Final answer:
If a thermocycler used during PCR cannot heat up above 80 degrees, it may affect the denaturation, annealing, and extension steps of the PCR reaction.
Step-by-step explanation:
If a thermocycler used during PCR cannot heat up above a temperature of 80 degrees, it would have several effects on the PCR reaction. First, the denaturation step, where the double-stranded DNA template is separated into single strands, may not occur effectively at a lower temperature. Second, the annealing step, where the primers bind to the template strands, may not be efficient at a lower temperature. Finally, the extension step, where the DNA polymerase adds nucleotides to the primers to create new DNA strands, may be compromised at a lower temperature.