Which pair of statements best describes an essential amino acid?
a. it is an amino acid that contains peptide bonds. an example is proline.
b. it is an amino acid that contains nitrogen. an example is aspartic acid.
c. it is an amino acid that cannot be made by the body. it must be obtained from eating certain foods.
d. it is an amino acid that can be produced by the body. vitamin supplements maintain healthy levels.

because they are eaten by the frog and the frog getseaten by the snake and the snake by the eagle

water is a polar molecule. a chemical bond is a force of attraction between atoms or ions. bonds form when atoms share or transfer valence electrons. atoms form chemical bonds to achieve a full outer energy level, which is the most stable arrangement of electrons. so, false

explanation:

in h2o molecule, two water molecules are bonded by a hydrogen bond but the bond between two h - o bonds within a water molecule are covalent. the greater the electronegativity difference, the more ionic the bond is. bonds that are partly ionic are called polar covalent bonds. nonpolar covalent bonds, with equal sharing of the bond electrons, arise when the electronegativities of the two atoms are equal.