GCSE Biology: Exchange and transport in animals
Having understood how substances are transported into and out of cells, GCSE Biology students need to be able to explain the need for exchange surfaces and transport systems in multi cellular organisms. Students need to be able to explain this in terms of surface area to volume ratio, and be able to calculate this ratio. Students need to describe some of the substances transported into and out of a range of organisms, in terms of the requirements of those organisms , this should include the transport of oxygen, carbon dioxide, water, dissolved food molecules, mineral ions and urea.
Students commonly show confusion regarding surface area: volume ratio, as this is an important concept it is worth spending some time ensuring that students have fully grasped this concept and have the required maths skills to complete calculations. Active practical activities, such as those using agar jelly cubes are useful to develop understanding of this concept
Students find it particularly difficult to grasp how larger animals have a smaller surface area: volume ratio, so the use of a variety of teaching strategies including practical activites, modelling , and animations would be useful.
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