Index fossils assist paleontologists in dating rocks because they represent species that ?

Drag each label to the correct location on the image. each label can be used more than once. a scientist introduced mutations in a gene sequence isolated from bacteria. study the sequence, and identify the steps where the mutations may affect the formation of proteins. in the sequence, black letters stand for protein coding regions and red letters stand for noncoding regions. protein will not be changed. protein may be changed. attcgtgttc atcgtgttc atcgtattc attcgtattc

Is there any species that went extinct in recent years due to natural causes (not caused by human interaction). if so, what caused it?

How can you tell the difference between rough er from smooth er?