True or False? All mutations have a negative effect on a population of organisms.

False, I believe. Mutations sometimes might have an effect that helps the population. Example: I've heard of Two-Headed snakes, and even seen some on the internet. They live their lives just fine, so I suppose the mutation was actually quite helpful.

evidence and logical support is essential for a scientist to do in order to maintain credibility. this is because no one can believe without any logic and without any evidence.hence a scientist can maintain credibility by proving himself and by answering logically so experiments prove very beneficial. logical hypothesis give conclusion which is acceptable. therefore, there are two main factors to maintain credibility by a scientist is evidence and logical support.