What is the role of hydrogen bonds in structure of dna? ?

When does dna replication(make a copy of itself)?

In dna, only the_ varies from one nucleotide to another. base phosphate sugar amino acid

Which statement best explains why cells were observed in more detail using a compound microscope than a simple microscope? a compound microscope has greater magnification ability than a simple microscope. the compound microscope was invented before the simple microscope. a compound microscope is much easier to manufacture than a simple microscope. compound microscopes were more common than simple microscopes.