Answer:
1. It is present as the outermost layer in animal cells and lies below the cell wall in plant cells.
2. The cell membrane surrounds the cytoplasm of living cells, physically separating the intracellular components from the extracellular environment.
3. The cell membrane is semi-permeable, ie, it allows some substances to pass through it and does not allow others.
Explanation: The cell membrane (or plasma membrane) surrounds all living cells, and is the cell's most important organelle. It controls how substances can move in and out of the cell and is responsible for many other properties of the cell as well.The membranes that surround the nucleus and other organelles are almost identical to the cell membrane. Membranes are composed of phospholipids,proteins and carbohydrates arranged in a fluid mosaic structure,