Explain how the discoveries by Rosalind Franklin helped Watson and Crick build an accurate model of DNA.

Answer:

Rosalind Franklin's X-ray diffraction image (Photo 51) provided evidence that DNA is shaped like a double helix. Her work showed that the sugar-phosphate backbone was on the outside and the nitrogenous bases were on the inside. She also provided precise measurements, such as the diameter of the helix and distance between bases, which Watson and Crick used to construct their accurate 3D model.