

These strategies should get students involved in thinking or acting like a scientist. They should help the students learn lesson content by encouraging them to be actively engaged in scientific thinking and/or using scientific methods.

  • Ask a Research Question: e.g., based on hypothetical observations.
  • Formulate a Hypothesis: e.g., based on a research question. Must be specific and testable; could also ask students to describe data that would support or disprove the hypothesis.
  • Develop a Research Plan: e.g., to test a specific hypothesis. Could focus on types of variables, controls, etc.
  • Analyze Data: Data could be in a graph or table that is provided in the SE or TE or students could find the data online.
  • Solve a Problem: requiring application of lesson concepts, procedures, etc.

Reinforcement Activity

In addition to online quizzes, this could be a quick teacher-directed activity or something students do alone or in pairs to make sure they understand lesson content. It should probably be aimed at the average to below-average students in the class, though reinforcement activities are important for all students. Some suggestions are listed below. The goal is to reveal to the teacher or to the students themselves what they know and what they still don’t understand. The activity should include a sentence suggesting a way for students to learn what they don’t know (e.g., “Find definitions in the FlexBook® textbook of any vocabulary words you did not know.”).

  • Take an Online Quiz: Have students track their own level of mastery of concepts as measured by quizzes. Additionally, you could have students take the quiz before and after teaching the material and have them track their growth.
  • Make Flashcards: This activity could be used for boldface vocabulary words or important concepts; have students use the flashcards to quiz a partner.
  • Label a Drawing: The drawing could be art from the SE with the labels deleted.
  • Outline the Lesson: This could be done with a partner or as a class using an overhead projector.
  • Ask Questions: Each student turns in a question on an index card. Then, the teacher answers or reviews material relevant to those questions that are asked most frequently.
  • List and Discuss: Students make a list of something (e.g., reproductive isolating mechanisms), and then partners compare and discuss their lists.
  • Use Vocabulary: Students use the lesson vocabulary words in sentences or a brief paragraph.
  • Make a Quiz: Students write a few fill-in, matching, or true/false questions and then use them to quiz a partner.
  • Make a Drawing: Students create a simple sketch to demonstrate comprehension of a process (e.g., cell division).
  • Complete a Chart: Students complete missing parts of a diagram or fill in cells of a table that have missing information.

Check Your Understanding

This section includes questions related to previously presented information that the authors consider important for the student to have access to the information in the current lesson.

Points to Consider

Questions in this section serve as a segue into the next lesson (or chapter). Ask students to read the Points to Consider at the end of the lesson in their FlexBook® textbook. They can be answered individually or as an opening to lead a class discussion. Use these questions to assess student understanding and misconceptions before beginning the next unit of study.


CK-12 wishes to thank Jean Brainard, Ph.D., Doris Kraus, Ph.D., Margaret Lynch, Ph.D., and Douglas Wilkin, Ph.D. for their contributions.

Image copyright Kjpargeter, 2014. www.shutterstock.com. Used under license from Shutterstock.com.

What is Biology?


Lesson 1.1: Science and the Natural World

1.1.1 Goal of Science

  • Nature Can Be Understood
  • Scientific Ideas Can Change
  • Scientific Knowledge Can Withstand the Test of Time
  • Science Cannot Answer All Questions

1.1.2 The Scientific Method

  • Making Observations
  • Asking a Question
  • Forming a Hypothesis
  • Testing the Hypothesis
  • Drawing Conclusions
  • Communicating Results

1.1.3 Experiments

  • KQED: Medicine From the Ocean Floor
  • Variables
  • Sample Size and Repetition

1.1.4 Other Types of Scientific Investigations

  • Natural Studies
  • Modeling

1.1.5 Scientific Theories

1.1.6 KQED: Bio-Inspiration: Nature as Muse

Lesson 1.2: Biology: The Study of Life

1.2.1 Characteristics of Life

  • Response to the Environment
  • Growth and Development
  • Reproduction
  • Keeping Things Constant
  • Complex Chemistry
  • Cells

1.2.2 Unifying Principles of Biology

  • The Cell Theory
  • The Gene Theory
  • Homeostasis
  • Evolution

1.2.3 Interdependence of Living Things

  • Symbiosis
  • Competition
  • Levels of Organization
  • Diversity of Life

1.2.4 Evolution of Life

  • Darwin and the Theory of Evolution
  • Evolutionary Theory After Darwin
  • Misconceptions About Evolution

Pacing the Lessons

Use the Class Periods per Lesson table below as a guide for the time required to teach the lessons of this chapter.

Lesson Number of Class Periods
1.1 Science and the Natural World 3
1.2 Biology: The Study of Life 2
Assessment 1
  • Class periods are assumed to be 60 minutes long.

Online Resources

See the following Web sites for appropriate laboratory activities:

The Web sites below may also be helpful for this lesson and other lessons throughout the text. They provide additional background and ideas for classroom activities.

Chapter Outline

Chapter Summary

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