Study Guide

Middle School Education: Science
Sample Questions

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Competency 0001
Understand the practices of scientific inquiry and engineering design.

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 part of a well-designed experiment because it helps scientists accurately interpret results. In this experiment, since one of the containers has 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 0002
Understand crosscutting concepts in the sciences and engineering.

2. In working out the theory of evolution, Charles Darwin was strongly influenced by which of the following developments in the sciences?

  1. the hypothesis that Earth had changed gradually over long periods of time
  2. the discovery that cells are the basic unit of living organisms
  3. the recognition that Earth's crust is composed of shifting tectonic plates
  4. the discovery that ancient humans lived in Africa millions of years ago
Enter to expand or collapse answer.Answer expanded
Correct Response: A. Darwin's theory of evolution by natural selection requires a long time frame over which to work. The work of two geologists, James Hutton and Charles Lyell, suggested that Earth had changed gradually over long periods of time, supporting Darwin's theory.

Competency 0003
Understand the relationships between science, technology, and human activity in a global context.

3. In which of the following scenarios does the U.S. government most directly affect the work of scientists?

  1. The Food and Drug Administration evaluates the efficacy of a new medical device.
  2. Politicians running for office debate the potential risks to humanity of global warming.
  3. The governor of a large state announces new energy conservation measures for public buildings.
  4. Congress votes to support increased funding for research at the National Institutes of Health.
Enter to expand or collapse answer.Answer expanded
Correct Response: D. Government funding for research influences the work of scientists by encouraging them to work in funded areas of science and by providing funds for scientists to continue their work.

Competency 0004
Understand the properties of matter.

4. Which of the following elements is the most electronegative?

  1. hydrogen
  2. fluorine
  3. radon
  4. francium
Enter to expand or collapse answer.Answer expanded
Correct Response: B. The electronegativity of elements in the periodic table tends to increase from bottom to top within a group and from left to right across a period. Of the given elements, fluorine is in the uppermost position on the right-hand side of the periodic table.

Competency 0005
Understand physical and chemical changes of matter.

5. Use the balanced chemical equation below to answer the question that follows.

CaCO3(s) → CaO(s) + CO2(g)

What is the mass of calcium oxide (CaO) that is produced when 80.0 g of calcium carbonate (CaCO3) is heated and decomposes completely?

  1. 44.8 g
  2. 47.7 g
  3. 65.9 g
  4. 70.2 g
Enter to expand or collapse answer.Answer expanded
Correct Response: A. Since the reaction is already written in balanced form, one mole of CaO is produced for each mole of CaCO3 that reacts. The molecular weight of CaCO3 is the sum of the atomic weights of the atoms in CaCO3. The molecular weight of CaCO3 is 1(40.1 amu) + 1(12.01 amu) + 3(16.00 amu) = 100.1 amu. This means that CaCO3 has a mass of 100.1 g per mole. Therefore, 80.0 g of CaCO3 represents 0.799 mole of CaCO3 and must produce 0.799 mole of CaO. CaO has a molecular weight of 1(40.1 amu) + 1(16.00 amu) = 56.1 amu, and 0.799 mole of CaO has a mass of (0.799) (56.1), or 44.8 g.

Competency 0006
Understand the characteristics of energy and energy transformations.

6. Which of the electric circuits shown below will have the two brightest lights?







Enter to expand or collapse answer.Answer expanded
Correct Response: C. The brightness of an electric lamp is related to the amount of current through the lamp. Current in a circuit is directly proportional to voltage and inversely proportional to resistance. The circuits in responses A and C have a voltage of 3 V since they each have two 1.5 V cells in series. The difference between these two circuits is that in response A the lamps are in series, and in response C the lamps are parallel. Two resistances in series have a greater total resistance than the same two resistances in parallel.

Competency 0007
Understand the properties and principles of force and motion.

7. A 10 kg mass is suspended by two cables. In which of the following situations will the tension in the cable labeled X be the greatest?










