9/2 Per 2 Warm-Up

An experiment is performed on plants to see how different liquids affect plant growth. Each plant in the experiment is given a different liquid; water, apple juice, or milk. Each plant has the same amount of soil, sunlight, and listens to the same music. In this investigation, the independent variable is ...

• The type of plant
• The amount of sunlight
• The type of music
• The type of liquid

In 1897, Joseph Thomson discovered that atoms contain electrons. He proposed a change in the atomic theory of that time, and the theory was modified because of his discovery. Since Thomson’s discovery, atomic theory has been further modified. What is the best explanation for why scientific theories are modified?

• Theories more than ten years old are usually out of date.

• Scientists want to prove that the work of other scientists is wrong.

• New evidence that supports a revision prompts scientists to modify earlier theories.

• So much information is available today that it is harder to focus research and disprove theories.

Natalie is using a three-dimensional representation to study the parts of the human heart. Isaiah is working in a laboratory to test the hypothesis that plants grow taller in green light than in white light. Which of the following best

compares their activities?

• Natalie is conducting a scientific investigation, and Isaiah is not.

• Natalie is not conducting a scientific investigation, and Isaiah is.

• Natalie is conducting an experiment, and Isaiah is conducting a field study.

• Natalie is investigating a scientific model, and Isaiah is conducting

  an experiment.

Jacob conducted an investigation to determine the effect of acid on different types of rocks. He found that the data he collected do not support his hypothesis. Why would Jacob's hypothesis still have some value?

• It might lead to the development of new investigations.

• It demonstrates that Jacob needs more practice investigating.

• It might encourage Jacob to investigate the effect of bases instead.

• It shows that Jacob's investigation could have been better planned.