2.2 Variation and interdependence

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1 1 of 5 The National Strategies Secondary 2.2 Variation and interdependence 7 describe how organisms can vary and how this may lead to their survival in changing environments describe how the major taxonomic groups are classified use a combination of food chains within a habitat to produce food webs 8 explain how variation has benefits and limitations for the survival of organisms in specific habitats describe some examples of variation arising from inherited and environmental factors recognise how organisms that belong to the same species share many characteristics use data to describe common features of some of the main taxonomic groups of animals and plants, e.g. mammals, flowering plants construct and explain food chains and webs describe and explain examples of simple adaptations of plants and animals to different environments, and how they increase survival describe differences in organisms of the same species and attribute these either to environmental or to inherited factors Explore how simple models can be used to explain how adaptations to an environment increase survival, e.g. using forceps in a test tube to model the shape of an oystercatcher s bill and discussing how this increases survival rate in shallow water, but not on land; or using inverted cones of various paper thickness to represent adaptations of limpet shells (Patella vulgaris) across tidal zones. Create opportunities for pupils to discuss the advantages and disadvantages of the energy arrow model, and use this to explain how energy is transferred along a food chain and through food webs. Support pupils in exploring possible misconceptions they might have about ecosystems and adaptation. Create experimental opportunities for pupils to assess the risks involved in collecting and analysing living or dead material for classification, e.g. collecting owl pellets, observing wildlife on the school field, gathering evidence from pond dipping. Plan opportunities for pupils to discuss and explain patterns in primary environmental data. Plan opportunities to research and discuss the scientific evidence supporting a controversial topic, such as the development and use of Genetically Modified (GM) tomatoes. Model for pupils how to distinguish between scientific data and opinion when discussing headlines such as Obesity is inherited from parents or All pesticides should be banned. Encourage pupils to offer reasons to explain the link between the evidence and the conclusion, e.g. pollutant? Is energy made? Where does all the energy go? Is there any truth in the saying Like father like son? n animal? plant? What does disease do to a food web? Are green plants important? Are all ecosystems the same? superbug? Will nutrients run out? Do all living things die?

2 2 of 5 The National Strategies Secondary explain energy transfer in food chains and webs and relate this to the abundance of organisms use different models and analogies to describe the flow of energy through food chains and food webs, and relate this to energy transfer and why plants are essential to food chains researching the link between the distribution of dark fur on the paws, tail and face of Siamese cats where the body is cool. Structure opportunities for pupils to offer scientific reasons for the changes in the human population. Involve pupils in assessing how well different models can be used to explain how internal and external factors can affect energy transfer in food chains and webs. Create experimental opportunities for pupils to plan and carry out environmental investigations in situations where the variables are less easy to control. Are bacteria dangerous? 9 explain how variation in organisms can be artificially induced and the effect of these organisms on the environment explain how internal and external factors can affect energy transfer in food chains and webs analyse a range of evidence that aids the identification and classification of plants and animals describe ways to induce variation artificially, e.g. selective breeding, cloning and genetic engineering, and explore related issues use a range of examples to explore the impact of external and internal factors on the interdependence of organisms, e.g. poisons, disease, food shortages Create opportunities for pupils to discuss and compare different models used to explain the same process, e.g. the inheritance of gender or tongue rolling, and decide if it is a good enough model. Explore with pupils how diagrams in different textbooks show the same concept but could lead to misconceptions, e.g. scales used in diagrams such as pyramids of numbers and biomass or directional arrows on food webs. Involve pupils in identifying and presenting scientific arguments for a specific audience around a controversial issue, e.g. the use of myxomatosis to control rabbits or banning whale hunting. Provide pupils with structured opportunities to explore how the combined effects of changes to genes and environmental change can lead to variation in a species. Does sexual reproduction mean a longer life? Would the world exist without humans? Is eating important? Are patterns useful to animals? Are plants always environmentally friendly? 10 explain how the combined effects of changes to genes and use a range of models and analogies, e.g. Punnett diagrams or probability, to explain how Create opportunities to compare the scientifically accepted explanations with those that may lead to common misconceptions, e.g. by comparing Why do giraffes have long necks?

3 3 of 5 The National Strategies Secondary environmental change can lead to variation in a species explain the fluctuations in distribution and population size using: energy flow pyramids of number and biomass predator/prey 11 apply and use their knowledge of variation and interdependence to explain: genetic variation arises use and apply these models to explain how environmental differences can affect the expression of genes, e.g. effect of acidity on colour of hydrangeas, effect of temperature on the colour of fur of mammal such as stoat use models and analogies to explore energy transfer and efficiency within an ecosystem and explain how efficiencies may be increased interpret and evaluate models such as pyramids of numbers and biomass as a way of representing feeding in a habitat synthesise a range of secondary evidence to explore the fragility of the interdependence in an ecosystem, and how this affects the distribution and population size of organisms synthesise ideas and evidence to explore natural selection and its impact on variation in species evaluate fossil evidence to suggest reasons why some different theories of evolution and link this to the evidence needed to disprove it. Create opportunities for pupils to use a trend or pattern in results to make a prediction, e.g. about how the modern horse might evolve in the future based on the use of data from fossil remains (teeth, limb length) of extinct horse-type mammals, or to suggest how other extinct forms may be related to the modern horse. Create opportunities for pupils to present a complex scientific case persuasively enough to influence the responses of others using a topical environmental debate, e.g. culling of badgers to prevent spread of bovine tuberculosis. Provide pupils with the opportunities to research and evaluate sources of data from the internet about the discovery of a new species/order, e.g. the order Mantophasmatodea (Gladiator insects). Plan structured whole-class discussion on some of the sex-linked diseases, e.g. haemophilia, and suggest why scientists have not been able to eliminate these. Involve pupils in discussing the role of science in solving problems and the range of issues that can arise as a result, e.g. human embryology and fertilisation issues. Provide opportunities for pupils to explain the interplay between scientific theory and evidence in the discovery of Mendel s laws of inheritance. Create opportunities for pupils to devise criteria and evaluate claims made in the media and scientific articles, e.g. about allowing pregnancies of designer siblings to provide organs or tissues for transplantation. Was Darwin right? species? Should we all become vegetarians? Should we screen for inherited diseases? Does the environment cause evolution? Should badgers be culled? Does evolution always produce better organisms? Should there be

4 4 of 5 The National Strategies Secondary natural selection the applications and implications of artificial selection evolutionary and ecological species have adapted over time and why others have become extinct explain, with examples, how the classification of an organism may change in the light of new evidence explain how alternative forms (dominant and recessive) of a gene (alleles) cause variation in a characteristic evaluate different models and analogies to explain how sexlinked diseases occur and can be screened for explain why developments in genetic fingerprinting are now used to assist the identification and classification of organisms explain the benefits and drawbacks, including ethical, moral, social and political aspects, of some applications and implications of science, e.g. maximising human food production through genetic engineering, selective breeding and cloning evaluate the ethical and moral considerations in genetic manipulation and cellular approaches to artificial selection Provide opportunities for pupils to evaluate other pupils research to explain the impact of human activity on a topical environmental issue, e.g. species extinction or global warming. Create opportunities for pupils to analyse and evaluate data related to the beneficial and adverse effects of humans on the environment. Explore with pupils a range of associations between species, such as symbiosis and parasitism. a national DNA database? Extension apply and use their extensive knowledge synthesise ideas and evidence to evaluate critically the positive and

5 5 of 5 The National Strategies Secondary of variation and interdependence to explain and critically evaluate the impact of human activity on evolutionary and ecological negative impacts that humans have had on ecological, including extinction