Life Science Grade 11

Grade 11 Life Sciences Lesson Planssystem and reproductive system lie in the coelom.• Some animals such as jelly fish, hydra and tapeworms have onlyone opening for both ingestion of food and the egestion ofundigested material (blind gut)• As a result there is mixing of undigested and digested material,making it less specialized with no region of the gut having aspecific function• Some animals have two digestive openings allowing one-waymovement of food into the mouth and out of the anus (throughgut)• This has the advantage of moving food in only one direction somixing of undigested and digest food occurs• This allows specialization of the gut so different regions areadapted for specific functions, leading to greater efficiency• Digestion is able to take place continuously• If an animal has a surface area: volume ratio which is low they areable to move substances across the cells effectively using theprocess of diffusion. (In the next lesson we will look at surfacearea: volume). However, in many multicellular organisms diffusionwould be an inefficient way of transporting substances which hasled to the development of blood systems.• Open blood circulatory systems have blood vessels which areopen at both ends e.g. in Arthropods. Blood leaves the vesselsand flows into a body cavity called a haemocoel and then backinto the vessels at their other end.• In closed blood circulatory systems the blood stays in a vessel andthere is usually a pump moving blood around the system e.g.chordates.2.3 ConclusionRecap on what is meant by the following terms:Coelom, acoelomate, diploblastic, triploblastic, blind gut, throughgut, open circulatory system, closed circulatory system.Learners listen to classdiscussion asking andanswering questions.Learners write notes onwhat a blind and throughgut are.Learners listen to classdiscussion asking andanswering questions.Learners write notes onan open and closedcirculatory system.Learners providedefinitions to variousterms.10 min10 min10 minSolutions for all p94Understanding Life Sciences p89-90Solutions for all p95Understanding Life Sciences Activity 1.3.2 p90HomeworkActivity on body plan of organisms.Reflection / Notes:Term 1 Page 66© Gauteng Department of Education (CAPS version)