| A | B |
|---|
| mitosis | the process by which a cell produces two new identical nuclei |
| cell division | the dividing of a cell following mitosis |
| asexual reproduction | reproduction by one parent |
| sexual reproduction | reproduction by two parents |
| sex cell | a type of cell produced only by an organism that reproduces sexually |
| meiosis | the process by which sex cells form |
| fertilization | the joining of an egg cell and a sperm cell during sexual reproduction |
| zygote | the first cell of an offspring, formed when an egg cell and a sperm cell join |
| trait | a characteristic of an organism |
| DNA | the molecule in each cell that directs the cell's activities |
| gene | a section of DNA on a chromosome that controls a trait |
| base | one kind of molecule that makes up a DNA strand |
| heredity | the process by which traits are passed from parents to offspring |
| inherit | to receive from one's mother or father |
| dominant gene | a gene that prevents the expression of another gene |
| recessive gene | a gene whose expression is prevented by a dominant gene |
| purebred | an organism with two dominant or two recessive genes for a trait |
| hybrid | an organism with one dominant and one recessive gene for a trait |
| mutation | a permanent change in DNA that occurs when DNA copies itself |
