A fossil is the preserved remains of a dead organism from millions of years ago. Fossils of the simplest organisms are found in the oldest rocks, and fossils of more complex organisms in the newest rocks.
This supports Darwin's theory of evolution, which states that simple life forms gradually evolved into more complex ones. Evidence for early forms of life comes from fossils.
Cells are the basic building blocks of all living things. All living things are made up of cells. Cells have many parts, each with a different function.
The nucleus of a cell contains chromosomes, which are made up of DNA.
DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. DNA carries the characteristics that we inherit.
Genes carry the information that determines the traits which are features or characteristics that are inherited from parents.