Cell membrane called the selectively permeable membrane

1. Why should a magnesium ribbon be cleaned before burning it?

Ans: Every cell has a cell membrane that surrounds all the parts present in the cell. This membrane keeps the different parts of a cell together in a place and prevents the parts of the cell from going here and there. This membrane is also known as a selectively permeable membrane because this allows only certain materials to pass through it. This makes a cell a very advanced organism as it can decide on its own what materials it needs for survival and whatnot. A selectively permeable membrane is different from the one which is nonpermeable as a nonpermeable membrane does not allow anything to pass through it. A membrane doesn’t need to surround the cell. An example of a nonpermeable membrane can be paper, as it does not allow materials to pass through it.

A selectively permeable membrane such as a cell membrane allows only the selected materials to pass through it. These minerals are molecules of oxygen and hydrocarbons, and other important things a cell needs to survive. It allows the passage of these materials while restricting the movement of others. If the cell membrane was to be freely permeable, it would allow anything to pass through it, which might lead to the entrance of harmful substances into the cell leading to its damage. The plasma membrane of the cells, attributed to being selectively permeable, helps cells not only survive the harmful attacks of foreign substances but also supplies different materials to the cell. This property of the cell membrane makes it an important part of the cell. If the cell membrane had been nonpermeable or freely permeable, then the cell would not have survived. Hence cell membrane is a very important part of the cell.