B4.1a - B4.1c Cycling of materials through an ecosystem
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B4.1a - B4.1c Cycling of materials through an ecosystem
BM4.1i Calculate the percentage of mass
BM4.1ii Plot and draw appropriate graphs selecting appropriate scales for the axes
B4.1a recall that many different materials cycle through the abiotic and biotic components of an ecosystem to include examples of cycled materials e.g. nitrogen and carbon
B4.1b explain the role of microorganisms in the cycling of materials through an ecosystem to include the role of microorganisms in decomposition
B4.1c explain the importance of the carbon cycle and the water cycle to living organisms to include maintaining habitats, fresh water flow of nutrients
This topic can be difficult for learners to fully understand as a number of the concepts cannot physically be seen i.e. the movement of carbon or nitrogen within the ecosystems and the microbes that are so important to this. It does however lend itself well to role playing with learners taking on the role of a carbon or a nitrogen atom and visiting different stations around the classroom such as air, plants, animals, oceans etc. to get an idea of the movement and cycling of materials.
There are also numerous animations on the internet that give learners a more visual picture of the carbon and nitrogen cycles as a whole as well as looking at different stages in more detail.
The carbon, nitrogen and water cycle have a number of sequential steps so activities involving card sequencing followed by drawing and annotating links between these stages can be useful for learners to visual the concept.
The B4 delivery guides have split the learning objectives into two separate sub-topics – this can provide suitable breaks for discussion or suitable practical activities. As the specification is linear, planning the order of learning objectives is at the discretion of the teacher.
Common misconceptions or difficulties learners may have
Learners often ask for the ‘definitive’ nitrogen cycle - unfortunately this does not exist. A simple internet search or a flick through past GCSE papers will confirm the plethora of nitrogen cycles. Learners should be taught to look at the information that is provided and devise a cycle from that. The LR1 that is included in this delivery guide does this well.
Learners will be aware of microorganisms causing disease but may not be aware that microorganisms play an important role in the continuous cycling of materials in an ecosystem. The activities in this delivery guide should address this.
Learners may also believe that decomposers transfer energy directly to plants rather than them breaking down dead organisms; returning nutrients to the soil so they can be used by plants. Teachers could address this by showing learners an image of an apple and a rotting apple. This will stimulate a discussion as to how this occurs and what will eventually happen to the apple.
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 will have studied the processes of aerobic and anaerobic respiration in plants, animals and fungi and also how enzyme activity is affected in B1.2 and B1.3. This should aid the understanding of the role microorganisms have in decomposing and materials and how the speed of that process can be changed.
Approaches to teaching the content
This topic lends itself to a range of 'hands on' activities from role playing to practical activities building mini ecosystems, growing microorganisms and composting plant material in various conditions. From this learners develop both investigative and mathematical skills in addition to encouraging a deeper understanding of the more complex aspects of the positive role of microorganisms in ecosystems rather than the negative disease causing role most learners associate with microorganisms.
The video clip for the 'Circle of Life' song at the start of the Disney film 'The Lion King'. This can be played as learners arrive at the classroom and settle at their desks.
If you have the DVD of the film, there is a short conversation Mufasa has with Simba about how lions eat antelope, but when the lions die, their bodies feed the grass that the antelope eat i.e. the Circle of Life. This is nice introduction to a discussion about the cycling of materials in an ecosystem at the start of the topic.
Lesson plan including background information about the cycling of carbon and a practical activity releasing carbon dioxide that could potentially have been breathed out by a dinosaur from chalk (instruction and learners worksheet included).
Possible teaching order:
1. Learners read through the ‘Student background reading sheet' and highlight the key points.
2. Carry out the practical activity and complete the worksheet.
3. Using the ‘Student background reading sheet' learners draw a cartoon strip of a carbon atom moving through the ecosystem. Lower ability learners draw the route through the fern, fossil fuel and combustion. Higher ability learners draw the route through the fern, dinosaur, ocean, marine animal shell, chalk cliffs etc. In pairs learners explain their cartoon to each other.
4. Answer the questions in pairs at the end of the worksheet.
Lesson plan covering the stages of the nitrogen cycle. Learners role play being atoms of nitrogen gas moving around the nitrogen cycle dependent on the roll of a die.
After learners have completed the activity, higher level learners can complete the 'Nitrogen cycle activity sheet', looking in more detail at the different types of microorganisms involved at the different stages of the nitrogen cycle.
Lesson plan giving instruction on how learners can plan and carry out a practical to find the effect different factors such as temperature, light and water content have on the decomposition of a piece of carrot.
Learners can work in groups, with each learner in the group testing a different factor or each group in the class may test a different factor. Groups may then present their findings at the end of the topic.
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