Some macromolecules are formed from one or two or small molecular fragments that repeat. a) amino acid b) monomer c) polymer d) string

The macromolecules are formed with B) monomers.

A macromolecule is an exceptionally huge particle, for example, protein, usually made by the polymerization of littler subunits called as monomers. They are normally made out of thousands of iotas or more.

The most well-known macromolecules in organic chemistry are biopolymers (nucleic acids, proteins, and sugars) and enormous non-polymeric particles (for example, lipids and macro cycles). Manufactured macromolecules incorporate normal plastics and engineered filaments just as test materials, for example, carbon nanotubes.

Amino acids are monomers of proteins; polymer refers to the chain which is formed by more than one monomer.

B) monomer

Explanation:

Monomers are small molecules capable of binding with other monomers, resulting in macromolecules (which may also be called polymers). Basically monomers are the raw materials of macromolecules, they are simple molecules, usually organic, which when grouped over and over, can be the same molecules or arranged with molecules of other compounds, form long chains called polymers.

nucleus

would be most reasonable answer tbh

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!