Use the drop-down menus to match each phrase below with the type of microscope it describes.
magnifies objects in steps
is the type that was used to observe the first strands of dna
contains a series of lenses
includes magnifying glasses
creates a digital image
uses one lens for magnification

the sugar-phosphate backbone forms the structural framework of nucleic acids, including dna and rna. this backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.

the solute can move "downhill," from regions of higher to lower concentration, relying on the specificity of the protein carrier to pass through the membrane. this process is called passive transport or facilitated diffusion, and does not require energy.