Which of the following statements is correct regarding cell membrane?

I. The membrane is selectively permeable to some molecules present on either side of it.

II. Water may also move across this membrane from lower to higher concentration.

The correct answer is Only I.Key Points

• The cell membrane is a thin, flexible barrier that separates the inside of a cell from its external environment.
• It is selectively permeable, meaning that it allows some substances to pass through while preventing others from entering or leaving the cell.
• This selectivity is achieved through various mechanisms such as ion channels, transporters, and pumps.
• Water can also move across the membrane through a process called osmosis, but it always moves from an area of higher concentration to an area of lower concentration.

Additional Information

• The lipid bilayer that makes up the cell membrane is composed of two phospholipid layers with cholesterol, a lipid component, strewn in between to maintain the proper fluidity of the membrane at different temperatures.
• Additionally, membrane proteins are present in the membrane.
• These proteins include integral proteins, which span the membrane and function as membrane transporters, and peripheral proteins, which cling slackly to the cell membrane's outer (peripheral) side and function as enzymes to promote interaction with the surrounding milieu.
• The function of glycolipids embedded in the outer lipid layer is comparable. 
• Furthermore, cell membranes act as the attachment surface for a number of extracellular structures, including the cell wall, and are involved in a number of cellular activities including cell adhesion, ion conductivity, and cell signaling.