Question

Scientists build models based on what they know from previous research to derive testable hypotheses.Independently, both Watson and Crick and their competitor Linus Pauling constructed an incorrect triple-helix model with the nitrogenous bases arranged so they were on the exterior of the molecule and the phosphate groups on the interior. What evidence caused Watson and Crick to revise their model (CHOOSE 2)

Answer 1

Hello. You didn't show the answer options, but we can consider that Watson and Crick revised the DNA model after seeing DNA images taken through Franklin's x-ray and by observing the pairing of the nitrogenous bases.

Step-by-step explanation:

For a long time it was believed that the DNA molecule had 3 strands, instead of two, however this information was inaccurate and although defended by some scholars it was somewhat controversial and showed the need for further investigation. With that in mind, Watson and Crick decided that it was necessary to evaluate DNA in a three-dimensional way and therefore, they obtained x-ray images of DNA molecules, taken by Franklin. In these images, it was possible to notice that the DNA had two strands, instead of three. To prove this discovery, Watson and Crick analyzed the nitrogenous bases discovered by Chargaff and the way they were paired, coming to the conclusion that the DNA had two strands.