Carbon has different isotopes. what is different between an atom of 12c and an atom of 13c?
a. number of protons in the nucleus
b. number of neutrons in the nucleus
c. number of electrons in the atom
d. number of protons and electrons in the atom

What will most likely happen in the absence of a cell membrane? a) photosynthesis will not take place. b) the cell will not store food, water, nutrients, and waste. c) energy will not be released during cellular respiration. d) substances will pass in and out of the cell in an uncontrolled manner.