| 1. | Duplicate genes | 2. | Pseudo genes |
| 3. | Linked genes | 4. | Codominant genes |
| 1. | The two genes are closely linked on the same chromosome |
| 2. | The two genes are linked but on different chromosomes |
| 3. | Recombination did not occur in the cell during meiosis |
| 4. | The test cross was improperly performed |