Explain how hydrogen fuel cells work, and why they provide a healthy, clean way to produce heat and electricity. (Site 1).

As there are no moving parts, fuel cells operate silently and with extremely high reliability. Due to their chemistry, fuel cells are very clean. Fuel cells that use pure hydrogen fuel are completely carbon-free, with their only byproducts being electricity, heat, and water.

an organism's phenotype is the  form of a trait  that it  displays. for  flowercolor, a pea  plant  can  display  a phenotype of purple or white flowers. an organism's  genotype  is the alleles of a gene it contains. based on his data, mendel concluded that a phenotype can be  determined  by more than one  genotype.