WJEC Biology Unit 1
Biology
aaaaaaaaaaaaaaa
Sample Data
| Front | What is the tunica externa? |
| Back | The outer layer which contains collagen fibres, which resist overstretching. |
| Front | Xylem has two functions: |
| Back | 1. Transport of water and dissolved minerals.2. Providing mechanical strength and support. |
| Front | What is the submucosa?
 |
| Back | The submucosa is connective tissue containing blood and lymph vessels, which remove absorbed products of digestion, and nerves that co-ordinate peristalsis. |