Enter to expand or collapse answer.Answer expanded
Correct Response: B. In response D, the mass is supported symmetrically by two cables of equal length. The two cables must share the load equally. If the mass were to be supported by a single vertical cable and hang straight down (not shown), the cable would support all of the mass. Response B is closest to this situation and therefore has the greatest tension.

Competency 0008
Understand the characteristics and properties of mechanical and electromagnetic waves.

8. 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 0009
Understand the characteristics of living organisms.

9. The folding of the internal membrane of the mitochondria serves which of the following purposes?

  1. increasing the number of separate compartments in which proteins can be assembled
  2. increasing the capacity to filter waste products produced during the process of cellular respiration
  3. increasing the capacity to absorb enzymes needed to regulate cell division
  4. increasing the surface area over which energy-releasing chemical reactions take place
Enter to expand or collapse answer.Answer expanded
Correct Response: D. Many of the reactions involved in cellular respiration occur on the membranes of mitochondria. The folding of the internal membrane serves to increase its surface area, thereby providing more surface over which reactions can take place.

Competency 0010
Understand reproduction, heredity, and biological classification.

10. In which of the following situations would changes in a population's gene frequency be most likely to result in the development of a new species?

  1. A small population of a species of rodent is isolated permanently from the rest of its species by a natural disaster.
  2. A small population of a migratory species of caribou is substantially reduced by predators during a very cold winter.
  3. A population of an invasive weed species spreads along highways after being accidentally introduced.
  4. A population of a species of insect experiences rapid population growth during an unusually warm summer.
Enter to expand or collapse answer.Answer expanded
Correct Response: A. Geographic isolation of a species separates the species reproductively from other members of the species. This situation can result in the development of a new species because the isolated population takes a different evolutionary path from the main population due to genetic drift and differences in environmental pressures.

Competency 0011
Understand the interactions of organisms with their environments.

11. 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 into a form useful to the host plant.

Competency 0012
Understand Earth's history and the processes that shape and change its geosphere.

12. The conclusion that Earth's outer core is liquid is based on evidence obtained from the:

  1. characteristics of minerals retrieved from deep-ocean drilling.
  2. pattern of changes in Earth's magnetic field recorded over the past century.
  3. composition of igneous rocks from major volcanic eruptions.
  4. behavior of seismic waves as they travel through Earth's interior.
Enter to expand or collapse answer.Answer expanded
Correct Response: D. Since seismic waves behave differently in different materials, the behavior of the waves can be used to deduce geologic structure. The behavior of these waves indicates that Earth's outer core is liquid.

Competency 0013
Understand Earth's hydrosphere, atmosphere, weather, and climate.

13. Which of the following factors is primarily responsible for the worldwide change in sea level that has occurred in the past 15,000 years?

  1. thermal expansion of the oceans
  2. tectonic uplift of continental shelves
  3. isostatic uplift of coastal regions
  4. melting of continental glaciers
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Correct Response: D. Sea level has been rising at a slow rate for approximately 15,000 years, and over the past 100 years this rise has been accelerating. The change in sea level over the past 15,000 years has been due primarily to the melting and retreating of continental glaciers.

Competency 0014
Understand the composition and structure of the universe.

14. Use the diagram below to answer the question that follows.

The orbit of the moon is inclined 5 degrees from the plane that contains the sun and Earth. The moon is below the Earth-sun plane in the parts of the moon's orbit indicated by a dashed line in the diagram. Given the moon's inclined orbit, a solar eclipse would most likely occur in which of the positions shown in the diagram?

  1. position 1
  2. position 2
  3. position 3
  4. position 4
Enter to expand or collapse answer.Answer expanded
Correct Response: C. The moon will cast its shadow on Earth, producing a solar eclipse when the moon is between the sun and Earth and in the Earth-sun plane. In the diagram, the moon is in the Earth-sun plane when it is passing from the part of its orbit indicated by the dashed line (i.e., below the plane) to the part of its orbit indicated by the solid line (i.e., above the plane). The moon is in this position and between the sun and Earth in position 3.