What are some differences between eukaryotic and prokaryotic cells?
Eukaryotic cells have a nucleus, membrane-bound organelles, DNA, and are usually multicellular. Prokaryotic cells do not have these qualities.
Does atomic size increase or decrease going across the periodic table?
Atomic size decreases going across the periodic table because atoms become more positively charged, which causes electrons to be more tightly held and the atomic radius to decrease in size.
How does the structure of a phospholipid contribute to the impermeability of the lipid bilayer of cell membranes?
Phospholipids have a polar, hydrophilic head and nonpolar, hydrophobic tail. In the bilayer, the heads face the aqueous portions of the cell, and the tails face inwards, towards each other. Such an organization makes the lipid bilayer of cell membranes highly impermeable to large molecules and small polar molecules.