Biodiversity and Ecosystems

Transcription

1 Biodiversity and Ecosystems 1.1 Importance of Biodiversity 1.2 Parts of an Ecosystem 1.3 Stable Ecosystems (quick recap on food webs/chains here) 1.4 Sampling Ecosystems 1.5 Biological Keys 1.Biodiversity and Ecosystems Learning Intentions By the end of this section you should be able to: state what is meant by biodiversity explain the importance of biodiversity identify the parts of an ecosystem explain what makes an ecosystem stable design an investigation to sample plants and animals in an ecosystem use sampling equipment to estimate abundance identify possible sources of error when sampling ecosystems identify animals and plants using biological keys 1.1 Importance of Biodiversity Biodiversity is the total variety of living things in a given habitat or ecosystem. It is incredibly important as all living things interact with and rely on each other. Our quality of life and standard of living depend on maintaining biodiversity. Biodiversity is affected by biotic factors, e.g. grazing, predation and disease, abiotic factors, e.g. temperature, rainfall and ph, and by human influences such as air pollution, water pollution, habitat destruction, desertification and overfishing. 1

2 We obtain food from the wild (e.g. fish from the North Sea, red deer) or from crop plants (e.g., wheat and potatoes) and from domestic animals (e.g., cattle and poultry) which are descended from wild varieties. Plant and animal breeders and genetic engineers are continually producing new varieties (e.g., disease resistant crops) and rely on wild species as a source of genetic material. Wild species of plants and animals can be regarded as a sort of genetic bank. Wild plants are an important source of medicines (e.g., morphine from opium poppy). The current search for medicines to treat cancer and AIDS involves the sampling of the huge variety of plants not yet tested. Plants are also an important source of raw materials (e.g., wood, rubber and cotton). The countryside and its wildlife are enjoyed by people for recreation (e.g., hill walking and bird watching). The variety of plants and animals is an important part of this recreation. Learning Activity 1 Show you know! Explain what is meant by the term biodiversity. Explain why biodiversity is important for ecosystems and also for humans. Re-organise the information in the passage to create a table, using the headings below which shows the importance of biodiversity. Importance of Biodiversity Examples 2

3 1.2 Parts of an Ecosystem You will need to be confident using the vocabulary of ecology. The table on the next page contains words and definitions that you need to know. Learning Activity 2 Expand your vocabulary! Use your existing knowledge or class resources to complete the table Word Meaning Example Population Species Producer Carnivore Organism that feeds on plant material only Decomposer Organism that feeds on plant an animal material Ecosystem Learning Activity 3 Show you know! 1. Explain the difference between a population and a community. 2. Name the 2 parts which together make up an ecosystem. 3. Explain the difference between biodiversity and ecosystem. 3

4 Learning Activity 4 A Freshwater Ecosystem 1. Insert and complete the Freshwater Ecosystem diagram from your pack into your notes. 2. With reference to the freshwater ecosystem diagram, name the: 3 freshwater habitats Community found in each habitat Freshwater Ecosystem 4

5 1.3 Stable Ecosystems Ecosystems which contain a large biodiversity are very stable. The wider the range of organisms in a particular area, the more robust is the whole ecosystem making it less susceptible to damage. This stability ensures the survival of ecosystems and their species over long periods of time. Learning Activity 5 show you know! Imagine a situation in which all of the minnows in both ecosystems died from a disease. Describe the effect that this would have on the population size of the perch in the: small pond food web loch food web 5

6 Describe the effect that this would have on the population size of algae in the: small pond food web loch food web Identify which ecosystem is more stable and explain (in as much detail as you can) why it is more stable. 1.4 Sampling Ecosystems Sampling techniques are used to provide information on the biodiversity of an ecosystem by measuring the types and abundance of organism found in small areas of the ecosystem. Techniques used to estimate the abundance of organisms are known as quantitative techniques. Quadrats Quadrats are mostly used to estimate the population of particular plant species in a habitat but they can also be used to sample animals that are fixed in place (e.g. limpets stuck to a rock). Your teacher will demonstrate how to use a quadrat. Learning Activity 6 Show you know! Insert and complete the Measuring Abundance diagram from your pack. 6

