Autotroph synthesise organic molecules from simple inorganic substances.

i.e.: Photosynthesis. Chemosysnthesis

Heterotrophs obtain organic molecules from other organisms via different feeding mechanisms and different food sources

Species is a group of organisms that can (potentially) interbreed to produce viable, fertile offspring.

• Variation within species might limit mating within the species. Although capable of interbreeding, individuals do not.
  

• Members of the same species might be capable of interbreeding but they do not because of geographic isolation.

• Boundaries of a species gene pool can be unclear, and in some situations different species may be able to interbreed to create hybrids and some hybrids are sterile.

• With ring species, neighbouring populations of a species may be able to interbreed but the two "ends of the chain" cant interbreed.
  
  
  

• Interbreeding capability is unknown for extinct organisms

U2 Members of a species may be reproductively isolated in separate populations.

• Organisms that live in different regions (i.e. different populations) are reproductively isolated and unlikely to interbreed, however are classified as the same species if interbreeding is functionally possible

Obtain materials (i.e. nitrogen, oxygen, ammonia) from abiotic environment.

Consumers are heterotrophs that feed on living or recently killed organisms by ingesion
-herbivores
-carnivores
-Omnivores

Scavengers- a type of consumer that principally feed on dead and decaying carcasses rather than hunting live prey

Saprotrophs
Saprotrophs live on (or in) non-living organic matter, secrete digestive enzymes into it and absorbing the products of digestion
-external digestion aided by enzyme secretion

Detritivores
Detritivores are a type of heterotroph that obtains nutrients from non-living organic sources, such as detritus and humus