4 Ecology and the environment
Start with Concept to understand a topic, then use Question Bank to check what you know.
Your progress
Sign in to see your mastery and mistakes.
(a) The organism in the environment
4.1Ecology terms
Understand the terms population, community, habitat and ecosystem.
4.2Comparing population size
Practical: investigate the population size of an organism in two different areas using quadrats.
4.3BBiodiversity
Understand the term biodiversity.
4.4BQuadrat sampling practical
Practical: investigate the distribution of organisms in their habitats and measure biodiversity using quadrats.
4.5Abiotic and biotic factors
Understand how abiotic and biotic factors affect the population size and distribution of organisms.
(b) Feeding relationships
4.6Trophic levels
Understand the names given to different trophic levels, including producers, primary, secondary and tertiary consumers and decomposers.
4.7Concepts of food chains
Understand the concepts of food chains, food webs, pyramids of number, pyramids of biomass and pyramids of energy transfer.
4.8Food chains and energy transfer
Understand the transfer of substances and energy along a food chain.
4.9Ten percent energy transfer
Understand why only about 10% of energy is transferred from one trophic level to the next.
(c) Cycles within ecosystems
4.10Carbon cycle
Describe the stages in the carbon cycle, including respiration, photosynthesis, decomposition and combustion.
4.11BNitrogen cycle
Describe the stages in the nitrogen cycle, including the roles of nitrogen fixing bacteria, decomposers, nitrifying bacteria and denitrifying bacteria (specific names of bacteria are not required).
(d) Human influences on the environment
4.12Air pollution consequences
Understand the biological consequences of pollution of air by sulfur dioxide and carbon monoxide.
4.13Greenhouse gases
Understand that water vapour, carbon dioxide, nitrous oxide, methane and CFCs are greenhouse gases.
4.14Human sources of greenhouse gases
Understand how human activities contribute to greenhouse gases.
4.15Enhanced greenhouse effect
Understand how an increase in greenhouse gases results in an enhanced greenhouse effect and that this may lead to global warming and its consequences.
4.16Sewage pollution consequences
Understand the biological consequences of pollution of water by sewage.
4.17Eutrophication consequences
Understand the biological consequences of eutrophication caused by leached minerals from fertiliser.
4.18BDeforestation effects
Understand the effects of deforestation, including leaching, soil erosion, disturbance of evapotranspiration and the carbon cycle, and the balance of atmospheric gases.