7 Learning Activity 7 Investigating Plant Abundance Aim: To measure the abundance of two plant species living around the school grounds using quadrats (e.g. daisies and clover). Method: you must write a brief explanation of how you will carry out this investigation. You should describe how you will set it up, what equipment you will use, what you will measure and how you will make your results reliable. Results: Record your results in a table with these headings; Plant Species Abundance Average abundance Conclusion: You must make a statement about what the results tell you. This must be related to your aim. Evaluation: You should discuss at least one of the following: Limitations of using a quadrat Sources of error and what you did to minimise them (If you are stuck with this use p of NAT 5 Biology textbook) Extension Present you results as a bar graph. Use your results to calculate the average abundance of each plant species per m 2. 7

8 Assume the total area of the school grounds is 1000m 2. Use the results of your investigation to calculate the estimated population of each plant species that you have sampled. All lines must be drawn in pencil with a ruler The labels for the Y (vertical) axis and X (horizontal) axis must match up to the headings in the table, including any units Each scale must have equal integers (i.e. each space on the scale should be worth the same numerical value) The bars should be accurately drawn, i.e. tops of the bars should be straight; bars should be same width; height of each Learning Activity bar 8 should Sampling match a Animals value given in the table The bar graph should have a title You will be given a set of equipment and the information card Success Criteria for a Bar Chart Sampling Techniques. The information card gives examples of various sampling techniques used to estimate the abundance of animals. You must use the information card to: find out what your equipment is used to sample find out how to carry out each technique find out any sources of error that could affect results and be able to describe how to minimise errors You must now explain this to the rest of the class. 8

9 Learning Activity 9 Show you know! Insert and complete the Sampling Techniques diagram from your pack into your notes. Learning Activity 10 Investigating a Woodland Ecosystem In your groups you will use one of the pieces of sampling equipment. Your teacher will choose an area for you to sample. Each group must record their results and share them with the rest of the class. You should decide the best way to do this. Biological Keys By now you will have collected different kinds of organisms, some of which you might not have seen before. What do you do if you can t identify them? Look at the two pictures below. Describe as many differences as you can between the appearance of the first insect and the second insect. 9

10 Biological keys use differences in the appearance of organisms to tell them apart and identify them. It is better to avoid using relative terms like big and small or thick and thin because if you are looking at a photograph it can be hard to tell how big or small something is! Look instead for things like number of legs or arms, shape of body parts or distinctive markings. Learning Activity 11 Paired Statement Keys Insert and complete the Paired Statement Keys Questions diagram from your pack into your notes. Learning Activity 12 - Extension Use your new found sampling skills to sample some organisms. Create a key to help someone else identify the organisms. Or 10

11 Use class resources to investigate different kinds of organelles and construct a paired statement key to identify at least four kinds of organelles. Choice Extension Task Choose at least two of the following activities to complete Completed 1 Research an organism that is under threat of extinction due to human activities. 2 Make a model of a food chain or food web. 3 Write a poem on biodiversity. 4 Make an educational video for 1st years, explaining food chains and food webs. 5 Design a questionnaire to investigate peoples knowledge on biodiversity and its importance. Self Evaluation - How well did I do? How well can you describe the key words/phrases below? Take turns at explaining what they mean to the person sitting next to you, and then let them explain them to you. Biodiversity, population, habitat, community, species, paired statement key, abundance, sampling, sources of error, decomposer, carnivore, omnivore, herbivore, producer, minimise, reliable, quantitative, quadrat Use the success criteria sheet to reflect on and evaluate your learning from this section. Think carefully and answer the following questions: 1. What skills have you developed over the past few lessons? How do you know and how could you prove it to someone? 2. What areas have you found difficult? What strategies are you going to use to overcome these problems? 11

12 Discuss this with your teacher and set yourself a learning target this is what you will do to improve your knowledge and skills. Update Didbook with a comment about what you have done well, what you want to improve at doing and how you will do this. 12