Frepresents the gene for brown coat color and f represents the gene for white coat color. in the cross ff x ff all the offspring have a brown coat. which genetic principle is illustrated by this cross?

It represents the dominance.
The dominance occurs when an allele (dominant) that is expressed in an organism’s phenotype, masks the effect of the recessive allele that is also present. In this case allele for brown coat color (F) is dominant to the allele for white coat color (f). When these two alleles are together (genotype is Ff) the brown color will be expressed as a phenotype.

To wear the full equipment.

Air enters through the nose (and sometimes the mouth), moves through the nasal cavity, the  pharynx, the  larynx, enters the  trachea, moves through the  bronchi  andbronchioles  till the alveoli.