Did you get it? If the sugar concentration in a cell is 4% and the concentration in the cell's
environment is 2%, how can the cell obtain more sugar?
A. Sugar can diffuse straight through the phospholipid bilayer.
B. Sugar can undergo facilitated diffusion through a channel protein and no
energy is required.
C. The cell CANNOT obtain any more sugar. It is doomed,
D. The cell must use active transport to pump the sugar in. Energy is
required.

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the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.