Variables quiz

A student constructs several terrariums to grow plants. Each terrarium is exposed to a different amount of sunlight each day. In order to determine the ideal amount of sunlight for best plant growth, which of the following variables must be held constant?

• growth rate

• amount of sunlight received

• type of plant

A student hypothesizes "If green algae is exposed to blue light, then it will grow faster than with other colors of light." To test his hypothesis, the student should design an experiment with which independent variable?

• color of light

• amount of light per day

• color of algae

Sandy is conducting an investigation to find out which dog food brand her dog likes best. She will set out three dishes with the same amount of dog foods from different brands. She will then measure the amount of food eaten to determine her dog's preference. Which is the dependent variable in his investigation?

• color of the dog's dish

• amount of food eaten

• the type of food given

Camren designed an experiment to determine which type of soil absorbs the most water. To ensure that the experiment results in valid data, certain variables need to be controlled. To do so, each container must

• contain the same amount of soil

• contain soil from the same place

• be tested by the same person

In an experiment, the variable that does not change in order to ensure valid data is

• controlled variable

• dependent variable

• independent variable

You design an experiment to test the effect of temperature on bacterial growth. You use three bacteria cultures under three heat lamps at different temperatures. What is the growth of bacteria be in this experiment?

• controlled variable

• dependent variable

• independent variable

A student plans to conduct an experiment to determine how a change in the pH of water affects the population growth rate of algae. To ensure that her experimental data are valid, she should

• vary the temperature

• hold the acidity constant

• use the same species of algae

The variable that is measured or observed as data is

• controlled variable

• dependent variable

• independent variable

In an experiment about growth, some snap dragon seeds were placed in dishes lined with moist paper towels at differing temperatures. Which of these is the independent variable in this experiment?

• the number of sprouts

• the type of seed

• the temperature