The fossil record shows at least five major mass extinctions have occurred since the beginning of life on earth. All of the above are true. The atomic mass of carbon is 12, the atomic mass of hydrogen is 1, and the atomic mass of oxygen is 16. Compared to vegetable oil, animal fat contains a higher proportion of fatty acids with saturated carbons, i.e. carbons with two hydrogen atoms. DNA and RNA 20.
Gap junctions allow the direct transmission of ions and sugars between connected mammalian cells.
Your pancreas contains cells which secrete large amounts of peptide hormones, i.e., polypeptides consisting of short chains of amino acid chains. In osmosis, water moves from a region of higher solute concentration to one with lower solute concentration through a semi-permeable membrane. With the unaided eye, we can resolve to approximately 0.2 mm. The electron microscope can resolve to 2 nm. For plants, cellular respiration occurs in the chloroplasts.