Final answer:
The most electronegative atoms in biological molecules are oxygen and nitrogen, which are responsible for creating partial negative charges on these atoms due to their ability to attract electrons more strongly than other atoms like carbon and hydrogen.
Step-by-step explanation:
The most electronegative atoms typically present in biological molecules are oxygen and nitrogen. These atoms are known for their ability to attract electrons within a chemical bond more strongly than other elements typically found in biological molecules, like carbon and hydrogen. Oxygen, with an electronegativity of 3.44, is particularly notable in this regard, as it tends to be the atom that electrons are most attracted towards, as seen in water (H2O), where oxygen carries a partial negative charge due to its high electronegativity.
Nitrogen also has a relatively high electronegativity (3.04) compared to other biological elements, which means that, similar to oxygen, it often carries a partial negative charge in molecules, as electrons will be more attracted to nitrogen atoms within a molecule, compared to carbon or hydrogen atoms.