Ecosystems (B4.1) | OCR GCSE Combined Science A (Gateway Science) — Biology — Higher (J250)

Summary Microorganisms play an important role in the continuous cycling of chemicals in ecosystems. Biotic and abiotic factors interact in an ecosystem and have an effect on communities. Living organisms form populations of single species, communities of many species and are part of ecosystems. Living organisms are interdependent and show adaptations to their environment. Feeding relationships reflect the stability of an ecosystem and indicate the flow of biomass through the ecosystem. Underlying knowledge and understanding Learners should be familiar with the idea of a food web and the interrelationships associated with them and that variation allows living things to survive in the same ecosystem. They should also recognise that organisms affect their environment and are affected by it.

Common misconceptions Research has shown that it is easier for a learner to explain the consequences on a food web if the producers are removed for some reason than if the top predators are taken away. It is also better to start off explaining ideas relating to food webs using small simple webs with animals and plants that learners are likely to know e.g. rabbits and foxes. Learners find arrows showing the flow of biomass from one trophic level to another quite challenging and often mistake it for the direction of predation. This makes problems relating to the manipulation of a food web quite difficult for some.

Reference	Mathematical learning outcomes	Maths skills
$BM4.1i$	$Calculate the percentage of mass$

Calculate the percentage of mass

Plot and draw appropriate graphs selecting appropriate scales for the axes

Learning outcomes	To include	Maths	Working scientifically	Practical suggestions
$B4.1a recall that many different materials cycle through the abiotic and biotic components of an ecosystem$	$examples of cycled materials e.g. nitrogen and carbon$
$B4.1b explain the role of microorganisms in the cycling of materials through an ecosystem$	$the role of microorganisms in decomposition$			$Research into the range of ecosystems and examples of micro-organisms that act as decomposers within them. (PAG B1, PAG B2, PAG B3, PAG B5)$
$B4.1c explain the importance of the carbon cycle and the water cycle to living organisms$	$maintaining habitats, fresh water flow of nutrients and the stages of the carbon and water cycles$
$B4.1d describe different levels of organisation in an ecosystem from individual organisms to the whole ecosystem$		$M1c$
$B4.1e explain how abiotic and biotic factors can affect communities$	$temperature, light intensity, moisture level, pH of soil, predators, food$	$M4a, M4c, M3a$	$WS1.3a, WS1.3b, WS1.3e WS1.3h, WS2a, WS2b, WS2c, WS2d$	$Identification of the biotic factors in an ecosystem using sampling techniques. (PAG B2)$
$B4.1f describe the importance of interdependence and competition in a community$	$interdependence relating to predation, mutualism and parasitism$		$WS1.4a$	$Examination of the roots of a leguminous plant e.g. clover to observe the root nodules. (PAG B1) Investigation of the holly leaf miner or the horse-chestnut leaf miner (Cameraria ohridella). (PAG B1, PAG B2)$

B4.1a recall that many different materials cycle through the abiotic and biotic components of an ecosystem

examples of cycled materials e.g. nitrogen and carbon

B4.1b explain the role of microorganisms in the cycling of materials through an ecosystem

the role of microorganisms in decomposition

Research into the range of ecosystems and examples of micro-organisms that act as decomposers within them. (PAG B1, PAG B2, PAG B3, PAG B5)

B4.1c explain the importance of the carbon cycle and the water cycle to living organisms

maintaining habitats, fresh water flow of nutrients and the stages of the carbon and water cycles

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

temperature, light intensity, moisture level, pH of soil, predators, food

WS1.3a, WS1.3b, WS1.3e WS1.3h, WS2a, WS2b, WS2c, WS2d

Identification of the biotic factors in an ecosystem using sampling techniques. (PAG B2)

B4.1f describe the importance of interdependence and competition in a community

interdependence relating to predation, mutualism and parasitism

Examination of the roots of a leguminous plant e.g. clover to observe the root nodules. (PAG B1) Investigation of the holly leaf miner or the horse-chestnut leaf miner (Cameraria ohridella). (PAG B1, PAG B2)

Ecosystems

Next Steps

Learning Objectives