1. The cell
Cell wall :
• In plants, one another rigid is called 'Cell wall'. It is made up of cellulose which provide structural strength to plant.
Function of cell wall :
• It maintains the shape of cell.
• It protect the cells from mechanical injury & prevents their desication.
• It provide mechanical support against gravity. It is due to rigid cell walls that the aerial part of plant are able to keep erect & expose their leaves to sunlight.
• Cell walls permit the cells to with stand very dilute external media without bursting.