1. why must dna have thymine instead of uracil? 2. why is it necessary for rna to have uracil instead of thymine?

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

The mammal pictured below is a silvery mole rat. which statement is an inference based on the picture? the animal is ugly. the animal has hairless feet with sharp claws. the animal has prominent upper and lower incisor teeth. the animal likely has poor vision since its eyes are so small.

Which of the following is the earliest era of earth's geologic time scale? cenozoic mesozoic precambrian paleozoic