Photosynthesis is the transformation of light energy to chemical energy and is mediated by light-harvesting complexes (LHCs). The LHCs present in plants and some bacteria are composed of chromophores, which upon photon absorption are excited from a ground state to an electronic excited state. The energy from the excitation travels amongst the chromophores to the reaction centre where charge separation is initiated with efficiencies between 84% and 90%. This efficiency represents the fraction of the donor chromophores de-excited via energy transfer to the acceptor chromophores. The energy transfer occurs via FRET. Energy transfer is affected by the distance between the chromophores, the spectral overlap between the fluorescence emission of the donor chromophore and the absorption spectrum of the acceptor chromophore, the lifetime of the excited state, and the relative geometric structure of the transition dipole moments of the chromophores. For natural photosynthetic systems, there has been evidence of quantum coherence playing an essential role in explaining the observed efficiencies in energy transfer. Quantum coherence occurs due to strong coupling between chromophores leading to a superposition of excited states.