The membrane is selectively permeable because substances do not cross it indiscriminately. Some molecules, such as hydrocarbons and oxygen can cross the membrane. Many large molecules (such as glucose and other sugars) cannot. Water can pass through between the lipids.
a. chloroplast and cell wall
The chloroplast contains chlorophyll, which is the stuff that makes plants green. So animals do not have a chloroplast. Only plants have a cell wall and it is what helps plants maintain their shape. Hope this helped! :)
<span>Each of the protein chains are conjugated to a nonprotein heme group.Hemoglobin is
the protein that's made of the four polypeptide chains. Each of these chains contains a heme group. Red blood cells are primary players in the oxygen hauling, and they wouldn't be able to do their job if it the weren't for a special molecule called the heme.</span>