Which of the following statements about PCR phases is accurate?

The statement that standard PCR measures during the exponential phase is accurate because, during this phase, the quantity of the target DNA is doubling with each cycle, allowing for a clear and measurable increase in DNA amplification. This ensures that the reactions can be effectively quantified, as the amount of product formed is directly proportional to the initial amount of template DNA. This exponential growth phase occurs during the optimal cycles of PCR when the enzyme is actively synthesizing new DNA.

In contrast, qPCR (quantitative PCR) continuously monitors the amplification of DNA in real-time, typically during the exponential phase as well, to gather quantitative data rather than relying on end-point analysis. As such, saying qPCR measures during the stationary phase is misleading because stationary indicates a plateau where DNA amplification no longer rises. Additionally, both standard PCR and qPCR provide results after the run is complete; however, qPCR provides more immediate and quantitative insights throughout the run rather than only upon completion, which is relevant for temporal analysis.