CP Biology Name
HOMEWORK PACKET
LAB SKILLS DEVELOPMENT
Scientific methods
Name Class Date
1.1 What Is Science?
Scientific Methodology: The Heart of Science
The questions below refer to spontaneous generation, the idea that life can arise from nonliving matter. Spontaneous generation was accepted by many in the scientific community up until the mid-nineteenth century. A series of simple experiments tested the validity of this idea.
1. Evidence used to support spontaneous generation was the observation that foods over time become covered in maggots or fungal and bacterial growth. The inference behind spontaneous generation is that there is no “parent” organism. Write this inference as a hypothesis using an if–then sentence that suggests a way of testing it.
2. In 1668, Francesco Redi proposed a different hypothesis to explain the specific example of maggots that appear on spoiled food. He had observed that maggots appear on meat a few days after flies have been seen on the food. He inferred that the flies had left behind eggs too small to see. Redi’s experiment is shown below. What conclusion can you draw from Redi’s experiment?
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. In the late 1700s, Lazzaro Spallanzani designed a different experiment to show that life did not arise spontaneously from food. He inferred that some foods spoil because of growing populations of microorganisms. Fill in the information requested below.
Independent variable:
Dependent variable:
Controlled variables (identify three):
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4. Critics of Spallanzini said that he showed only that organisms cannot live without air. In 1859 Louis Pasteur designed an experiment to address that criticism, an experiment that reproduced Spallanzani’s results.
Draw in the third and final steps in the experiment. Use an arrow to show the path of travel of the microorganisms. Shade the broth in the flask(s) in which microorganisms grew.
5. How did Pasteur solve Spallanzani’s problem of limiting exposure to air?
6. What purpose did boiling the meat broth serve in both the Spallanzani and Pasteur experiments?
7. How do the Redi, Spallanzani, and Pasteur experiments disprove the hypothesis you wrote in Question 1?
Scientific Method Practice
______8. Who uses the scientific method?
a. everyone, to solve both scientific and non-scientific problems
b. only students
c. only doctors
d. only teachers
e. only research scientists
______9. Which of the following is true about a hypothesis?
a. it should be phrased as a question
b. it should be phrased as a possible answer to your original question
c. it should be made only after you analyze your experimental data
d. all of these
e. none of these
______10. Which of the following is the best definition of “controlled variables”?
a. factors which are used only in the control group
b. data collected during the course of an experiment
c. factors which are the same between your control and experimental groups
d. factors which are different between your control and experimental groups
_____11. Which of the following should you do after the conclusion of your experiment?
a. share your findings with others
b. consider repeating your experiment to confirm your results
c. think about sources of error in your experiment and consider revising your procedure and trying again.
d. all of these
e. none of these
_____ 12. What is the purpose of analyzing data collected during an experiment?
a. to make sure you wrote down all of the information correctly
b. to organize the data (including tables and graphs)
c. to use the information collected to draw conclusions
d. all of these
e. none of these
_____13. Which of the following is an example of collecting data?
a. Justin wondered if plant dyes could be taken out of plant leaves, flowers, and stems.
b. Susan said “If I fertilize my geranium plants, they will blossom.”
c. Angela’s experiment proved that earthworms move away from light.
d. Arthur noted that his basil plants were 10 cm higher after treatment with a fertilizer.
_____14. Suppose a student collected the following data during her experiment: 14cm,
16 cm, 18 cm. This is an example of:
a. qualitative data b. quantitative data
____15. In any experiment, how many experimental variables should be tested at a time?
a. an unlimited number b. 2-5 c. only 1 d. over 100
Identifying Steps of the Scientific Method
Use the lettered choices below to identify the steps of the scientific method below:
a. collect and analyze data d. design a controlled experiment
b. observe and ask questions e. infer and form a hypothesis
c. report the results to peers f. draw conclusions
______16. The scientist records the number of oranges each tree grows during the summer and calculates that the trees with fertilizer produced an average of 10 bushels while the trees without fertilizer produced 6 bushels of oranges. A graph of the data is made.
______17. A scientist wants to know whether orange trees need fertilizer in order to produce fruit. In order to learn more about the use of fertilizers on fruit trees, she read several articles in The North American Journal of Agriculture.
______18. The scientist thinks that fertilizer is necessary. She states that if orange trees need fertilizer to grow fruit, then trees given fertilizer will produce more oranges than trees without fertilizer.
______19. An experiment is designed in which 15 orange trees are given fertilizer. An equal number of trees are not given fertilizer.
______20. The scientist decides that the data have shown that fertilizer increases the number of oranges produced by a tree. She states that this hypothesis has been supported by the data.
______21. A journal article is written by the scientist so she can share information with others.
22. A scientist wants to know which of the three kinds of bird seed attract cardinals the best; sunflower seeds, thistle seeds, or corn. She states her hypothesis: Sunflower seeds will attract the most cardinals.
Write a prediction statement based upon this hypothesis. (Hint: (If your hypothesis Then this will happen when you do this…).
23. What is the experimental variable in the experiment described above?
24. What do you think were the controlled variables?
Read the following paragraph and answer the questions that follow. Read the questions carefully and think about the definitions for the terms you are asked to identify before you identify them.
A researcher has developed a new soap for acne that he believes will reduce the number of blemishes (pimples) in teenagers. He wants to determine if it is effective at reducing the number of blemishes when used two times a day. He obtains volunteers that have moderate to sever acne and begins his research.
The design of the experiment is as follows: The individuals are divided into 2 groups; each will be asked to wash their faces each morning and evening with the study soap provided. The are reminded not to use an other soaps or creams on their faces, they are asked not to use any makeup or perfumes on or near their faces for the duration of the study (6 weeks). The individuals are asked not to take any medicine for acne (like antibiotics, etc.) One group (group 1) will receive the soap with the acne medicine in it and one group (group 2) will receive the same soap without any acne medicine in it. The individuals will be checked in his office once per week for six weeks to determine if their skin has improved.
25. What is the researcher’s hypothesis?
26. What is the experimental variable?
27. Which group is the experimental group?
28. Which group is the control group?
29. List two controlled variables.
Time of visits(in weeks) / Number of blemishes for Group #1 / Number of blemishes for Group #2
0 / 30 / 26
1 / 26 / 24
2 / 22 / 32
3 / 14 / 30
4 / 8 / 28
5 / 6 / 24
6 / 3 / 26
30. Construct a line graph of the data presented above. Please be sure to title your graph, label your x and y axis, and create a key you’re your two lines on your graph.
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