Which of the following best describes a process that helps a cell maintain homeostasis without requiring energy to be used? 1. Channel proteins provide a passage for molecules to cross the membrane via facilitated diffusion.
2. Membrane carrier proteins help substances enter the cell against a concentration gradient.
3. Pieces of the cell membrane for vesicles circulate around extracellular materials during endocytosis.
4.Protons are pumped out of the cell to create a voltage across the cell membrane.

What best explains whether bromine (br) or neon (ne) is more likely to form a covalent bond? bromine forms covalent bonds because it has seven valence electrons, but neon has eight valence electrons and already fulfills the octet rule. bromine forms covalent bonds because it has many electron shells, but neon has only two electron shells and is tightly bound to its electrons. neon forms covalent bonds because it can share its valence electrons, but bromine has seven valence electrons and can gain only one more electron. neon forms covalent bonds because it has only two electron shells, but bromine has many electron shells and will lose electrons in order to fulfill the octet rule.