The cell is considered to be the most basic living unit.
An ectotherm gets its heat from external sources
(Remember "ecto" means outer, "endo" means inner)
Https://www.google.com/search?q=why+do+hot+air+balloons+rise&oq=why+do+hot+&aqs=chrome.1.69i57j0l5.3...
hope that helps
It's a reflex to protect your eye.