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Which of the following is NOT found in topsoil?
a. Humus
b. Bedrock
c. Bacteria
d. Air
Introduction:
The soil is an important part of the Earth. The soil layer of the Earth is called the pedosphere, which plays a vital role in Earth’s atmosphere. It provides medium for plant growth, water storage, and provides space for organisms to live. The soil composed of 50% solids that has minerals and organic matter, and other 50% pores are filled with water and gas.
Answer to Problem 1U
Correct answer:
The soil consists of humus, microorganisms including bacteria, and the pore space between the soil particles have air, however, the topsoil lack bedrock. Therefore, option b. is correct.
Explanation of Solution
Reason for the correct statement:
The soil is formed by the weathering of rocks and is the outermost layer of the crust of the Earth. It is comprised of rocks, sand, silt, clay, humus, and other organic matter. There are different layers of soil. The topsoil is the topmost layer of the soil. The topsoil is comprised of mineral particles, microorganisms, humus, sand, clay, silt, air, and water.
Option b. is given as "bedrock".
As “the bedrock is the innermost layer of the soil and is NOT found in the topsoil”, it is the right answer.
Hence, option b. is correct.
Reasons for the incorrect statements:
Option a. is given as “humus”.
The humus can be defined as the partially digested and decomposed organic matter. It is found in the topsoil. Therefore, it is a wrong answer.
Option c. is given as “bacteria”.
The topsoil consists of living organisms including bacteria, fungi, and other microorganisms. Therefore, it is a wrong answer.
Option d. is given as “air”.
The air in the topsoil is present in the pore space present between the particles of the soil. Therefore, it is a wrong answer.
Hence, options a., c., and d. are incorrect.
Conclusion:
The soil is formed by the weathering of rocks. It has several layers, the topmost of it is known as the topsoil. The topsoil is comprised of sand, silt, clay, air, humus, microorganisms and roots of the plants.
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Chapter 38 Solutions
GENERAL BIOLOGY I >CUSTOM<
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