There is not that much wheat in the entire world.

Yes, that's right!

It would take:

1 + 21 + 22 ... + 263

= 18,446,744,073,709,600,000

= 1.8 x 1019 grains of wheat

to fill the entire chessboard. If 1 grain of wheat weighs 1 gram, that's 1.8x1013 tons - more than the entire wheat harvest of the world!

Similarly, in a 30 cycle PCR reaction starting with just one copy of the template DNA, you could POTENTIALLY make:

1 + 21 + 22 ... + 229 = 1,061,109,567 copies of the starting DNA.

In reality, the reaction is not 100% efficient, so considerably less than this is produced. Even so, PCR is an immensely sensitive technique.

What alternative methods could be used to show that HPV infection plays a role in cervical carcinoma?

Serology:
YES NO

Symptoms (warts):
YES NO

Electron microscopy:
YES NO

Virus culture:
YES NO

Immunofluorescence:
YES NO

In situ hybridization:
YES NO

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