With one gene controlling a trait we have three possible genotypes, AA, Aa and aa and depending on the allelic interactions (dominance or incomplete dominance) we can have two or three phenotypes. As more and more genes control a trait, a greater number of genotypes are possible. The formula that predicts the number of genotypes from the number of genes is 3 to the power n. (n is the number of genes.) The following is the number of genotypes for a selected number (n) of genes which control an arbitrary trait.
Coal-Powered Electric Cars Out-Pollute Fossil Fuels. by. If the energy used to power electric vehicles comes from traditional resources such as burning coal rather than renewable sources, driving battery-powered cars will pollute the air more than cars powered by fossil fuels.
One car in our tests that doesn't rely on fuel at all is the Nissan Leaf, which only runs on electric. However, this money-saving green machine may become useless in a power outage. Plug-in hybrids, such as the Chevrolet Volt, offer the best of both worlds--gas and electric. The Volt's combined range is a modest 325 miles, but the flexibility of energizing based on gasoline or electricity availability gives this car extra storm appeal. Looking at the list below, hybrid and diesel sedans tend to dominate for the long-haul combining excellent fuel economy with respectable tank size.