Theory question 101
Cell Structure and Organisation(a) State two advantages of complex structural organisation in higher organisms
(b) (i) List two differences between colonial organisms and filamentous organisms (ii) Give one example each of a colonial organism and a filamentous organism
(c) Make a labelled diagram 10-12cm long to show the structure of a named filamentous alga.
Show the model answer
(a) Any two: division of labour – cells specialised for particular jobs work more efficiently; larger size possible; better adaptation to varied environments; internal environment controlled (homeostasis); organs and systems allow faster transport and coordination
(b)(i) Colonial: cells grouped in a ball/cluster; cells often similar and can live independently; some division of labour (e.g. reproductive cells in Volvox); Filamentous: cells joined end to end in a chain; all cells similar; little or no division of labour
(ii) Colonial – Volvox (or Pandorina); filamentous – Spirogyra (or Ulothrix, Oedogonium)
(c) Spirogyra, 10–12 cm drawing with title: cell wall, mucilage layer, spiral chloroplast(s), pyrenoids, nucleus held by cytoplasmic strands, large vacuole, cross wall between cells
Give the drawing a title and keep it the required size.