Pls help, I was absent and don't know it, they wouldn't let me sit out

Fossils can only be formed when? if mud, silt or tar is in the area to preserve the fossil ierosion does not occur and allows the fossil to form oxygen and microorganisms cannot decay the bones the area is dry and does not contain mud or silt

How does the study of genetic disorders such as pku biologists understand normal alleles?

Look at the photo of the leaf. which term best describes this leaf?