Biodiversity The variety of species in a natural environment. Diversify To increase the variety. Ecosystem A community of organisms and their non-living environment. Externality The indirect effect of an activity, such as pollution. GNP Gross National Product, the total value of all the goods and services produced by a country in a year. It is often measured 'per capita' or per person, to make an average. Infant Mortality The number of babies out of every thousand born that die before the age of one. LEDC Stands for Less Economically Developed Country. Multiplier Effect The knock-on effect of an activity (such as jobs created in other activities) Quota A restriction in the quantity of a particular good or service that a country is allowed to sell/trade. Relief Rainfall Rainfall caused by moist air being forced to rise over higher ground where it cools and condenses. Sustainable "Development which meets the needs of the present without compromising the ability of future generations to meet their own needs". The Bruntland Commission's definition. Tariff A duty (tax) on goods imported into a country.