Evidence indicates that 251 million years ago a mass extinction of many life-forms occurred on earth. which form of life became extinct at this time?

The answer is trilobites. They are among the life forms that became extinct 250 million years after a calamity in the  Permian-Triassic extinction event. It is presumed that nearly 95% of world species were wiped from the face of the earth and this gave rise to the reign of the dinosaurs (that also became extinct 65 million years ago due to asteroid strike). The cause of this major extinction event is yet to be established.

i do not know and i have a 100 in this class

protocol for imps extraction focusing on membrane protein extraction, solubilisation, and purification.