Answer:
a) The annealing temperature may be defined as the temperature required to join or anneal the DNA strands. If the annealing temperature will be too high the primers may denature in the PCR reaction and no amplification of DNA will occur.
b) The annealing temperature is too low, the primers are unable to bind with the DNA and no reaction of PCR will occur. Too low annealing temperature will not favor the primers to bind and amplify the DNA.