6. Which of the following is in the order of increasing levels of complexity?
- Tissues-cells-organs-organ systems
- Organelles-cells-tissues-organs-organ systems
- Cells-molecules-tissues-body-organ
- Organelles-tissues-cells-organ systems-organs
7. Which organ system does the trachea belong to?
- Nervous
- Respiratory
- Digestive
- Circulatory
8. Two or more different tissues form a(n):
- Tissue
- Organ system
- Organ
- Cell
