AP Environmental Science Unit 4 Practice Test: Earth Systems & Resources

The correct answer is (B). Beneath the ocean floor, tectonic plates move away from each other at the divergent plate boundary. A subduction zone is where the tectonic plates pass over one another. Seafloor spreading does not describe the movement of the plates; instead, it describes the mantle pushing upward through to the surface. At a convergent plate boundary, the tectonic plates move toward one another, and at a transform fault boundary, the plates move past each other. The tectonic plates move away from each other due to the force of magma rising through and splitting the lithosphere, of which the tectonic plates are made.

The correct answer is (B). The inner and outer core of the earth both consist of iron and nickel. Although the inner core is hot, its accompanying 330–360 gigapascal pressure keeps it in the solid phase. The outer core, although hot, lacks the pressure to keep it in the solid phase; consequently, it is the only layer of Earth in the liquid phase. The mantle is made up of magma, which is molten rock, and not considered liquid. The asthenosphere is semi-molten, but not liquid. The lithosphere is composed of both the earth’s crust and the outer mantle, both of which are solid.

The correct answer is (B). Soil degradation describes the loss of some or all of a soil’s ability to support plant growth resulting from biological, chemical, or physical deterioration. Weathering describes the breakdown of rocks and minerals, not soil. Erosion describes the process by which rock fragments and soils are removed from a landscape, but does not specifically describe a soil’s capacity for supporting plant growth. Base saturation describes the proportion of soil bases to soil acids, and does not specifically relate to soil supported plant growth.

The correct answer is (B). As soil ages, the amount of organic material in it increases proportionally. Immature soil develops into young soil as plants and organisms die. Eventually, young soil becomes mature soil, which contains all of organic material present in each of the earlier stages.

The correct answer is (B). The troposphere is the lowest portion of the atmosphere and ranges in depth from about 8 km – 14.5 km. The stratosphere is the second layer of the atmosphere and contains the ozone layer. The third layer, the mesosphere, is where most meteors burn up when entering the atmosphere. The thermosphere is the fourth layer and is where the International Space Station orbits.

The correct answer is (A). The innermost layer of the earth is the solid inner core, followed by the liquid outer core, then the mantle and finally the crust.

The correct answer is (D). Transform plate boundaries occur when plates move sideways past each other.

The correct answer is (C). The B horizon consists mostly of minerals and very little organic matter.

The correct answer is (A). A soil’s texture is determined by the percentages of sand, silt and clay contained in the soil.

The correct answer is (D). No more than 3% of Earth’s water is fresh water. Fresh water sources are approximately distributed as follows:

0.04% Atmospheric water
0.3% Surface water
30% Ground water
68+% Ice and glaciers

The correct answer is (B). The following lists the atmospheric layer from the closest to the Earth increasing in altitude:

Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere

The correct answer is (D). Amending the soil with sand would increase the porosity of the soil allowing water to drain better and decreasing the chance of crops drowning. Clay would cause the water to sit on the surface even longer due to decreased porosity. Contour plowing would likewise help the water to sit in place longer. Increased organic material in soil also increases water-holding capacity.

The correct answer is (C). To read the above chart you start with the percent sand and find the intersecting line with clay and then silt.

The correct answer is (A). Most weather occurs in the Troposphere where water evaporating from the surface of the Earth rises with warm air and as the air cools the water condenses and falls back to the surface as precipitation.

The correct answer is (D). 78% of our atmosphere is Nitrogen. Oxygen makes up 21% and the rest of the gases account for around 1% by volume.

The correct answer is (C). Clay has the lowest porosity of the three components of soil and prevents drainage. Sandy loam has higher amounts of sand and silt allowing good drainage while still holding enough water for the soybeans.

The correct answer is (A). The tilt of the Earth’s axis is what drives the Earth’s seasons as the hemisphere tilted towards the sun receives more solar energy than the hemisphere tilted away from the sun.

The correct answer is (A). Crop rotation helps to reduce soil erosion. Increased soil erosion leads to more sediment in local waterways. Removing vegetation around the fields would also increase soil erosion as would turning them into cattle pasture. Use of synthetic fertilizers can lead to eutrophication in local waterways if excess N and P runoff from the fields makes its way into them.

The correct answer is (B). Warm water currents flow up and around Iceland as part of thermohaline circulation. Cold arctic currents then flow down and around Greenland having the opposite effect on it. Both countries receive similar amounts and intensities of solar radiation.

Sediment carried downstream by rivers bring needed nutrients to the ecosystems found there.