What you’ll learn19 learning objectivesChoose one objective for a focused lesson, or study the complete topic.19.2.1Food chain as showing the transfer• Describe a food chain as showing the transfer of energy from one organism to the next, beginning with a producerSyllabus objective19.2.2Construct and interpret simple food• Construct and interpret simple food chainsSyllabus objective19.2.3Food web as a network• Describe a food web as a network of interconnected food chains and interpret food websSyllabus objective19.2.4Producer as an organism that makes its• Describe a producer as an organism that makes its own organic nutrients, usually using energy from sunlight, through photosynthesisSyllabus objective19.2.5Consumer as an organism that gets its• Describe a consumer as an organism that gets its energy by feeding on other organismsSyllabus objective19.2.6Consumers may be classed as primary• State that consumers may be classed as primary, secondary, tertiary and quaternary according to their position in a food chainSyllabus objective19.2.7Herbivore as an animal that gets its• Describe a herbivore as an animal that gets its energy by eating plantsSyllabus objective19.2.8Carnivore as an animal that gets its• Describe a carnivore as an animal that gets its energy by eating other animalsSyllabus objective19.2.9Decomposer as an organism that gets• Describe a decomposer as an organism that gets its energy from dead or waste organic materialSyllabus objective19.2.10Food chains and food webs to describe• Use food chains and food webs to describe the impact humans have through overharvesting of food species and through introducing foreign species to a habitatSyllabus objective19.2.11Pyramids of numbers and pyramids• Draw, describe and interpret pyramids of numbers and pyramids of biomassSyllabus objective19.2.12Pyramids of biomass• Discuss the advantages of using a pyramid of biomass rather than a pyramid of numbers to represent a food chainSyllabus objective19.2.13Trophic level as the position• Describe a trophic level as the position of an organism in a food chain, food web or ecological pyramidSyllabus objective19.2.14Following as the trophic levels• Identify the following as the trophic levels in food webs, food chains and ecological pyramids: producers, primary consumers, secondary consumers, tertiary consumers and quaternary consumersSyllabus objective19.2.15Pyramids of energy• Draw, describe and interpret pyramids of energySyllabus objective19.2.16Pyramids of energy• Discuss the advantages of using a pyramid of energy rather than pyramids of numbers or biomass to represent a food chainSyllabus objective19.2.17Transfer of energy from one trophic• Explain why the transfer of energy from one trophic level to another is often not efficientSyllabus objective19.2.18Explain, in terms of energy loss, why• Explain, in terms of energy loss, why food chains usually have fewer than five trophic levelsSyllabus objective19.2.19It is more energy efficient for humans• Explain why it is more energy efficient for humans to eat crop plants than to eat livestock that have been fed on crop plantsSyllabus objective