Answer:
Some common mental signs of eating disorders are low self-esteem of one's self, social withdrawal, fear of eating with other people, mood swings, anxiety, and many more red flags. Eating disorders are more mental disorders than digestive disorders because they severely impact a person's view of themselves.
Fingers, because people are usually messing with electricity and their fingers are by it.
DNA helps scientists to better classify organisms is because each organ has a specific kind of DNA. For an example, brains and hearts have many small types of RNA. So if a scientists see some RNA they know that its a heart or a brain.