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Delivery guides are designed to represent a body of knowledge about teaching a particular topic and contain:
- Content: A clear outline of the content covered by the delivery guide
- Thinking Conceptually: Expert guidance on the key concepts involved, common difficulties students may have, approaches to teaching that can help students understand these concepts and how this topic links conceptually to other areas of the subject
- Thinking Contextually: A range of suggested teaching activities using a variety of themes so that different activities can be selected which best suit particular classes, learning styles or teaching approaches.
Content (from AS and A-level)
The content from the specification that is covered by this delivery guide is:
|(a)||how biodiversity may be considered at different levels||To include habitat biodiversity (e.g. sand dunes, woodland, meadows, streams), species biodiversity (species richness and species evenness) and genetic biodiversity (e.g. different breeds within a species).|
|(b)||(i) how sampling is used in measuring the biodiversity of a habitat and the importance of sampling
(ii) practical investigations collecting random and non-random samples in the field
|To include how sampling can be carried out i.e. random sampling and non-random sampling (e.g. opportunistic, stratified and systematic) and the importance of sampling the range of organisms in a habitat.
M0.2, M1.3, M1.5, M1.4, M1.6, M1.7, M1.9, M1.10, M3.2
HSW4, HSW5, HSW6
|(c)||how to measure species richness and species evenness in a habitat||M1.1, M1.5, M2.3, M2.4|
|(d)||the use and interpretation of Simpson’s Index of Diversity (D) to calculate the biodiversity of a habitat||To include the formula:
D = 1–(Σ(n/N)2)
the interpretation of both high and low values of Simpson’s Index of Diversity (D).
M1.1, M1.5, M2.3, M2.4
|(e)||how genetic biodiversity may be assessed, including calculations||To include calculations of genetic diversity within isolated populations, for example the percentage of gene variants (alleles) in a genome.
proportion of polymorphic gene loci = number of polymorphic gene loci/total number of loci
Suitable populations include zoos (captive breeding), rare breeds and pedigree animals.
M1.1, M1.5, M2.3, M2.4
|(f)||the factors affecting biodiversity||To include human population growth, agriculture (monoculture) and climate change.
M1.3, M1.7, M3.1
HSW5, HSW10, HSW12
|(g)||the ecological, economic and aesthetic reasons for maintaining biodiversity||• Ecological, including protecting keystone species (interdependence of organisms) and maintaining genetic resource
• economic, including reducing soil depletion (continuous monoculture)
• aesthetic, including protecting landscapes.
|(h)||in situ and ex situ methods of maintaining biodiversity||• In situ conservation including marine conservation zones and wildlife reserves
• ex situ conservation including seed banks, botanic gardens and zoos.
HSW7, HSW9, HSW10, HSW12
|(i)||international and local conservation agreements made to protect species and habitats.||Historic and/or current agreements, including the Convention on International Trade in Endangered Species (CITES), the Rio Convention on Biological Diversity (CBD) and the Countryside Stewardship Scheme (CSS).
Biodiversity is one of the biggest current issues in biology and should be considered as one of the most fundamental topics. As such it provides a number of specific challenges to teachers, including:
- inspiring students with enthusiasm for the natural world and an appreciation of its importance to humans
- supporting students with little background knowledge or experience of examples of species or habitats
- ensuring that the clarity and precision of language used to discuss biodiversity topics is equivalent to that used to discuss other A Level topics such as biological molecules.
Students are likely to have studied the environment at GCSE or before and most will have some awareness of the term biodiversity, random sampling with quadrats and the idea of conservation. However, the demands of the A Level specification are distinctly higher than GCSE and it may be best to begin teaching it with the assumption that everything needs to be taught as if for the first time.
The biodiversity topic does provide an opportunity for students to develop some of the practical skills required by Module 1 of the specification and to develop many of the mathematical skills listed in specification section 5e.
Introducing students to the definition of biodiversity at three different levels can be done in general terms or using specific examples. Students are likely to be comfortable with the species level of biodiversity.
Domestic dogs, with their large variety of breeds, can be used as an example of a species with high genetic diversity. Cheetahs are homozygous at almost all gene loci and are therefore an example of a species with low genetic diversity. This is a good point at which to introduce the idea of measuring the level of genetic diversity within a population (4.2.1e) and the opportunities for students using mathematical skills (M1.1, M1.5, M2.3, M2.4) it provides.
The habitat (or ecosystem) level of diversity is harder to exemplify but a domestic house and garden, with a lawn, pond, border, patio or decking and of course the house itself, represents a relatively small area of land with a large variety of habitats.
Many biology teachers lack confidence in teaching sampling techniques and there are many external courses available from providers such as the Field Studies Council. However, these might be better done as part of Module 6. Many local independent providers also exist, often at only a small cost, for example:
It is not always appropriate to take students out of school. The requirements of Module 4 can be taught fairly easily with a basic knowledge of sampling techniques. No specific techniques are listed in the specification but it is reasonable to expect students to have used a quadrat to carry out both random and systematic sampling and to have considered the limitations of quadrat sampling e.g. quadrats are not suitable for counting trees or most animals.
