AP Environmental Science : Soil Formation, Composition, and Properties
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Example Questions
Example Question #1 : Soil Formation, Composition, And Properties
Which soil layer is composed of weathered rock (parent material) and contains little to no organic matter?
The B Horizon
The D Horizon
The C Horizon
The A Horizon
The O Horizon
The C Horizon
The O Horizon is composed of humus (organic matter), the A Horizon is a mixture of minerals and organic matter, the B Horizon is composed mainly of minerals and the D horizon is solid bedrock. The C Horizon best fits this definition, as it is the layer above the bedrock, consisting mostly of weathered rock fragments.
Example Question #1 : Soil Formation, Composition, And Properties
Which of the following choices best describes the process by which soil horizons accumulate material such as iron, clay, organic compounds, and aluminum?
Saturation
None of these
Innervation
Illuviation
Illuviation
Leaching occurs when percolating water transports materials from the top soil layers. Usually, these materials are illuviated (deposited) to a lower level.
Example Question #24 : Soil And Geology
Which element is not a component of soil?
Mineral material
None of these
Living organisms
Partially decomposed organic matter
None of these
All of these components make up soil. Differences in ratios of these components account for different soil types.
Example Question #25 : Soil And Geology
__________ is soil with the smallest particles. (Less than 0.002mm diameter).
Silt
Clay
Loam
Sand
Clay
Clay has the smallest particles, followed by silt, which contains larger particles than clay, but smaller particles than sand. Loam is a mixture of these three types of soil.
Example Question #26 : Soil And Geology
Soil is categorized by composition and depth. Each category is referred to as a __________.
horizon
level
cast
group
horizon
Soil categories are referred to as "horizons." Additionally, a vertical cross section of soil horizons is called a "profile."
Example Question #2 : Soil Formation, Composition, And Properties
Which type of rock is found deep below the Earth's surface and is formed by intense heat and pressure?
None of these types
Igneous
Sedimentary
Metamorphic
Metamorphic
Metamorphic rock is the only kind of rock that is formed below the Earth's crust. Igneous rock is formed by lava and volcanic activity. Sedimentary rock is formed by the collection of sand and other microscopic components that are fused together. Generally, the last two kinds of rock are found in the crust only, unless they are melted into lava.
Example Question #1 : Soil Formation, Composition, And Properties
The soil beneath your feet is stratified into layers that help us understand how soil is formed. If you collected a soil sample that contained accumulations of clay and subsoil, from which horizon (layer) did this soil come?
R Horizon
A Horizon
O Horizon
C Horizon
B Horizon
B Horizon
The correct response is B Horizon. The B horizon is referred to as the zone of accumulation because all the clay, minerals, and subsoil that is washed into it via illuviation from the overlying layers of soil. The B horizon is usually dark red or brownish due to the presence of clay and iron oxides.
Example Question #24 : Soil And Geology
Soil is stratified into different layers, called horizons. Which horizon contains freshly fallen leaves, plant litter, and lots of organic matter?
C Horizon
R Horizon
O Horizon
A Horizon
B Horizon
O Horizon
The correct response is O Horizon. This O horizon is the layer closest to the surface - typically between the depths of 0 to 2 inches, and contains freshly fallen leaves, plant litter, and lots of other organic matter.
Example Question #1 : Soil Formation, Composition, And Properties
What are soil horizons?
The chemical properties of the soil
The horizontal layers of soils
The result of human disturbances
The physical properties of the soil
The materials that make up the soil
The horizontal layers of soils
There are six types of soil horizons and each has different chemical or physical properties. Each type of soil has a different number of horizons. The horizons start at the parent material (bedrock) and continue up to the surface.
Example Question #1 : Soil Formation, Composition, And Properties
What is the brown insoluble particles from partially decomposed organic matter?
Minerals
Waterlog
Humus
Rill
Clay
Humus
The correct response is humus. This is one of the most important components to soil communities. Humus is formed as things like leaves, branches, and other vegetation breakdown (slowly) over time. Earthworms and microbes help speed up the process of breaking down dead organic matter into humus.
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