Science

The atomic theory has been revised over time. John Dalton described the atom as a solid sphere while a later theorist, Ernest Rutherford, developed a different model. Why has the atomic theory changed during the last several hundred years?

• The new method is more efficient at developing theories
• The atom has changed & new theories reflect these changes
  
• As new discoveries are made, existing theories, are revised
  
• The splitting of the atom created the need for a new theory

Artifacts from a Seminole tribe include a carved stone that was used as an ax head. The description of this artifact explains that an ax head could have taken many hours to make. Why does it take less time to make an ax head today than it did in ancient times?

• Axes are now made out of steel instead of rock
  
• There are more people today to work in manufacturing.
• the size and design of the ax head have changed
• Machines can be used in the manufacturing process
  

Tycho Brahe (1546-1601) was a Danish astronomer who observed the planets and stars without the benefit of a telescope. He kept records of planetary motion. His assistant, Johannes Kepler, used these records to formulate his three laws, which accurately predicted planetary motion. What does this suggest is the most important aspect of scientific study?

• Control over the variables of interest
  
• Ability to make observations and accurately record data
  
• Access to modern equipment and research methods
  
• Enough time to conduct a study & the amount of data recorded

A cellular phone company tested its phones for safe levels of radiation. They repeated the test 1,000 times. The company then hired a team of independent researchers to replicate the tests. Which statement explains why the company hired a team of researchers to replicate their tests?

• The company is only repeating part of the test.
  
• The company repeated the test to many times to be valid.
• If results can be replicated, they are likely to be valid.

After a scientific investigation, why is it important for the class to discuss all the results?

• It allows changing data so that it matches the hypothesis.
  
• It allows students to better understand method & conclusions
  
• It allows to select the best data and discard the rest.
  
• It allows students to find errors and change results.

As new info is discovered, theories change. Old theories can be revised. Why is this necessary?

• The process allows for an understanding of the world.
  
• New scientists need to get credit for their ideas.
  
• Old theories are found on old technology

Jason states the following prediction: “As the air temperature increases, the air in a balloon will expand, increasing the circumference if the balloon.” Which of the following is the outcome variable (dependent variable) for an experiment designed to test Jason’s prediction?

• The change in the circumference of the balloon.
  
• The material from which the balloon is made.
  
• How fast the balloon expands
  
• The difference in air temperature

Unprotected exposure to the sun’s rays is a factor in the development of skin cancer. Which of the following is an example of empirical evidence that supports this hypothesis?

• a model of a skin cell showing where DNA is in the cell.
  
• an ad for sun block that claims it protects against UV rays.
• a survivor remembering that he had a bad sunburn as a child.
  
• data showing sun exposure & incidences of skin cancer.
  

Antoine Lavoisier heated various substances and showed that the total mass of the starting materials was equal to the total mass of the products in a chemical reaction. His and other scientists’ observations led to the Law of Conservation of Mass which states that matter cannot be created or destroyed but changed from one form to another. Justify why his work led to a law instead of a theory.

• He collected data that supported his hypothesis.
  
• He described the relationship between the masses
  
• He explained how his observations provided evidence
  
• He provided a well-supported & widely accepted explanation

You want to determine if a new diet medication will help rats to lose weight. What factors should you keep the same throughout the experiment for both sets of rats?

• The type of rats and the diet medication
  
• The type of rats and the food they eat
  
• The rat’s weight and the food they eat
• the rats' weight and diet medication