TCE Environmental Science exam 2026Exam: Wed 11 Nov · TASC timetable

This is the single most important contrast in this topic. Energy enters as sunlight, passes through organisms once and is lost as heat, so it must be constantly resupplied. Matter is not lost; the same carbon, nitrogen and water atoms are recycled again and again.

A keystone species has a disproportionately large effect on its ecosystem relative to its abundance, so its removal causes major change. The sea otter is a classic global example; in Tasmanian giant kelp forests, sea urchin grazing pressure illustrates how losing predators reshapes an ecosystem.

Carrying capacity is the largest population of a species that an environment can support indefinitely without its resources being permanently degraded.

Eutrophication is the over-enrichment of water with nutrients, especially nitrogen and phosphorus from fertiliser or waste, which triggers excessive algal growth. When the algae die and decompose, oxygen is stripped from the water, killing fish and other aquatic life.

The demographic transition is the shift a population undergoes as a country develops, moving from high birth and death rates, through a phase of rapid growth where deaths fall before births, to low birth and death rates and a stable or shrinking population.

Ecosystem services are the direct and indirect benefits that humans obtain from functioning ecosystems, including the provision of resources, the regulation of natural processes, and cultural and supporting roles.

A point source is pollution discharged from a single identifiable location, such as a pipe or chimney. A non-point source is pollution that enters the environment from many scattered, hard-to-trace origins across a landscape.

Ozone depletion is the thinning of the stratospheric ozone layer caused by human-made chemicals such as CFCs releasing chlorine, which catalytically destroys ozone and lets more ultraviolet radiation reach the surface.

An invasive species is a non-native organism that establishes and spreads in a new environment, causing harm to native species, ecosystems or human interests because local species lack defences against it.

Habitat fragmentation is the breaking up of a continuous habitat into smaller, isolated patches separated by cleared or developed land. It reduces the total area of habitat and increases the proportion of habitat that is near an edge.

The enhanced greenhouse effect is the additional warming caused when human activities increase the concentration of greenhouse gases, trapping more heat than the natural greenhouse effect alone.

Reliability is the consistency of results when a measurement is repeated under the same conditions. Validity is whether the method actually measures what it is intended to measure. Good fieldwork needs both.

Ecologically sustainable development is using, conserving and enhancing the community's resources so that ecological processes are maintained and the total quality of life, now and in the future, can be increased.

A stakeholder is any individual or group with an interest in, or who is affected by, an environmental issue or decision, such as governments, industries, local communities, Aboriginal people, scientists and conservation organisations.

Ecologically sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs, while maintaining ecological processes and biodiversity.