C, because alleles are alternative forms of a gene that arise from mutation.
Nitrogen is special because it is necessary for growth and reproduction. It's needed for plants and animals to survive. The main function for the atmosphere i believe is to give oxygen and nitrogen.
Translation proceeds in three phases: Initiation: The ribosome assembles around the target mRNA. The first tRNA is attached at the start codon. Elongation: The tRNA transfers an amino acid to the tRNA corresponding to the next codon.
