GCSE Biology Specification

OCR A J247

Section B4.1: Ecosystems

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#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

#B4.1c

explain the importance of the carbon cycle and the water cycle to living organisms

maintaining habitats, fresh water flow of nutrients

#B4.1d

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

the terms aerobic and anaerobic

#B4.1e

describe different levels of organisation in an ecosystem from individual organisms to the whole ecosystem

#B4.1f

explain how abiotic and biotic factors can affect communities

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

#B4.1g

describe the importance of interdependence and competition in a community

interdependence relating to predation, mutualism and parasitism

#B4.1h

describe the differences between the trophic levels of organisms within an ecosystem

use of the terms producer and consumer

#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

#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