Homologous structures in organisms suggest that the organisms:
have a common ancestor
must have lived at different times
have a skeletal structure
are now extinct

Molecular models of two different substances are shown below. in the molecule on the left, the oxygen atom pulls on electrons more strongly than the hydrogen atoms. in the molecule on the right, the two oxygen atoms pull on the shared electrons with the same strength. water molecule, h,o oxygen molecule, oz when the two substances are put in the same container, they do not attract each other. why does this happen? a. they both contain oxygen. b. one is polar and one is nonpolar. c . they are both polar. d. they contain different elements.

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

Describe the two types of vascular tissue