| A | B |
|---|
| heredity | the passing down of traits from parents to offspring |
| chromosome | threadlike structure in a cell nucleus that holds thousands of bits of information about an organism's traits |
| gene | a bit of information in a chromosome |
| fertilization | the joining of a sperm cell and an egg cell |
| mutation | a change in the genetic code of an organism |
| body cell | The nucleus of every __________ in humans contains 23 pairs of chromosomes. |
| dominant | In pea plants, the trait for roundness is __________ over the trait for wrinkling in seeds. |
| selective breeding | Farmers use _______ to control the traits of their plants and animals. |
| DNA | A cell nucleus contains chromosomes that are made of __________. |
| sex cell | In humans, every ____________ has 23 chromosomes. |
