Ecosystems (B4.1) | OCR GCSE Biology A (Gateway Science) — Higher (J247)

B4.1 Ecosystems

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	Mathematical skills
$BM4.1i ☑$	$calculate rate changes in the decay of biological material$

Learning outcomes	To include	Maths	Working scientifically	Practical suggestions
$B4.1a recall that many different materials cycle through the abiotic and biotic components of an ecosystem$	$examples of cycled materials e.g. nitrogen and carbon$
$B4.1b explain the role of microorganisms in the cycling of materials through an ecosystem$	$the role of microorganisms in decomposition$			$Research into the range of ecosystems and examples of micro-organisms that act as decomposers within them. (PAG B1, PAG B3, PAG B4, PAG B7)$
$B4.1c explain the importance of the carbon cycle and the water cycle to living organisms$	$maintaining habitats, fresh water, flow of nutrients and the stages of the carbon and water cycles$
$B4.1d explain the effect of factors such ☑ as temperature, water content, and oxygen availability on rate of decomposition$	$the terms aerobic and anaerobic$	$M1c, M2c, M4a, M4c$	$WS1.1b, WS1.1h, WS1.2b, WS1.2c, WS1.2e, WS1.3a, WS1.3b, WS1.3c, WS1.3d, WS1.3e, WS1.3f, WS1.3g, WS2a, WS2b, WS2c, WS2d$	$Investigation of the most favourable conditions for composting. (PAG B1, PAG B3, PAG B4, PAG B7)$
$B4.1e describe different levels of organisation in an ecosystem from individual organisms to the whole ecosystem$		$M1c$
$B4.1f explain how abiotic and biotic factors can affect communities$	$temperature, light intensity, moisture level, pH of soil, predators, food$	$M3a, M4a, M4c$	$WS1.3a, WS1.3b, WS1.3e WS1.3h, WS2a, WS2b, WS2c, WS2d$	$Identification of the biotic factors in an ecosystem using sampling techniques. (PAG B3)$
$B4.1g describe the importance of interdependence and competition in a community$	$interdependence relating to predation, mutualism and parasitism$		$WS1.4a, WS2a, WS2b, WS2c, WS2d$	$Examination of the roots of a leguminous plant e.g. clover to observe the root nodules. (PAG B1) Investigation of the holly leaf miner or the horse-chestnut leaf miner (Cameraria ohridella) (PAG B1, PAG B3)$
$B4.1h describe the differences ☑ between the trophic levels of organisms within an ecosystem$	$use of the terms producer and consumer$			$Investigation of the trophic levels within a children’s story (e.g. The Gruffalo)$
$B4.1i describe pyramids of biomass ☑ and explain, with examples, how biomass is lost between the different trophic levels$	$loss of biomass related to egestion, excretion, respiration$	$M1c, M4a$	$WS1.3c, WS1.3e$	$Discussion of the best food source for humans (e.g. ‘wheat vs. meat’) Production of ecological pyramids.$
$B4.1j calculate the efficiency of ☑ biomass transfers between trophic levels and explain how this affects the number of trophic levels in a food chain$		$M1c$		$Calculation of the biomass transfers using real data.$

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 B3, PAG B4, PAG B7)

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 explain the effect of factors such ☑ as temperature, water content, and oxygen availability on rate of decomposition

the terms aerobic and anaerobic

M1c, M2c, M4a, M4c

WS1.1b, WS1.1h, WS1.2b, WS1.2c, WS1.2e, WS1.3a, WS1.3b, WS1.3c, WS1.3d, WS1.3e, WS1.3f, WS1.3g, WS2a, WS2b, WS2c, WS2d

Investigation of the most favourable conditions for composting. (PAG B1, PAG B3, PAG B4, PAG B7)

B4.1e describe different levels of organisation in an ecosystem from individual organisms to the whole ecosystem

M1c

B4.1f explain how abiotic and biotic factors can affect communities

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

M3a, M4a, M4c

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

Identification of the biotic factors in an ecosystem using sampling techniques. (PAG B3)

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

interdependence relating to predation, mutualism and parasitism

WS1.4a, WS2a, WS2b, WS2c, WS2d

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 B3)

B4.1h describe the differences ☑ between the trophic levels of organisms within an ecosystem

use of the terms producer and consumer

Investigation of the trophic levels within a children’s story (e.g. The Gruffalo)

B4.1i describe pyramids of biomass ☑ and explain, with examples, how biomass is lost between the different trophic levels

loss of biomass related to egestion, excretion, respiration

M1c, M4a

WS1.3c, WS1.3e

Discussion of the best food source for humans (e.g. ‘wheat vs. meat’) Production of ecological pyramids.

B4.1j calculate the efficiency of ☑ biomass transfers between trophic levels and explain how this affects the number of trophic levels in a food chain

M1c

Calculation of the biomass transfers using real data.

Ecosystems

Next Steps

Learning Objectives