Across
- 3. Air sacs in lungs where gas exchange takes place.
- 4. The fluid within a cell that holds organelles and performs metabolic reactions.
- 7. Plant cells have this to give its rigid structure.
- 9. The physical breakdown of food.
Down
- 1. The control centre of the cell.
- 2. This organelle performs photosynthesis.
- 5. This organ filters waste and excess fluid from blood,which is then excreted as urine.
- 6. The human heart has four of these.
- 8. Structure in the heart that ct like one-way doors to prevent backflow of blood.