During the process of gene amplification using PCR, if very high temperature is not maintained in the beginning, then which of the following steps of PCR will be affected first ?

The correct step of PCR that will be affected first if a very high temperature is not maintained in the beginning is Denaturation.

Understanding the Steps of PCR (Polymerase Chain Reaction):
PCR is a laboratory technique used to amplify a specific segment of DNA. It involves a cycle of three main temperature-dependent steps:

1. Denaturation (typically 94 - 96 °C): This is the first step of the PCR cycle. In this step, the double-stranded DNA template is heated to a high temperature. The heat breaks the hydrogen bonds holding the complementary bases together, separating the double-stranded DNA into two single strands. If this very high temperature is not maintained in the beginning, the hydrogen bonds cannot be broken, and the DNA strands will not separate. Thus, this step is affected first and fails to occur.
2. Annealing (typically 50 - 65 °C): In this second step, the temperature is lowered to allow DNA primers to bind (anneal) to their complementary sequences on the single-stranded DNA templates.
3. Extension (typically 72 °C): In the third step, the temperature is slightly raised to the optimum temperature for the DNA polymerase enzyme (usually Taq polymerase) to synthesize a new DNA strand complementary to the template strand by adding nucleotides.

Conclusion:
Since Denaturation is the very first step in the cycle and requires a high temperature to break the hydrogen bonds between double-stranded DNA, it is the step that will be affected first if high temperature is not maintained.