The Question is from neet-botany molecular-basis-of-inheritance , and it was created by the author K SURESH KUMAR

Question

If the RNA world hypothesis is correct, which of the following would be the MOST likely scenario for the emergence of DNA?

K SURESH KUMAR · Accepted Answer

## CORE INFORMATION
✓ **Answer**: C
## CONCEPT FRAMEWORK
 **Primary Concept**: RNA world hypothesis and the evolution of DNA
 **Related Topics**: Origin of life, molecular evolution, nucleic acid biochemistry
 **Prerequisites**: Understanding of RNA and DNA structure and function, basic principles of evolution.
## SOLUTION PATHWAY
**Given Information**:
The RNA world hypothesis posits that RNA, not DNA, was the primary genetic material early in life's history.
**Method & Steps**:
1. Consider the RNA world hypothesis: RNA molecules possess both catalytic and informational properties.  This makes them plausible candidates for early life forms.
  Reasoning: If RNA was the primary genetic material, the transition to DNA would likely involve RNA playing a central role.
  Formula/Rule: None directly applicable.
2. Evaluate each option in light of the RNA world hypothesis:
  Working:
  A. This option contradicts the RNA world hypothesis by suggesting independent DNA origin.
  B. This option suggests proteins evolved *before* DNA and RNA, which is inconsistent with the RNA world hypothesis.
  C. This option aligns well with the RNA world hypothesis: RNA, already established, develops the ability to create the building blocks of DNA and then polymerize them into DNA. This is a plausible evolutionary pathway.
  D. This option is highly improbable and lacks scientific evidence.
 3. Determine the most likely scenario:
  Result: Option C is the most likely scenario given the RNA world hypothesis.
  Verification: Option C provides a plausible evolutionary pathway from an RNA-based system to a DNA-based system, with RNA playing a crucial role in the transition.
 ## OPTION ANALYSIS
A :x:  This is unlikely; the RNA world hypothesis suggests RNA came first.  Independent DNA origin would require a separate, and less likely, evolutionary pathway.
B :x: The RNA world hypothesis states that RNA preceded proteins, so proteins catalyzing DNA formation from RNA is inconsistent.
C ✓: This option is the most plausible. RNA having the capacity to synthesize deoxyribonucleotides and polymerize them directly explains the transition to DNA within the context of the RNA world.
D :x: This option is highly speculative and lacks supporting evidence. The introduction of extraterrestrial DNA is not a well-supported hypothesis for the origin of life on Earth.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Assuming DNA arose independently of RNA:  The RNA world hypothesis strongly suggests a connection between RNA and DNA's origin.
  2.Ignoring RNA's catalytic properties: RNA's ability to catalyze reactions is crucial to its role in the RNA world and the transition to DNA.
 **Quick Tips**:
  1.Remember the central tenets of the RNA world hypothesis: RNA as the primary genetic material and its catalytic capabilities.
  2.Focus on evolutionary plausibility:  Which scenario offers the most logical and stepwise progression from an RNA-based world to a DNA-based world?

K SURESH KUMAR · Answer

DNA spontaneously arose independent of RNA and eventually outcompeted RNA.

K SURESH KUMAR · Answer

Proteins evolved first and then catalyzed the formation of DNA from RNA.

K SURESH KUMAR · Answer

The correct Option is "RNA developed the ability to synthesize deoxyribonucleotides and polymerize them, eventually leading to DNA genomes."

K SURESH KUMAR · Answer

Extraterrestrial DNA was introduced to Earth and replaced RNA.

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