U5 Transfers of Energy & Matter

• What can an ecosystem be defined as?

  A group of organisms interacting with each other and with the non-living parts of the environment
• There are both biotic components and abiotic components within an ecosystem
• Biotic factors are concerned with the living organisms in the environment
• Abiotic factors are concerned with the non-living part of the environment
• Ecosystems vary in complexity:

  • A desert is a relatively simple ecosystem
  • A tropical rainforest is a very complex ecosystem
• In an ocean, the abiotic components of the ecosystem include the salinity, pH, temperature, light intensity, and mineral availability
• The abiotic components of the ecosystem influence the community of organisms, e.g. by providing habitat, nutrients and other resources organisms need in order to survive and reproduce
• Ecosystems are open systems, meaning that both energy and matter can enter and exit the system
• Ecosystems are open systems, meaning that both energy and matter can enter and exit the system
• Energy can also enter an ecosystem stored in the tissues of any organisms that migrate into the system
• When energy is stored in the molecules of an organism and that individual leaves the ecosystem, that stored energy is removed
• Matter enters an ecosystem when an organism arrives, in the form of all of the molecules of its cells and tissues, e.g. when a bird migrates into an ecosystem
• Matter is removed when an organism leaves an ecosystem, e.g. dead plant matter could be washed away by the waves on a beach and carried to a new ecosystem
• Open systems are different to closed systems
• In a closed system matter can only be recycled within the system and cannot enter or leave
• In a closed ecosystem energy can enter and leave
• Earth is an example of a closed system; energy enters and leaves but matter is recycled
• The sun is the initial source of energy for most food chains
• Light energy from the sun is converted by producers into chemical energy stored in the tissues of plants during the process of photosynthesis
• Chemical energy stored in the tissues of plants passes to primary consumers when they ingest plants, and on to secondary consumers when the primary consumers are themselves ingested
• Food chains located in deep sea volcanic vents and underground caves where no light can penetrate; these rely on bacteria gaining energy from chemical processes
• All reactions lose heat to the environment