Answer: Bacteria will use the oxidised form of sulphur. Among all the forms of sulphur molecule such as sulphate which is the more oxidised form and also the other forms like thiosulphate,elemental sulphur, sulphite, hyposulphite can be used as an electron acceptor. As the coupling of these organic compounds occur, these sulfur bacterias obtain energy from the subsequent oxidation and then reduction of sulfur forms from sulphate to sulphide which is then released in the environment.
Molecular clocks use rates of mutation to measure evolutionary time.Mutations add up at a fairly constant rate in the DNA of species that evolved from a common ancestor. The more mutations that happened in each lineage, the greater is the differences between these lineages.