What are the four parts of darwin's theory of evolution? i think it is adaptation, variation, over-reproduction, and natural selection. am i correct?

All individuals have two alleles for a given trait. according to mendel's these alleles are passed down one each from both mother and father.

There are few cells in the body that do not undergo mitosis: most somatic cells divide regularly, some more than others. take for example the cells that line the digestive tract. these cells must be frequently replaced because they are constantly eroded by the movement of food through the tract. what mechanism(s) is/are in place to ensure that these cells are exact copies of the mother cell

Strands of genetic material floating in the nucleus are referred to as