What is free nitrogen? Nitrogen gas is called "free" nitrogen, meaning it is not combined with other kinds of atoms. Most organisms can use nitrogen only once it has been "fixed," or combined with other elements to form nitrogen-containing compounds.

The graph shows the amount of global warming happening in different ecosystems. which populations of organisms will likely decline the most as a result of climate change, and why? a.coral reefs because of the loss of the symbiotic algae living within their bodies b.penguin populations because the fish they eat will move into warmer waters c.mountain-dwelling birds because rising sea levels will relocate their food sources d.large cats in the rainforest because of decreased habitat loss for their prey