7: symbiotic relationship
8: mutualism
9: commensalism
When your body temperature is too high your blood vessels will dilate then your sweat glands secrete fluid and the heat is lost from the body.. there for without sweat you would “heat to death”
If you're talking about eukaryotic cells then it's the cell wall. If it's a prokaryotic cell sometimes the slime layer secreted by some bacteria may harden and form a capsule around the bacterial cell.
Hope i helped!