B4.1d - B4.1f Factors affecting ecosystems
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B4.1d - B4.1f Factors affecting ecosystems
BM4.1i Calculate the percentage of mass
BM4.1ii Plot and draw appropriate graphs selecting appropriate scales for the axes
B4.1d describe different levels of organisation in an ecosystem from individual organisms to the whole ecosystem
B4.1e explain how abiotic and biotic factors can affect communities to include temperature, light intensity, moisture level, pH of soil, predators, food
B4.1f describe the importance of to include interdependence and competition in a community interdependence relating to predation, mutualism and parasitism
Although learners will have come across some of the basic ideas covered in this topic e.g. predators and prey, parasites, habitats etc. the increase in detail and key vocabulary is quite large. It is therefore important to build numerous short, fun activities to introduce new vocabulary and to revisit these terms throughout the topic to reinforce learning.
Practical work sampling the biotic factors in two areas of their school field in addition to as many abiotic factors your school equipment will allow, will help reinforce the concept of abiotic and biotic factors both of which will be new to learners.
Interdependence and competition in a community lends itself well to using visuals to engage learners as there are numerous video clips on the internet showing predators catching prey, parasites, competition between two species etc. on the National Geographic Channel website and most David Attenborough box sets, the most recent one 'The Hunt' being perfect for this.
Common misconceptions or difficulties learners may have
Learners at more urban schools often do not realise that their location is a habitat. The urban habitat can provide a rich variety of abiotic and biotic factors enabling the community to thrive – talk to the school caretaker to find out what animal species they have to control. This link shows how many insects can be found in a typical house. Sampling an urban environment is possible and the results compared to a rural school to show reinforce the difference in habitats.
Learners can often have difficulty understanding the concept of the term 'niche'. They often see it as being a smaller physical space where something lives e.g. under a rock within a habitat. Using examples of organisms with very similar niches e.g. red and grey squirrel, learners can discuss all of the similarities between the niches (i.e. same food source, time of activity, shelter/nesting etc.) and the result being that without human intervention the red squirrel would probably be extinct by now. Compare this with two organisms with niches that overlap slightly e.g. chipmunk and squirrel and learners should be able to see that there are a number of factors that affect both organisms, but differences in nesting/shelter allow slightly less competition therefore a slightly increased chance of both surviving. Learners should now be aware that a niche involves all of the factors discussed. Urban habitats do provide a number of examples of organisms with similar niches.
Learners should also be aware of interactions between two species where one species benefits and the other is harmed in some way e.g. predator and prey or parasite and host. They often do not realise that there are other interactions that benefit both species. This is covered in activity 6 of this delivery guide.
Conceptual links to other areas of the specification – useful ways to approach this topic to set learners up for topics later in the course
Learners may carry out a brief investigation sampling biotic factors in an ecosystem. This will be developed further in B6.1 where learners will learn to explain how to carry out field investigations into the distribution and abundance of organisms in a habitat.
Learners will have a good knowledge of the various interactions between species in an ecosystem which is a good foundation for understanding how interactions such as competition may lead to evolution of a new species through natural selection in B5.2. It also links to B6.1b where learners will explore interactions between humans and other organisms in an ecosystem further.
Approaches to teaching the content
Carrying out sampling using quadrats to compare two areas of their school field and other equipment to measure abiotic factors not only helps in learners understanding of the topic content, but reminds learners that ecosystems are all around them, habitats are not places they have to travel to the countryside to see. It also enhances team work and organisational skills and allows learners to plan their own investigations, write methods, results tables and graphs, draw conclusions and evaluate their work which are important skills to improve throughout future topic areas.
A graphic organiser for learners to complete with definitions and images for the key vocabulary describing different levels of organisation in an ecosystem such as species, population, community etc.
Give learners a choice of ecosystems to research e.g. marine, forest, pond, desert, rainforest, forest etc. Learners research definitions of each keyword on the graphic organiser and write it in the relevant box. They then find an example of each from the ecosystem they have chosen and name and draw images to show these in the relevant boxes next to the definitions.
A PowerPoint presentation about how abiotic and biotic factors affect communities including information, short activities and questions for learners.
Teachers may want to remove the slides referring to climatic and edaphic factors. They may also want to adapt some slides or remove/add their own slides.
A 60 minute lesson that can be used to deliver the interactions between different species within a community.
The lesson includes a starter, a main activity where learners simulate the different relationships in a community by representing different species competing for food (beads), a plenary and extension task.
Two video clips from David Attenborough's 'The Hunt' that are great to show the class as an introduction to the relationship between predators and prey. (Teachers may want to warn learners that the videos contain an animal be hunted and caught by another before showing the clips).
Once learners have seen the clips, discuss as a class the features a predator and a prey would have and why e.g. positioning of eyes, teeth, claws, camouflage etc. (don't forget to include birds).
Learners may then be allocated different habitats and design a predator and a prey for that habitat. They then present their organisms to the class explaining how their features allow them to carry out their role.
A fox and rabbit predator prey game where learners drop 'fox' cards onto a table 'meadow' to catch 'rabbits'. Results are recorded over numerous 'years' and the population sizes are plotted on a graph.
After the game, teachers may want to project the 'Predator-prey graph activity' on the whiteboard for learners to complete.
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