| A | B |
|---|
| Respire | Take in oxygen and give off carbon dioxide. |
| Diffusion | The movement of materials from an area of high concentration to an area of low concentration. |
| Circulatory | Flowing in a circle |
| Open circulatory system | A system in which blood makes direct contact with cells. |
| Annelid | A segmented worm or a worm whose body is divided into sections. |
| Closed circulatory system | A system in which blood stays inside vessels at all times. |
| Atrium | A heart chamber that recives blood returning to the heart. |
| Ventricle | A heart chamber that pumps blood out of the heart. |
| Excrete | Get rid of wastes or substances that are not needed. |
| Flame cell | A cell that collects excess water in a flatworm. |
| Kidney | An organ of excretion found in vertebrates. |
