6. Which classification system is based on appearance rather than genes?
- Artificial
- Natural
7. Which classification system is based on organisms' evolutionary relationships and genetic similarities?
- Natural
- Artificial
8. Which of these is NOT a problem with identifying species?
- Hybrids
- Evolution
- Sexual reproduction
- Asexual reproduction
9. A group of organisms that interbreed to produce fertile offspring is called a...
- Species
- Order
- Genus
- Family
