All cells are enclosed with a cell membrane. A selectively permeable cell membrane is one that allows certain molecules or ions to pass through it by means of active or passive transport.
Answer:
yes , all atoms are joined
together by chemical bonds
Answer:
In summary, a polar bond results when different atoms share electrons. One atom will attract the bonding electrons more strongly than the other atom and will acquire more than a half share of these electrons. This leaves the other atom with less than a half share and makes the electron distribution unsymmetrical. On a time-average basis the electrons spending more time with one atom and cause it to have a partial negative charge. The other atom, deficient in electrons, acquires a partial positive charge.
This is because the relative atomic mass is the sum of the no of protons and neutrons while the atomic no is of the former only. it is not a whole number it is th average weighted masses of the various isotopes of the element multiplied by their corresponding relative abundance. pls thank me and mark me briniest