Scientific Investigation: SOL 2008

A student constructs several terrariums like the one shown. Each terrarium is exposed to a different amount of sunlight each day. In order to determine the ideal amount of sunlight, which of the following variables must be

held constant?

• Type of plants

• Growth rate of plants

• Wavelengths of sunlight

• Amount of sunlight received

As part of an experiment to measure decomposition rates of different materials, students put food scraps from the cafeteria in compost bin A and leaves and grass clippings in compost bin B for six weeks. Students in first period measured the temperature in bin A, and students in sixth period measured the temperature in bin B. What is the greatest error in the students’ experimental design?

• There are too many uncontrolled variables in the experiment.

• Temperature is the only dependent variable in the experiment.

• The materials chosen decompose too rapidly.

• The students put equal masses of materials in each bin.

Scientists are using genetic engineering to develop a wheat crop that is resistant to a particular kind of moth. How would they determine if the plants are moth-resistant?

• Determine the length of the moth reproductive cycle in normal wheat.

• Determine whether moths in test wheat can be controlled with chemical sprays.

• Monitor numbers of moth species infesting normal wheat.

• Monitor moth populations in fields planted with test and normal wheat.

The diagram shows a setup for a plant investigation. Which variable is most likely being tested?

• Hours of light exposure

• Plant species

• Soil volume

• Soil pH

Twenty cuttings were taken from one plant and planted in four containers of sand. Two containers had a pH of 6.0, and two had a pH of 8.0. When the cuttings matured, all of those grown in a pH of 6.0 had pink flowers, and all of those grown in a pH of 8.0 had blue flowers. One explanation for these results is that the sand at one pH contained a dye that changed the flower color. The best alternative explanation for these results is that —

• the difference in pH caused the genes for flower color to be expressed differently

• a mutation occurred in the plant before the cuttings were taken and causedthe difference

• by mistake, the scientist took some cuttings from the wrong plant

• by random chance, different flower colors developed on the plants grown at different pH

A student hypothesizes that green algae will grow fastest when exposed to blue light. To test this hypothesis, the student should design an experiment with which independent variable?

• Color of algae

• Rate of algae growth

• Color of light that algae are exposed to

• Amount of time per day that algae are exposed to light

The graphs show the results of two separate experiments on the same species of plant. Students now want to determine how the use of rainwater or bottled water affects the growth of this plant. Which conditions should be used for optimal growth as the two water types are tested?

• 20°C, 10 mL/day

• 25°C, 35 mL/day

• 30°C, 45 mL/day

• 35°C, 20 mL/day

Students in a biology class thought that salt water would affect the movements of planaria. They put 25 planaria in salt water and recorded their observations. Which flaw was present in the design of their experiment?

• There was no hypothesis.

• There was no control.

• The sample was too big.

• The procedure was too complicated.

Which set of materials would be best to use to prepare a wet mount slide of onion skin cells?

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These three samples from the same live culture were all viewed at the same magnification. Which conclusion is best supported by the observation of these three samples?

• The bacterial culture was unaffected by the chemical agent.

• The sampling techniques used did not produce accurate data.

• The culture became contaminated by airborne bacteria during the initial sampling.

• The culture included some bacteria that were resistant to the chemical agent.