Q1: In the study of one experiment it was found that the value of Tm for DNA is = 40° C. If the cell has 20% GC at the above Tm, then what will be value of 'Tm' if the GC% increases to 60%?

ANS:B - Increases

The %GC cannot really increase for a given species, and "the cell has 2'% at the above Tm" is not a good wording.

It would be better to present as 2 species, one with 20% GC and the other with 60% GC, and compare the Tm of DNA from each species.