Scientific Method

A scientist performs an experiment to see if acids have an effect on the health of a particular type of plant. Three sets of plants were treated with acidic solutions of known pH while the control set was treated with a solution of neutral pH 7.Which is the best conclusion for this experiment?

• Acid has no effect on the health of this type of plant.
• B. High acidity is helpful to this type of plant.
• C. Low acidity is harmful to this type of plant.
• High acidity is harmful to this type of plant.

The graph below shows atmospheric carbon dioxide levels since the year 1880.Which of the following conclusions can be drawn from this graph

•  Atmospheric carbon dioxide levels are responsible for global temperature change.
•  Atmospheric carbon dioxide levels have been rising at about the same rate for the past century.
• Atmospheric carbon dioxide levels have remained the same over the past century.
•  Atmospheric carbon dioxide levels have been rising at an increasingly higher rate as the past century has progressed.

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NGSS.HS-ESS2-6

NGSS.HS-ESS3-5

A research group has discovered that damselflies, a type of dragonfly, are being infected by a particular type of aquatic protozoan. Both young and adult damselflies are not directly infected by the protozoan but contract the infection from the prey they eat. The graph shows the percentage of adult damselflies infected by protozoans during the summer and early fal

• Infection in embanked ponds increased during the sampling period.
• Protozoans were more common in creek-fed ponds than embanked ponds.
• Protozoans reproduce more quickly in embanked ponds than creek-fed ponds.
• Infection in creed-fed ponds remained constant throughout the sampling period.

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NGSS.MS-LS2-1

NGSS.MS-LS2-4

Carmen conducted an experiment to determine if listening to different types of music would affect a person’s pulse. Her hypothesis was that pulse rate would change with different types of music. Each person listened to seven different selections of music for 30 seconds each. Each person’s pulse was taken before the music and then after each 30-second interval of music. The pulses were taken again after the music selections were completed. Based on her experiment, Carmen concluded that a person’s pulse rate changed when the person listened to different types of music.  Which component is missing from Carmen’s experiment?

• a question
• a hypothesis
• a control group
• a description of the experiment

An osmosis investigation was conducted using chicken eggs to represent cells with semipermeable membranes. The mass of each egg was measured to determine how much water diffused into or out of the eggs. The eggs were first soaked in vinegar to dissolve the shell. Each egg was then placed in one of three different solutions for 24 hours. The table below shows the results of the investigation. Based on this experiment, which of the following should be inferred about cells with semipermeable membranes?

• Substances other than water may also cross the cell membrane.
• Substances other than water may block pores in the cell membrane.
•  Water enters the cell when placed in environments of high water concentration.
• Water leaves the cell when placed in environments with a low concentration of solutes

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NGSS.MS-LS2-1

NGSS.MS-LS1-2

In order to be accepted, a scientific theory must be

•  widely tested and supported by extensive data
•  based on the results of a single experiment
•  controversial and cause debate
•  in line with all previous historical ideas

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NGSS.HS-LS4-1

NGSS.HS-PS1-2

In an appropriately designed experiment, a scientist is able to test the effect of

•  a single variable
•  multiple variables
•  the hypothesis
•  scientific observations

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NGSS.MS-LS1-5

Which statement best expresses a basic scientific assumption?

• Interpretation of experimental results has provided explanations for all natural phenomena.
• If a conclusion is valid, similar investigations by other scientists should result in the same conclusion.
• For any conclusion to be valid, the design of the experiment requires that only two groups be compared.
• After a scientist formulates a conclusion based on an experiment, no further investigation is necessary.

Conclusions based on an experiment are most likely to be accepted when

• they are consistent with experimental data and observations
•  they are derived from investigations having many experimental variables
•  scientists agree that only one hypothesis has been tested
•  hypotheses are based on one experimental design

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NGSS.MS-LS2-4

NGSS.MS-PS1-2

An experiment was carried out to determine whether drinking caffeinated soda increases pulse rate. The pulse rates of two groups of people at rest were measured. Group A was then given caffeinated soda and group B was given caffeine-free soda. One hour after drinking the soda, the pulse rates were measured. The participants in the experiment were all the same age, and they were all given the same amount of soda. The dependent variable in this experiment is the

• type of soda given to each group
• amount of soda given to each group
•  pulse rate of each group
• age of participants in each group