Section 4: Ecology and the environment

a) The organism in the environment
b) Feeding relationships
c) Cycles within ecosystems
d) Human influences on the environment

a) The organism in the environment

4.1 understand the terms population, community, habitat and ecosystem

4.2 recall the use of quadrats to estimate the population size of an organism in two different areas

4.3 describe the use of quadrats as a technique for sampling the distribution of organisms in their habitats.

b) Feeding relationships

4.4 recall the names given to different trophic levels to include producers, primary, secondary and tertiary consumers and decomposers

4.5 understand the concepts of food chains, food webs, pyramids of number, pyramids of biomass and pyramids of energy transfer

4.6 understand the transfer of substances and of energy along a food chain

4.7 explain why only about 10% of energy is transferred from one trophic level to the next.

c) Cycles within ecosystems

4.8 describe the stages in the water cycle, including evaporation, transpiration,
condensation and precipitation

4.9 describe the stages in the carbon cycle, including respiration, photosynthesis,
decomposition and combustion

4.10 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

4.11 understand the biological consequences of pollution of air by sulfur dioxide and by carbon
Monoxide

4.12 recall that water vapour, carbon dioxide, nitrous oxide, methane and CFCs are greenhouse
Gases

4.13 understand how human activities contribute to greenhouse gases

4.14 understand how an increase in greenhouse gases results in an enhanced greenhouse effect
and that this may lead to global warming and its consequences

4.15 understand the biological consequences of pollution of water by sewage including increases in the number of microorganisms causing depletion of oxygen

4.16 understand that eutrophication can result from leached minerals from fertilizer

4.17 understand the effects of deforestation, including leaching, soil erosion, disturbance of the water cycle and of the balance in atmospheric oxygen and carbon dioxide.

Credit:

All the notes for IGCSE Biology are written by Michelle Lim from http://www.askmichellebiology.blogspot.com/