Nature of Science

At one point in time, many people thought disease was caused by fate or by incorrect behavior. Following the invention of the microscope, bacteria were discovered. After this, a new theory of what causes disease arose that was known as the germ theory.  Why was the original theory modified? 

• It quickly became obvious that germs cause disease.
• The person who invented the microscope became ill.
• New evidence prompted revision to the original ideas.
• The proponents of the germ theory had political power.

Newton’s third law of motion states that for every action there is an equal and opposite reaction. How does this law differ from a theory?

• A theory explains a set of well tested observations; a law describes a pattern in nature.
• Laws can be changed with the addition of new evidence but theories cannot.
• A law explains a pattern in nature in more detail than a theory. 
• Theories are based on more evidence than laws.

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In which statement does the word theory mean scientific theory?

• In theory, the experiment will work as planned. 
• She has a theory about why the storm arrived later than predicted. 
• The atomic theory explains that material objects are made up of atoms. 
• The doctor’s prescription for curing a cold is based on his best theory or guess. 

The theory of plate tectonics states that Earth’s crust is made of sections that move. Which of the following is NOT evidence that can be used to support the theory of plate tectonics?

• The sea floor is spreading apart from mid-ocean rifts.
• Mountains push up where two plates bump into each other.
• The same species of bird is found in North America and South America.
• The continents look as if they fit together like pieces of a jigsaw puzzle.

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Why is it important that scientists modify scientific theories when important new information is discovered?

• to confuse other scientists
• to keep the theory interesting and fresh
• to keep the theory as accurate and effective as possible
• to make sure the general public does not understand the theory

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Joe tells Mai his theory about why sea turtles nest on the beach instead of in the ocean. He says, “The turtle eggs would sink to the bottom of the ocean, and the baby turtles would drown.” Joe says his uncle is a fisherman, who told Joe this information. Mai tells Joe that his theory is not scientific. Which explanation supports Mai’s evaluation of Joe’s theory?

• Joe’s idea is already a scientific law. 
• Joe’s idea is not supported by scientific evidence. 
• Joe’s idea is a good guess that can be tested by experiments. 
• Joe’s idea accurately explains why sea turtles nest on the beach. 

 A biologist is investigating the effects of growth hormone on the rate of metamorphosis in butterflies. Which of the following methods of investigation would work best for the biologist investigating any possible effects?

• models
• controlled experiments
• systematic observations
• random sampling of populations

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Eduardo is a conservation biologist. He needs to develop a plan to preserve wetlands. He begins his project by studying the data in the following chart. How is Eduardo using scientific methods in developing a plan?

• He is analyzing data about causes and effects.
• He is analyzing a hypothesis about causes and effects.
• He is proposing an experiment about causes and effects.
• He is using intuition to determine causes and effects.

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Scientists discuss and debate experimental results and possible explanations in studying phenomena. Which best explains why scientists debate while searching for explanations?

• because debating helps scientists focus on empirical evidence, analyzing both the strengths and weaknesses of the evidence
• because debating helps the scientific community to present interesting and exciting science to the public
• because debating gives scientists an opportunity to express their feelings and opinions about the subject
• because every scientist wants to find an accurate explanation and disprove others’ explanations

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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
• a skin cancer survivor’s recollection that he had a bad sunburn as a child
• data demonstrating a relationship between amount of sun exposure and incidences of skin cancer
• an advertisement for a sun block product that claims it protects skin for ultraviolet rays

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