Designing Scientific Investigations Answers

A student wants to answer the question “Does adding calcium powder to soil make pea plants grow faster?” She adds calcium powder to the soil of 12 plants and does not add it to the soil of a second group of 12 plants. She measures the growth of all of the plants in each group for a month. Which statement best summarizes the factors that need to be controlled in this experiment?

A zoology student is investigating whether it is true that the gender of turtles depends on the temperature at which the turtle eggs are kept before they hatch. He will test if turtle eggs incubated at 29–30 degrees Celsius produce females, and eggs at 24–26 degrees Celsius produce males. What is the independent variable?

During an investigation, Sam observes the number of hummingbirds that come to his large bird feeder at different times of day. He fills the feeder to the top the first day and counts the number of birds at 6 a.m., noon, and 6 p.m. over ten days. What are the independent and dependent variables in Sam’s investigation?

Which statement describes the dependent variable?

A scientist monitors the number of eggs in five duck nests in parks, five duck nests in zoos, and five duck nests in the wild during the spring and summer for three years. He makes a multiple line graph to plot and compare data for the three locations. Which question describes what the scientist is most likely testing?

Mei wants to study whether heart rate increases more during certain exercises than during others. She designs an experiment to test the heart rates of classmates in the morning and in the evening for three days, immediately after doing jumping jacks, doing push-ups, or running in place. What is the dependent variable in this experiment?

Choose the best scientific design to test the question “Which soil type results in the highest yield of tomatoes: clay soil or sandy soil?”

Repeating tests usually leads to

Choose the best experimental design to test the question “Does the gender of mice affect the time it takes to learn mazes?”

Carlo is wondering what causes plants to grow at different rates. Carlo’s hypothesis is “Plants will grow more when the day is longer.” To test his hypothesis, Carlo sets up an investigation that includes an experimental and control group. What factor would remain constant in the control group, but would change in the experimental group?