Ascientist is comparing the outer layer of an onion cell to the outer layer of a human skin cell. what is unique about the outer layer of the onion cell compared to the skin cell? it contains proteins. it contains cellulose. it contains carbohydrates. it is selectively permeable.

The correct answer is option It contains cellulose.

The cellulose is the component, which make up the cell wall of the plant cells. The cell wall made up of cellulose is an unique feature of the plant cells. It helps the plant to stand up straight against gravity by providing structural support. The cell wall is absent in the animal or the human cell, so, cellulose would not be find in human cell but it would be present in human cell.

the sugar-phosphate backbone forms the structural framework of nucleic acids, including dna and rna. this backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.