Sci Method/Eng Design

This part of the experiment serves as a basis of comparison; the one variable being tested has been omitted. 

• experimental group
• control group
• data
• variables

A possible explanation to a problem that has not yet been tested. 

• data
• theory
• hypothesis
• fact

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

A student wants to test the effects of type of exercise on heart rate.  What is the dependent variable?

• heart rate
• type of exercise
• amount of exercise
• time of day exercise occurs

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, what are the controlled variables?

• Type of plant, amount of music, and sunlight
• Water, apple juice, milk
• Plant growth

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.

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.

Christopher set up six tanks with equal volumes of 20 ℃ water. Three of the tanks contained water with a high salt content of 30 parts per thousand and three contained water with no salt. Christopher added an equal amount of green algae to each tank. He allowed the algae to grow in the tanks for two weeks. Then, he measured the amount of algae in each tank. Identify the question that Christopher’s experiment can best answer.

• Is the growth of algae affected by the temperature?

• Do algae grown in water with a high salt content release more oxygen than an equal amount of algae grown in water without salt?

• Do algae grow more in water with high salt content than in water without salt?

When experimenting with the growth of a plant, a scientist uses three (of the same type of) plants, two different fertilizers, equal light, and equal water. The fact that we kept the light, plant, and water the same in each experiment are examples of ____________.

• an dependent variable
• an independent variable
• a control
• constants