NES Profile: Middle Grades General Science (204)

The conclusion that Earth's outer core is liquid is based on which of the following evidence?

1. the characteristics of minerals retrieved from deep-ocean drilling
2. the changes in Earth's magnetic field recorded over the past century
3. the composition of igneous rocks from major volcanic eruptions
4. the behavior of seismic waves as they travel through Earth's interior

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D. This question requires the examinee to demonstrate knowledge of Earth's formation, history, and structure, as well as supporting geologic evidence. 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.

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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D. This question requires the examinee to identify the processes and characteristics of marine and freshwater systems, including oceans and glaciers. 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.

The polar front jet stream and the subtropical jet stream are located in which layer of the atmosphere?

1. the lower mesosphere
2. the tropopause
3. the upper stratosphere
4. the stratopause

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B. This question requires the examinee to demonstrate knowledge of the structure and characteristics of the different layers of the atmosphere. The polar front jet stream is at an elevation of approximately 7 km to 12 km above sea level. The subtropical jet stream is at an elevation of approximately 10 km to 16 km above sea level. Since the troposphere extends from Earth's surface to approximately 20 km above sea level, the polar front and subtropical jet streams are within the tropopause.

The diagram is not to scale. Earth is shown in four equidistant points on its orbital path, numbered counterclockwise, with position 1 at the top of the diagram. In each position, Earth's axis is shown tilted to the right, and the left half of the moon's orbit is shown with a dashed line. In position 1, the moon is shown on the far side of Earth from the sun, placing it at the point between the solid line and the dashed line portions of its orbit. In position 2, the moon is shown on the near side of Earth from the sun, placing it at the midpoint of the solid line portion of its orbit. In position 3, the moon is shown on the near side of Earth from the sun, placing it at the point between the solid line and the dashed line portions of its orbit. In position 4, the moon is shown on the far side of Earth from the sun, placing it at the midpoint of the solid line portion of its orbit.

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 those parts of the moon's orbit that are shown with a dashed line in the diagram above. 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

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C. This question requires the examinee to analyze the interactions of the sun, moon, and Earth and the effects of these interactions on Earth. 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 response that shows the moon in this position and between the sun and Earth is response C.