Exploring and Classifying Life

1. 7th Grade Science- Chapter 1 (Glencoe Science) Exploring and Classifying Life

2. Section 1 What is science?

3. The Work of Science • Science is often described as an organized way of studying things and finding answers to questions. • Scientists find out things by asking questions. • There are many types of science (physics, life science, botany, zoology, etc.)

4. Critical Thinking • Critical thinking is the way you use skills to solve problems. (Skills like separating important and unimportant information, and identifying the problem.)

5. Solving Problems • Solving a problem requires organization. In science, this organization is known as the scientific method (SGFTADR). • SGFTADR stands for State the problem, Gather information, Form a hypothesis, Test the hypothesis, Analyze data, Draw conclusions, Report results.

6. State the Problem

7. Gather Information

8. Form a hypothesis (A hypothesis is a prediction that can be tested.)

9. Test the hypothesis (Note: In an experiment, the control is the standard to which the outcome is prepared. A variable is something in an experiment that can be changed. There should only be one variable in an experiment)

10. Analyze Data

11. Draw Conclusions

12. Report Results

13. Developing Theories • A scientific theory is an explanation of things or events based on scientific knowledge that is the result of many observations and experiments. If data collected from several experiments over a period of time supports the hypothesis, it can finally be called a theory. However, theories can change!

14. Laws • A scientific law is a statement about how things work in nature that seems to be true all the time. Laws are less likely to change than theories.

15. SI • The International System of Units, or SI, is what scientists use today. • Length – meter • Volume – liter • Mass – gram (1,000 kg = 1 tonne)

16. Don’t forget!!! • To prevent accidents, follow safety rules in the laboratory.

17. Section 2 Living Things

18. What are living things like? • Living and nonliving things have similarities. • Any living thing is called an organism. • Organisms differ in size, shape, behavior, food needs, and where they can be found. • However, all organisms have similar traits. The acronym to remember this is OREG&DR.

19. O • Living Things Are Organized • Organisms are made of cells, which are the smallest units of an organism that can carry on the functions of life.

20. R • Living Things Respond • A stimulus is something that causes a change. A response is the reaction to the stimulus. Homeostasis is an organism’s ability to keep the proper conditions inside themselves.

21. E • Living Things Use Energy • Most organisms get energy either directly or indirectly from the Sun.

22. G&D • Living Things Grow & Develop • Organisms take in raw materials, make more cells, and grow. Or, the cell itself can grow (like in a one-celled organism). Organisms change as they grow. The length or time an organism is expected to live is its lifespan.

23. R • Living Things Reproduce • Living things must reproduce to avoid extinction.

24. What do living things need? • All living things need raw materials and a place to live in order to survive. • An organism’s surroundings must provide for all of its needs. • Water is important for all living things. Water makes up 50% of all living things.

25. Section 3 Where does life come from?

26. Life Comes from Life • The idea that living things came from nonliving things is known as spontaneous generation. • Louis Pasteur, a French chemist, disproved spontaneous generation in the mid-1800s. He replaced it with the theory of biogenesis, which states that all living things come only from living things.

27. Visualizing the Origins of Life • 1668: Francesco Redi (meat, maggots) • 1745: John Needham (broth in sealed flasks) • 1768: LazzaroSpallanzani (tiny organisms from other tiny organisms) • 1859: Louis Pasteur (disproved spontaneous generation by boiling broth in S-necked flasks) • 1942: Alexander Oparin (no oxygen in early Earth) • 1953: Stanley Miller and Harold Urey (chemicals found in living things could be produced)

28. Section 4 How are living things classified?

29. Classification • Organisms are classified into groups. • Carolus Linnaeus came up with grouping organisms together based on their structure. This two-word naming system is called binomial nomenclature. This is the system we use today. The first word of the two words is the genus, the second is the species. (For example: Tursiopstruncatus is the scientific name for the bottle-nosed dolphin.)

30. Modern Classification • Phylogeny is the evolutionary history of an organism, or how it has changed. This is the basis for the classification of many organisms.

31. Order of Classification • Kingdom • Phylum • Class • Order • Family • Genus • Species

32. How do I remember that? Just remember this: King Phil Cut Off Fingers Gathering Sushi.

33. Something to Know About Species • Organisms that belong to the same species can mate and produce fertile offspring.

34. Scientific Names • Scientific names help avoid mistakes, classify organisms with similar evolutionary histories together, give descriptive information about the species, and allow information to be organized easily and efficiently.

35. Tools for Identifying Organisms • Tools for identifying organisms include field guides and dichotomous keys.

36. Did you understand what you read??? Test yourself! Questions

37. Section 1 Questions • How many variables should an experiment have? Why? • What is a theory based on? • Identify steps that should be followed when using scientific methods. • What SI unit would you use to measure the width of your classroom? • How is a theory different than a hypothesis?

38. Section 2 Questions • What are some stimuli living things respond to? (List both internal and external stimuli.) • Why is reproduction important? • What is the main source of energy used by most organisms? • List five traits most organisms have. • Why would you expect to see cells if you looked at a section of a mushroom cap under a microscope? • In order to survive, what things do most organisms need? • Why is homeostasis important to organisms?

39. Section 3 Questions • According to the theory of spontaneous generation, where do living things come from? • Compare and contrast spontaneous generation and biogenesis. • Learn more about the scientists in “Visualizing the Origins of Life.” Write a paragraph about each scientist, including how they contributed to the disproving of spontaneous generation.

40. Section 4 Questions • What information would a scientist use to determine an organism’s phylogeny? • What are four functions of scientific names? • What is the purpose of classification? • How did Carolus Linnaeus contribute to the classification of living things? • How can you identify a species using a dichotomous key? (Hint: You must first research dichotomous keys.) • Think Logically: Why can common names cause confusion? • Think Critically: Would you expect a field guide to have common names as well as scientific names? Why or why not?

41. Checking Concepts • What category of organisms can mate and produce fertile offspring? • Which of these is the closest relative of CanisLupis? (Quercus alba,Equus zebra, Felistigris, or Canisfamiliaris) • What is the source of energy for plants?What makes up more than 50 percent of all living things? • Who finally disproved the theory of spontaneous generation?

42. Cont. • What gas do some scientists think was missing from Earth’s early atmosphere? • What is the length of time an organism is expected to live called? • What is the part of an experiment that can be changed called? • What does the first word in a two-word naming system identify? • What SI unit is used to measure the volume of liquids?

43. That’s all! Next up: Cells – The Units of Life