Question

which statement best describes how watson and cricks model used other scientists work to create a model of dna?
they used chargaffs rule to determine that it contains ribose sugar.
they used franklins photo to determine that dna was a double helix.
they used levenes work to determine the number of base pairs in each strand.
they used nirenberg and mattheis studies to determine that dna is made of nucleotides.

Explanation:

• Analyze Option 1: Chargaff's rule is about base pairing (A=T, G=C), not ribose sugar (DNA has deoxyribose, RNA has ribose). So this is incorrect.
• Analyze Option 2: Rosalind Franklin's X - ray diffraction photo (Photo 51) provided crucial evidence about the double - helix structure of DNA, which Watson and Crick used to develop their model. This is correct.
• Analyze Option 3: Levene's work was on the structure of nucleotides (identifying sugar, phosphate, base), not on the number of base pairs in each strand. So this is incorrect.
• Analyze Option 4: Nirenberg and Matthei's work was on deciphering the genetic code (relating mRNA codons to amino acids), not on determining that DNA is made of nucleotides. So this is incorrect.

Answer:

B. They used Franklin’s photo to determine that DNA was a double helix.