A.) Convention currents in Earth's mantle
The seven levels of classification are Kingdom, Phylum, Class, Order, Family, Genus, and Species.
Humans obtain nitrogen by eating other organisms.
According to Charles Darwin's theory of Evolution by natural selection, organisms that possess heritable traits that enable them to better adapt to their environment compared with other members of their species will be more likely to survive, reproduce, and pass more of their genes on to the next generation.
(n.d.). Retrieved from http://www.nas.edu/evolution/Definitions.html
One word answer:Adaptation: