Most of the mass of an atom is concentrated in the

Provide one reason why mitosis occurs.

I’m doing some practice exam questions for biology, and i’m not sure how to do these 3 parts to the question.

In a cross between individuals of a species of tropical fish, all of the male offspring have long tail fins, and none of the females possess the trait. mating two of the f1 fish fails to produce females with the trait. explain the inheritance pattern of the trait.