1. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The World of Life Science Section 1 Asking About Life Section 2 Scientific Methods Section 3 Scientific Models Section 4 Tools, Measurement, and Safety Introductory Chapter Table of Contents

2. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Asking About Life Introductory Chapter Explain the importance of asking questions in science. State examples of life science at work. List three ways life science is beneficial to living things. Objectives

3. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Asking About Life Introductory Chapter It All Starts with a Question Life Science is the study of living things. In your Own Backyard You can ask questions about familiar organisms. Touring the World The questions you ask about your neighborhood are just a sample of all the questions you could ask about the world.

4. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Asking About Life Introductory Chapter Life Scientists Who are life scientists? Anyone Women and Men from any cultural background can become life scientists. Anywhere Life scientists carry out investigations in laboratories, on farms, in forests, on the ocean floor––even in space! Anything Life scientists study any thing that is a live, or that used to be alive, that interests them.

5. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Asking About Life Introductory Chapter Why Ask Questions? Fighting Diseases Science has led to many life- saving discoveries, such as the vaccination for polio. Understanding Inherited Diseases By learning about how some diseases are inherited and how they affect people, scientists hope to find ways to prevent or cure these diseases.

6. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Asking About Life Introductory Chapter Why Ask Questions? continued Protecting the Environment Understanding how we affect the world around us is the first step in finding solutions to problems such as pollution and the extinction of wildlife.

7. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Scientific Methods Introductory Chapter Describe scientific methods. Determine the appropriate design of a controlled experiment. Use information in tables and graphs to analyze experimental results. Explain how scientific knowledge can change. Objectives

8. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Scientific Methods Introductory Chapter What Are Scientific Methods? Scientific methods are the ways in which scientists answer questions and solve problems.

9. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Scientific Methods Introductory Chapter Ask a Question Asking a question helps focus the purpose of the investigation. Scientists often ask a question after making an observation. For example, students observing deformed frogs might ask, “Could something in the water be causing the deformities?”

10. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Scientific Methods Introductory Chapter Make Observations Accurate Observations Any information that you gather through your senses is an observation. Scientist use standard tools and methods to make and record observations.

11. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Scientific Methods Introductory Chapter Form a Hypothesis A hypothesis is a possible explanation or answer to a question that is based on observation and can be tested. A statement of cause and effect that can be used to set up a test for a hypothesis is called a prediction.

12. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Scientific Methods Introductory Chapter A Hypothesis Makes Predictions

13. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Scientific Methods Introductory Chapter Test the Hypothesis Under Control A controlled experiment tests only one factor at a time and consists of a control group and one or more experimental groups.

14. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Scientific Methods Introductory Chapter Test the Hypothesis, continued Designing an Experiment Designing a good experiment requires planning and a consideration of all factors. Collecting Data Scientists keep clear, accurate, honest records of their data so that other scientists can repeat the experiment and verify the results.

15. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Scientific Methods Introductory Chapter Analyze the Results After they finish their tests, scientists must analyze the results. Analyzing the results helps scientists explain and focus on the effect of the variable.

16. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Scientific Methods Introductory Chapter Draw Conclusions Scientists must conclude if the results of their tests support the hypothesis. Proving that a hypothesis is not true can be as valuable as proving that it is true.

17. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Scientific Methods Introductory Chapter Communicate Results After finishing an investigation, scientists communicate their results. Sharing allows other scientists to repeat experiments to see if they get the same results. Sometimes, new data lead scientists to change their hypotheses.

18. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Scientific Methods Introductory Chapter

19. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Scientific Models Introductory Chapter Give examples of three types of models. Identify the benefits and limitations of models. Compare the ways that scientists use hypotheses, theories, and laws. Objectives

20. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Scientific Models Introductory Chapter Types of Scientific Models Physical Models Physical models, such as miniature volcanoes and steam engines, look like the thing that they model. Mathematical Models A mathematical model may be made up of numbers, equations, and other forms of data. Charts and graphs are examples of mathematical models.

21. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Scientific Models Introductory Chapter Types of Scientific Models, continued Conceptual Models Conceptual models are systems of ideas or comparisons of unfamiliar things with familiar things to help explain unfamiliar ideas.

22. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Scientific Models Introductory Chapter Mathematical Model: A Punnett Square The Punnett square helps scientists study the passing of traits from parents to offspring.

23. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Scientific Models Introductory Chapter Building Scientific Knowledge Scientific Theories An explanation that ties together many related observations, facts, and tested hypotheses is called a theory. Scientific Laws A scientific law is a statement of what will happen in a specific situation. A law tells you how things work. Scientific Change If new evidence challenges an accepted idea, scientists must reexamine the old evidence and reevaluate the old idea.

24. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Tools, Measurement, and Safety Bellringer Write an answer in your science journal to the following question: Why do you think scientists use tools such as graduated cylinders and stopwatches? Introductory Chapter

25. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Tools, Measurement, and Safety Introductory Chapter Give three examples of how life scientists use computers and technology. Describe three tools life scientists use or observe organisms. Explain the importance of the International System of Units, and give four examples of SI units. Objectives

26. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Tools, Measurement, and Safety Introductory Chapter Computers and Technology Technology is the application of sciences for practical purposes. Computers are used to create graphs, solve complex equations, and analyze and communicate data.

27. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Tools, Measurement, and Safety Introductory Chapter Tools for Seeing Compound Light Microscope is an instrument that uses two or more lenses to magnify small organisms. Electron Microscopes focuses a beam of electrons to magnify objects. Although electron microscopes produce clearer and more detailed images than light microscope, they cannot be used to observe living things.

28. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Tools, Measurement, and Safety Introductory Chapter Units of Measurement The International System of Units Begun by the French Academy of Sciences in the late 1700s, the SI is used by almost all countries in the world. All SI units are based on the number 10, which makes conversion from one unit to another easy.

29. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Tools, Measurement, and Safety Introductory Chapter

30. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Tools, Measurement, and Safety Introductory Chapter Measurement Length The basic unit of length in the SI is the meter. Area The measure of how much surface an object has. Use the following equation: area  length  width Volume The measure of the size of a body or region in three-dimensional space.

31. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Tools, Measurement, and Safety Introductory Chapter Measurement, continued Mass A measure of the amount of matter in an object. Temperature The measure of how hot (or cold) something is.

32. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Tools, Measurement, and Safety Introductory Chapter Measuring Temperature

33. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Tools, Measurement, and Safety Introductory Chapter

34. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Tools, Measurement, and Safety Introductory Chapter Safety Rules! Follow your teacher’s instructions. Read lab procedures carefully. Pay special attention to safety information.