
Concept explainers
Introduction:
RNA world theory states that amino acids and

Answer to Problem 1MCQ
Correct answer:
The statement that must be true for natural selection to occur in the RNA world is “Both b and c are correct”. Hence, the correct answer is option d.
Explanation of Solution
Reason for correct answer:
Option d. is given as, “Both b and c are correct.”
RNA is known to be the first non-dependent originator to life on Earth. It is believed that initially proteins were encoded by RNA. This led to the growth of RNA resulting in the production of enzyme reverse transcription. Reverse transcriptase is responsible for the conversion of RNA to DNA. Along with these encoding, it is highly possible that mutations took place during these processes.
Reason for incorrect answer:
Option a. is given as, “RNA molecules must turn into DNA molecules.”
It is not necessary for RNA molecules to convert it into DNA molecules. These molecules are important for copying DNA. Hence, option a. is incorrect.
Option b. is given as, “RNA molecules must undergo mutations.”
It is highly probable that RNA molecules underwent mutations but this cannot be the sole reason for the occurrence of natural selection in an RNA world. Hence, option b. is incorrect.
Option c. is given as, “RNA molecules must replicate.”
Replication is important for RNA to grow. For natural selection, replication plays a major role but is not the only factor responsible for the occurrence of natural selection. Hence, option c. is incorrect.
Hence, the options a., b., and c. are incorrect.
In order to undergo natural selection, RNA must show replication and undergo mutations. Thus, the correct option is d.
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Chapter 15 Solutions
Biology: The Essentials
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