Organsms

• multicellular: made up of many types of cells, the cells are grouped together and perform specialised functions, specialised cells cant live independently of the organism
• unicellular: contains only one cell, can be prokaryotic or eukaryotic
• colonial: made up of identical single-celled organisms, individual cells are capable of carrying out all life processes required for survival
• multicellular-rats: made up of many specialised cells that would be unable to survive on their own.

  the individual cells are small which increases SA:V ratio which increases the efficiency of diffusion and osmosis.

  the cells are grouped by type, forming tissues such as skin tissue.

  tissues are in turn organised into organs and systems such as the digestive system responsible for nutrient uptake.

  embryotic cells develop structural changes as they grow and develop becoming specialised cells.
• unicellular-paramecium: single celled eukaryotic organism.

  ranges in size from 50-300um.

  feeds through endocytosis.

  the paramecium is responsible for its own life process; everything the paramecium needs to live must be undertaken by one cell.

  high SA:V ratio allowing for efficient diffusion of necessary materials through the cell membrane.
• colonial-sea sponge: made up of many choanocytes which each have a flagellum.

  sea sponges feed by filtering water.

  by working together, the many choanocytes are able to make a steady current through the sponge.

  each member of the colony are able to carry out necessary life processes.

  some colonial organisms contain specialed cells allowing for greater efficiency overall.
• choanocytes: a type of cell that lines the interior of sponges. It has a flagellum, surrounded by a collar of microvilli
• microvilli: any of numerous microscopic bristlelike protrusions that occur on the surface of a wide variety of cell types