Final answer:
A fluorometer is necessary to measure and quantify the DNA produced during real-time PCR by monitoring the fluorescence emitted by a dye that intercalates with the double-stranded DNA.
Step-by-step explanation:
To quantify the DNA produced during real-time PCR, also known as quantitative PCR or qPCR, the type of apparatus needed is a fluorometer. A fluorometer is equipped to monitor the fluorescence emitted by a fluorescent dye that gets incorporated into the DNA as it is being synthesized during the PCR reaction. This fluorescence is directly proportional to the amount of double-stranded DNA produced in the reaction. Therefore, by measuring this fluorescence in real-time, one can quantify the DNA produced.