19.4) Population size Population: is a group of organisms of one species, living and interacting in the same area at the same time. Community: is all of the populations of different species in an ecosystem. Ecosystem: is a unit containing the community of...
19.2) Food chains and food webs Food chain: shows the transfer of energy from one organism to the next, beginning with a producer. Food web: is a network of interconnected food chains. Producer: is an organism that makes it own organic nutrients, usually using...
19.3) Nutrient cycles The carbon cycle: Carbon is an element that occurs in all the compounds which make up living organisms. Plants get their carbon from carbon dioxide in the atmosphere and animals get their carbon from plants. The carbon cycle, therefore, is...
19.1) Energy flow Nearly all living things depend on the Sun to provide energy. This is harnessed by photosynthesising plants and the energy is then passed through food chains. With the exception of atomic energy and tidal power, all the energy released...