Life Science Grade 11

Grade 11 Life Sciences Lesson PlansAfter 25 min the groups are to split up and reform into newgroups where each group includes one expert from each‘phylum’ group. Learners are to share their knowledge withthe new groups completing a table under the followingheadings:PhylumAnnelidaArthropodaChordataSymmetry andcephalisationNumberof tissuelayers.Coelomandbloodsystem.Diagramof ananimalfrom thephylum20 min • Internet ref with comparisontables:http://www.bclearningnetwork.com/LOR/media/BIO11/Worksheets_Update/U10L01_3ws.pdf• http://www.biologycorner.com/bio1/notes-arthropods.html• The following must be highlighted by use ofblackboard/transparencies and class discussion:Annelida• The phylum Annelida is made up of segmented wormssuch as earthworms, bristle worms and leeches• They are free-living and may be found in fresh-water ormarine environment or living in moist soil• Annelids exhibit cephalisation, having a concentrationof nerve cells at the anterior end (head)• Their bodies are segmented externally and internally andeach segment has a cross wall or septa separating itfrom the next• As a result of cephalisation and dorso-ventraldifferentiation, Annelids are bilaterally symmetrical (canbe cut into mirror images in one plane only along acentral longitudinal plane)• Annelids are triploblastic having developed fromembryonic tissues consisting of three layers• The ectoderm and endoderm become differentiated asthe Annelids reach maturity• Annelids have a true coelom within the mesoderm andare therefore coelomate• The digestive system has two digestive openings and is athrough gut (mouth and anus)• The advantages of the through gut is that food moves inonly one direction and there is no mixing of undigestedand partially digested food• The gut can become specialized so that digestion ismore efficient• Digestion may also take place continuously• A blood system provides transport of gases and foodTerm 1 Page 75© Gauteng Department of Education (CAPS version)