Name the Biologist - Week 12

This week i'm doing a few mug shots as they are all connected. You can guess the connection and if you're really smart name them too. So here we go

A) this guy had the hypothesis;

B) And these two helped prove it by finding a key component;

As for last week's answer it was no other than Hans Adolf Krebs of "the Krebs Cycle" fame. I told you he was someone most high school Biology students will have encountered or cursed at some point in their lives. Although once memorised, that was a gift of an exam question.