Scientists in a particular field strive for the same quality of work because they know their peers will be reviewing their scientific claims. what does this review process ensure?

The review process mentioned is called peer review and it is when the scientists work and research is put to the scrutiny of other experts in the same field of research to check its validity (making sure it's claims are correct or justified) and evaluate whether is is a suitable piece of work for publication.  So it's for validity of the work and whether it can be published.

identify the dna change shown in the diagram and explain how that change can result in the increased genetic diversity often seen among siblings.

the answer is b.) hydrogen bonds between bases.