Meselsohn and Stahl investigated DNA in bacteria. They grew bacteria in a medium with only heavy nitrogen, ${}^{15}N$, until all of the bacterial DNA was heavy.
These bacteria were moved from a heavy nitrogen medium and cultured in a medium with only light nitrogen, ${}^{14}N$.
A sample of bacteria was collected from the first generation in the medium containing light
nitrogen and their DNA was analysed.
Hybrid DNA contains both heavy and light DNA.
Which row shows the percentage of heavy DNA strands and the percentage of hybrid DNA molecules in the first generation produced in the medium containing light nitrogen?
1 )
A
2 )
B
C
4 )
D
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