The external cell membrane. Even organisms as simple as bacteria have a cell membrane.
Prokaryotes do not have internal membranes but they still have external membranes.
Everything living thing has a cell membrane
A virus can be inside a body without showing up
I am going to assume it mean what i think it does and say <span>A) Predation</span>
Answer:
C) Primary, tertiary and quaternary levels of protein structure
Explanation:
Primary structure; Covalent bond is present in form of peptide bond in the primary structuture of proteins. The amino acids are held together in the polypeptide chain by peptide bond.
Tertiary structure; Disulfide bonds are present between cysteine amino acids, that keeps the parts of polypeptide chain strongly attached to one another.
Quaternary structure; The Quaternary structure of protein is held together by hydrophobic interaction and disulfide bonds.