Practical sampling activities can be carried out on any school field or local park. Random sampling using randomly generated coordinates and systematic sampling using a transect satisfies the requirements of the specification. A spreadsheet could be used to process class results and data generated using random sampling could be used in later lessons to calculate Simpsons Index of Diversity (4.2.1d).
Carrying out any of these practical activities could support the OCR Biology Practical Endorsement (PAG3) and could cover the following learning outcomes:
- From Module 1: 1.1.1 (a-c), 1.1.2 (a,c), 1.1.3 (a-c), 1.1.4 (a-e), 1.2.1 (a-g) and (j), 1.2.2 (k-l) and (f).
- From How Science Works: HSW4, HSW5, HSW6.
- From the list of mathematical skills: M0.2, M1.3, M1.4, M1.5, M1.6, M1.7, M1.9, M1.10, M2.3, M3.2.
Calculating species richness and evenness can be done as part of a random sampling procedure and covers mathematical skills M1.1, M1.5, M2.3, M2.4.
In class, discussion of richness and evenness could be based upon two areas, visually represented as squares on a screen or board, both of which have the same total number of species, but one is dominated by large numbers of one species.
There are many worked examples of calculating Simpson’s Index of Diversity available in textbooks or on the internet.
Provides a worked example with discussion of richness and evenness.
Students can then practise calculating Simpson’s Index from their own data from fieldwork or secondary data from other sources. At this point mathematical skills M1.1, M1.5, M2.3 and M2.4 can be covered, as can HSW5.
Factors that affect biodiversity and reasons for conservation can be discussed before researching on the internet.
Having generated lists of factors affecting biodiversity and reasons for conservation, students can then rank the significance of these in the context of a selection of endangered species given by the teacher (see further activities for suggested resources).
This site focuses on the conservation role of the millennium seed bank.
Students could research the millennium seed bank online or visit a local botanic garden.
Website for CITES.
Having researched conservation agreements, students could construct a table or Venn diagram showing main points, similarities and differences between each agreement.
Website for Rio Convention on Biological Diversity.
Website for information on the Countryside Stewardship Scheme, which ran from 1991 – 2014.
You may also find the new Natural England site useful.
Each student, or group of students, is given a species to research and a list of criteria that cover learning objectives (f) to (i). They then present their findings in an appropriate format.
There are many species that would be suitable and many sites that list them. One example of a list site is:
One specific example is the great bustard.
Approaches to teaching the content
Students inevitably have some prior knowledge and understanding of conservation and sampling techniques. It is possible therefore, to teach the topic from the top down, beginning with a location or species and visiting all the learning outcomes in context. This can be engaging and interesting for students and can help them relate the learning outcomes to a wider context. However, this approach can be at the expense of a rigorous understanding of key terms and the ability to describe concepts using precise language. It is essential, at some point, to reinforce the use and understanding of key terms and definitions.
Common misconceptions or difficulties students may have
The whole topic of biodiversity is steeped in context and most students begin the course with little contextual knowledge or understanding. Lack of familiarity with any species, other than Homo sapiens, makes the understanding of contextual examples of biodiversity doubly difficult. It is not surprising to find students who think a vulture is a mammal and students’ knowledge of plant based examples is even weaker.
The other main difficulty students have is in using key terms correctly and using clear and precise language in examinations. This can be a problem for some students in many areas of biology but it is particularly evident in biodiversity. Many students use terms such as biodiversity, habitat, ecosystem, environment, population and community as synonyms for one another.
Conceptual links to other areas of the specification – useful ways to approach this topic to set students up for topics later in the course
When individual species or habitats are considered there are links to many learning outcomes, for example 3.1.3(e) and 5.1.1(d). However, the topic of biodiversity necessarily overlaps with 4.2.2 in the same module and both should be taught in a complementary fashion. Future topics with significant contextual links are 6.3.1 in its entirely and 5.2.1(g), 6.1.2(a, e-h), 6.1.3(g), and 6.2.1(f, h).
When studying any particular species or habitat the ideas of adaptation and selection pressure can be introduced to complement teaching of 4.2.2.
The biodiversity topic is almost inevitably taught in context. Indeed the ideas contained in most of the learning outcomes make little sense outside a specific context – examples are needed at all stages. Examples can be found at a local level: within school grounds or, if conveniently situated, botanic gardens or nature reserves. The internet contains many worldwide examples; as we all live on the same planet it is important that students appreciate the global nature of biology.
Giving each student or group of students a particular species or ecosystem to research can introduce students to a number of relevant examples and make them more comfortable about applying their knowledge and understanding to unfamiliar contexts. Some potential sources of information at a local, national and international level are shown in the activities, but there are many more available.
Having been introduced to a range of examples, students can then relate each of the learning outcomes to the context of the examples being discussed.
OCR’s resources are provided to support the teaching of OCR specifications, but in no way constitute an endorsed teaching method that is required by the Board and the decision to use them lies with the individual teacher. Whilst every effort is made to ensure the accuracy of the content, OCR cannot be held responsible for any errors or omissions within these resources. We update our resources on a regular basis, so please check the OCR website to ensure you have the most up to date version.
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