Chapter 23, Problem 1A

Summary Introduction

Introduction:

Stanley miller performed an experiment to prove that organic molecules were produced by the inorganic molecules present in the primitive earth. He created a condition exactly like that of primitive earth to show the origin of life. He used molecules that were believed to be present in the atmosphere of the primitive earth and passed an electric current through it. This resulted in the formation of organic molecules like amino acid.

Answer to Problem 1A

Correct answer:

Stanley Miller used a solution of methane, ammonia, and hydrogen gases and passed an electric current through it. This resulted in the formation of organic molecules. Therefore, option (c) is correct.

Explanation of Solution

Reason for the correct statement:

Stanley Miller used gases that were believed to be present in the atmosphere of the primitive earth, like hydrogen, methane, and ammonia in a closed system in the absence of oxygen. Then an electric current was passed that resulted in the formation of organic molecules.

Option (c) is given as “gases found in the atmosphere of early earth”.

As, “Stanley Miller used the gases that were found in the atmosphere of early earth to prove his hypothesis.” So, option c is the right answer.

Hence, option (c) is correct.

Reasons for the incorrect statements:

Option (a) is given as “microspheres”.

Stanley did not use the microspheres in his experiments as these are the organic molecules that were not present in the primitive earth. So, it a wrong answer.

Option (b) is given as “purines and pyrimidines”.

Stanley did not use these as they were the organic molecules that were formed after the completion of the experiment. They were absent in the primitive earth and were formed later from the inorganic molecules. So, it is an incorrect answer.

Option (d) is given as “only RNA”.

RNA was not present in the primitive earth as they were formed later. Stanley did not use them for this reason only. So, it is an incorrect answer.

Option (e) is given as “All of these are correct”.

Stanley used only the gases found in the primitive earth and did not use the microspheres, purines, pyrimidines and RNA to prove his hypothesis. So, it is an incorrect answer.

Hence, options (a), (b), (d) and (e) are incorrect.

Conclusion

Stanley Miller used gases found in the primitive earth to show the evolution of organic molecules like amino acids, proteins from the inorganic ones in the absence of oxygen during the origin of life.