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A scientific theory

• is used to prove hypotheses.

• is used to prove a scientific law.

• is simply a claim or guess by a scientist.

• is a well-supported, widely accepted explanation.

Robert Hooke saw the first cork cells in 1665. He also coined the word "cell" at the same time. During the next 150 years, scientists developed cell theory. They discovered cell organelles and described the cell as the basic unit of all life. One point of cell theory was NOT accepted until the early 1900's. That point was the cells give rise to other cells. For much of this time, many scientists still believed that cells just appeared. That idea was called spontaneous generation. People believed that living cells to develop from non-living things, like meat or soup.

Why did it take over 150 years for the scientific community to accept the last point of cell theory: cells give rise to other cells?

• Microscopes were inferior to those we use today.

• The scientific community did not continue to research cell theory.

• Spontaneous generation was supported by religious views of the day.

• Without refrigerators it was easy to believe spontaneous generation.

This is a timeline depicting the development of atomic ___________. What word should be used to fill in the blank? Support your choice with evidence.

• Law. At each interval on the timeline, scientists described the patterns they saw in both atomic and subatomic structure.

• Law. Scientists used observation, experimentation, and mathematical models to explain atomic stricter and the behavior of subatomic particles.

• Hypothesis. Scientists conducted experiments at each interval. They made educated guesses regarding atomic structure and then experimented to support or rejected the hypotheses.

• Theory. At each interval on the timeline, scientists made observations and conducted experiments to explain how atoms and/or subatomic particles behaved in order to determine atomic structure.

A scientific law is something we can use to make a specific, concrete prediction. For example, the law of gravitation states that masses will attract each other, and you will find that this is always the case.

However, it can also be used to make concrete statements about the properties of an object in the right conditions. For example, if a material were found that was NOT attracted to other objects with masses, we could say that

• the material is charged.

• the material has no mass.

• the material must be floating.

• the material has very little mass.

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Which geological features MOST LIKELY prompted the development of the theory of plate tectonics?

• river deltas

• glacier fields

• mountain ranges

• tropical rainforests

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- prediction

- can be supported

- cannot be proved or disproved

- tested with a controlled experiment

The list of terms BEST describes a

• hypothesis.

• law.

• theory.

• variable.

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Identify the scientific law from among the following statements.

• The book fell 1 meter in 0.5 seconds

• Gravity acts upon each object on the Earth.

• The velocity of the book is 2 meters/second.

• I believe that the book will fall faster outside rather than inside the building.

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A teacher has asked four students to state a scientific theory. Which student is correct?

• Antonio

• Boris

• Chandrelle

• Danielle

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Darwin observed how farmers and breeders produced many kinds of farm animals and plants. These plants and animals had traits that were desired by the farmers and breeders. He also noticed how the study of similar body structures and vestigial organs could add to the evidence of evolution. After performing several breeding experiments, he came to certain conclusions and formulated some theories. His theory of evolution and natural selection is the most accepted one.

What is the reason behind the acceptance of Darwin's theory?

• It is supported by practical evidence and examples.

• It is supported by its harmonizing with other views.

• It is based on the ideas of earlier hypothesis and laws.

• It is based on the practical example of Lamarck’s theory

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A __________ predicts overall natural events in general terms, while a __________ is a very specific prediction based on one circumstance.

• law; theory

• law; hypothesis

• theory; hypothesis

• hypothesis; theory