How many veins and arteries are present between the maternal and the fetal circulatory system by the fifth week of pregnancy?

The development of_ factored in the development of complex organisms.

Prokaryotic and eukaryotic cells are different in many ways other than the presence or absence of a nucleus. if both archaebacteria and eubacteria are prokaryotic cells, then why are archaebacteria more closely related to eukaryotic cells than they are to eubacteria?

In what locations does this text suggest you might find zooflagellates living? fresh water lakes on the surface of leaves inside other organisms on damp forest floors