Answer:Although protons resemble other positive ions such as Na+ and K+ in their movement across membranes, in some respects they are unique. Hydrogen atoms are by far the most abundant type of atom in living organisms; they are plentiful not only in all carbon-containing biological molecules, but also in the water molecules that surround them. The protons in water are highly mobile, flickering through the hydrogen-bonded network of water molecules by rapidly
D, because both A and C are correct.
False- because there are other marine habitats such as lakes, ponds, etc.
The heart needs molecule don’t take me serious cause it might be wrong
I think it's the simple columnar epithelium.
