12/11/151.1: Introduction to CellsSoniya NahataIB Biology (SL)Essential idea:The evolution of multicellular organisms allowed cell specialization and cell replacement.Understandings:U1.According to the cell theory, living organisms are composed of cells.Every living cell is surrounded by a membrane, which separates the cell contents from everything else outside.Cells contain genetic material, which stores all of the instructions needed for the cell’s activities.Many of these activities are chemical reactions catalyzed by enzymes made inside the cell.Cells have their own energy release system, which powers all of thecell’s activities. Cells multiply through division. Mitosisresults in genetically identical daughter cells.Meiosis generates haploid gametes (sex cells).U2.Organisms consisting of only one cell carry out all functions of life in thatcell.For organisms that contain only one cell, a single cell will carry out all the functions of life. This means that the structure of a unicellular organism is more complex that of a multicellular organism. These functions are (MR H GREN):Metabolism:oThe web of all the enzyme-catalyzed reactions in a cell or organism. E.g. respiration.Response:oLiving things can respond to and interact with the environment.Homeostasis:oThe maintenance and regulation of internal cell conditions, e.g. water and pH.Growth:oLiving things can grow or change size/ shape.Reproduction:oLiving things produce offspring, either sexually or asexually.