Study Guide

Mild/Moderate Middle/Secondary Multi-Content:
Science
Sample Questions

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Competency 0031
Understand science and engineering practices and crosscutting concepts.

1. A scientist plants 100 bean seeds to investigate the effect of soil pH on growth rate and flowering. The seeds are planted in two large containers with 50 seeds in each container. The soil in one of the containers has a pH of 4, while the soil in the other container has a pH of 10. Which of the following changes to the experimental design would most improve the usefulness of the results?

  1. increasing the number of plants in each group to reduce the effects of individual variability
  2. limiting the dependent variable to either flowering or growth rate
  3. planting a group of seeds in soil with a neutral pH to serve as a control
  4. placing the seeds in individual pots so that they do not crowd each other
Enter to expand or collapse answer.Answer expanded
Correct Response: C. A control group is an important component of a well-designed experiment because it helps scientists accurately interpret experimental results. In this experiment, since one of the containers contains acidic soil (i.e., soil having a pH of 4) and one of the containers has basic soil (i.e., soil having a pH of 10), an appropriate control would be to include a container that has soil of neutral pH (i.e., soil having a pH of 7).

Competency 0032
Understand fundamental concepts of biology.

2. Plants of the pea family use which of the following strategies to obtain a portion of their nitrogen requirement?

  1. absorbing atmospheric nitrogen through the stomata in their leaves and stems
  2. breaking down amino acids found in decaying soil humus into elemental nitrogen
  3. hosting bacteria in their roots that transform gaseous nitrogen into useable nitrogen compounds
  4. taking in rainwater that contains dissolved elemental nitrogen through leaf pores
Enter to expand or collapse answer.Answer expanded
Correct Response: C. Although approximately 78% of the atmosphere is made up of nitrogen, that nitrogen is not in a form that is useable by most organisms. Many plants, including pea plants, have close biological relationships with bacteria that are able to use atmospheric nitrogen, and in the process of using it, they convert the nitrogen to a form useful to the host plant.

Competency 0033
Understand fundamental concepts of physical science.

3. The speed at which sound waves travel in warm air is different from the speed at which they travel in colder air. Which of the following explains why sound waves travel differently in warm air as opposed to cold air?

  1. In warmer air, sound waves travel more rapidly because of the greater kinetic energy of the air molecules.
  2. In colder air, sound waves are transmitted more rapidly due to the greater density of the air.
  3. In warmer air, sound waves propagate more slowly because they are disrupted by convection currents.
  4. In colder air, sound waves are transmitted more slowly due to the higher pressure of cool air masses.
Enter to expand or collapse answer.Answer expanded
Correct Response: A. Sound is transmitted as a disturbance of the medium in which it is traveling. The movement of the sound waves is due in part to the kinetic energy of the molecules of the conducting medium, in this case air. The molecules in warm air have greater kinetic energy than those in cooler air, and therefore allow the wave to travel at a greater velocity.

Competency 0034
Understand fundamental concepts of Earth and space science.

4. The polar front jet stream, which is at an elevation of approximately 7 km to 12 km above sea level, is located in which layer of the atmosphere?

  1. mesosphere
  2. troposphere
  3. stratosphere
  4. thermosphere
Enter to expand or collapse answer.Answer expanded
Correct Response: B. The polar front jet stream is located within the troposphere, which extends from Earth's surface to approximately 20 km above sea level.