What part did you need help understanding? Your definition is pretty strong- the epiglottis keeps food from entering the trachea and lungs. It also opens during breathing to allow air into the lungs. Good luck on your test, let me know if you need anymore refreshers!
Layers of fossils in pillars, the rock covering them is dated and we get an exact time of each layer.
Is about 3 hours to my understanding
Centromere
Meaning the most condensed and constructed region
