#7.2.1
Levels of organisation
Students should understand that photosynthetic organisms are the producers of biomass for life on Earth.
Feeding relationships within a community can be represented by food chains. All food chains begin with a producer which synthesises molecules. This is usually a green plant or alga which makes glucose by photosynthesis.
A range of experimental methods using transects and quadrats are used by ecologists to determine the distribution and abundance of species in an ecosystem.
#7.2.2
How materials are cycled
Students should:
- recall that many different materials cycle through the abiotic and biotic components of an ecosystem
- explain the importance of the carbon and water cycles to living organisms.
All materials in the living world are recycled to provide the building blocks for future organisms.
The carbon cycle returns carbon from organisms to the atmosphere as carbon dioxide to be used by plants in photosynthesis.
The water cycle provides fresh water for plants and animals on land before draining into the seas. Water is continuously evaporated and precipitated.
Students are not expected to study the nitrogen cycle.
Students should be able to explain the role of microorganisms in cycling materials through an ecosystem by returning carbon to the atmosphere as carbon dioxide and mineral ions to the soil.
#7.2.3
Decomposition
Students should be able to explain how temperature, water and availability of oxygen affect the rate of decay of biological material.
#7.2.4
Impact of environmental change
Students should be able to evaluate the impact of environmental changes on the distribution of species in an ecosystem given appropriate information.
Environmental changes affect the distribution of species in an ecosystem. These changes include:
- temperature
- availability of water
- composition of atmospheric gases.
The changes may be seasonal, geographic or caused by human interaction.