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Plasma membrane

• Plasma membrane is the outermost layer in cells.
• It separates the content of cell from their external environment.
• It allows the materials from surrounding to enter and exit the cell. It also allows the materials from cell to exit outside.
• It controls the entry and exit of materials in nd out of cell and hence it is called selectively permeable membrane.
• Gases like carbon-dioxide or oxygen can also move in or out from high concentration to low concentration in a cell through the cell membrane by the process of diffusion.
• It also allows the movement of water in and out of the cell depending upon the concentration outside the cell by the process of osmosis.

 Nucleus

• The nucleus is small, round and membrane bound structure found in cell.
• The fluid inside the nucleus surrounded by nuclear membrane is called nucleoplasm.
• It controls the cell’s growth and reproduction because it contains cell's hereditary information.
• It is covered by dual layer called nuclear membrane.
• The nuclear membrane contains pores due to which materials can travel both inside the nucleus from its outer surrounding i.e. cytoplasm.

Cell wall

• Cell Wall is found in plant cells outside the plasma membrane.
• It is a rigid covering made up of cellulose which a complex substance is providing structural support to the plants.
• The contents of the cell wall contracts during loss of water in plant cells by the process of osmosis.
• Due to the presence of cell wall plant cells can withstand greater changes in the surrounding media due to the exertion of equal pressure to the cell when it swells up by taking up water through osmosis in a hypnotic media.