Crossword Puzzle

2. – The smallest blood vessels where oxygen and nutrients are exchanged with tissues.
6. – The movement of molecules from an area of higher concentration to lower concentration.
8. – A muscular organ that pumps blood through the circulatory system.
9. – The movement of blood through the heart and blood vessels.
12. – Tiny air sacs in the lungs where gas exchange occurs.
13. – A muscle that helps with breathing by expanding and contracting the lungs.
15. – A fluid in the circulatory system that carries oxygen and nutrients to cells.

1. – A blood vessel that carries oxygen-rich blood away from the heart.
3. – The primary organ of the respiratory system in humans and many animals, responsible for gas exchange.
4. – Respiratory organs in fish and some amphibians that extract oxygen from water.
5. – A blood vessel that carries blood towards the heart.
7. – Tiny openings on plant leaves that allow gas exchange.
10. – Plant tissue that transports water from the roots to the rest of the plant.
11. – In some animals like earthworms, an organ used for gas exchange.
14. – Plant tissue that transports sugars and nutrients.