Which organisms produce about half of the oxygen on earth answers?

Deer cave cannot support photosynthesis is as not enough sunlight is present. in spite of this, it still has a complex food chain. what is the energy foundation of this food chain?

What causes darkening of the skin as melanin production increases

Zoo geographic regions are characterized by the presence of specific groups of animals these regions are determined by the taxonomic or phylogenetic relationships of animals. the map shows the zoogeographic regions proposed by the naturalist alfred russel wallace in 1876. the similarities of organisms in which two areas numbered above provide the best evidence for common ancestry between the organisms in both locations ?