• Loss of Matter and Energy - At each trophic level along a food chain, there is always a 'loss' of matter and energy in the forms of waste (e.g. carbon dioxide, faeces), and heat and kinetic energy (e.g. constant body temperature of mammals, the energy used to move). Up to 90% of matter and energy can be 'lost' at each level.
• Biomass - the total dry weight of the organisms in a trophic level
• Biomass Pyramid - a diagram showing the biomass at each trophic level of a food chain

BIOLOGICAL MAGNIFICATION

• Some chemicals that are taken in from the environment by plants, or consumed by animals, cannot be excreted by organisms. They accumulate in the body by the organisms, sometimes up to toxic levels. The more organisms there are in a food chain, the greater is the accumulation in the higher order consumers. Such chemicals include the pesticide DDT, and heavy metals such as mercury.

BIOLOGICAL CONTROL

• Pests - Pests may be plant or animal. They usually are introduced from overseas. Because of both their ability to survive and reproduce successfully in the Australian habitat, and their lack of predators or parasites, they reach pest population numbers, competing with the native flora and fauna.
• Biological Control of the populations of pest plants and animals is accomplished by non- chemical means involving predation, parasitism, or interruption to reproduction. Biological control is usually specific to a particular pest organism.
• Successful Biological Control Experiment Examples

1. Prickly Pear Cactus - This introduced species was a pest throughout cattle farms in Queensland. The introduction of the Cactoblastis Moth reduced its numbers through consumption.
2. European Rabbit - Rabbits arrived in Australia in 1788 and reproduced rapidly. The Myxoma Virus was developed in the 1900's to spread by direct contact and cause death.

• Unsuccessful Biological Control Experiment Examples