| Growth and Cell Size |
| The four processes Diffusion, Active Transport, Passive Transport, and Osmosis have already been covered by the class. They will now see how these processes determine the manner in which multi-cellular organisms grow. From last class: Diffusion, Active Transport, Passive Transport, and Osmosis -these are the four processes used by the cell to obtain food, water, and oxygen and to get rid of wastes -all four involve movement of molecules, a process that takes time -e.g. a waste molecule must move across the cell, through the membane, and away from the cell -cells that are too big will die: -the bigger the cell, the longer it takes -larger cells need more food and produce more waste Growth and Repair: all plants and animals must do this -examples: a baby must grow to become an adult tissues must be repaired after they are damaged How do growth and repair occur? Since plants and animals are made up of cells, the cells must change in order for the organism to grow. Does every cell get bigger and bigger? No, because the cells would die. Can more cells be made? Yes. Organisms make more cells in order to grow. -more cells are made using cell division -copying of cells that already exist -think of it as making photocopies -this copying process is called MITOSIS |