When a molecule absorbs a photon, it is said to be excited, or at a higher‑energy state. The excited molecule can return to its ground state when the absorbed energy is dissipated, a process that can occur by several mechanisms. Each phrase describes a mechanism by which the excited molecule releases its energy and returns to its ground state. Determine whether each phrase describes heat, fluorescence, exciton transfer (resonance energy transfer), or photooxidation.
1. The energy that has been converted to a potentially unusable form is lost as .
2. An excited molecule is oxidized and an acceptor molecule is reduced during
3. Absorbed light given off as a lower-energy photon is
4. Absorbed energy may be passed on to another molecule in a process called

1) Heat 2) Photooxidation 3) Fluorescence 4) Excitation transfer

Explanation:

1) The potentially unusable form of energy is known as heat. It is produced by various mechanism such as friction.

2) Photoxidation means the oxidation due to light as chlorophyll a release electron after absorbing the photon. This electron is captured by other molecule so energy is transferred from one molecule to other. Photoxidation also cause increase in oxidative stress (increased production of radicles specifically reactive oxygen species) in body.

3) The process in which a molecule emits the abosrbed energy in the form of light is known as fluorescence. Normally the emitted photon is of greater wavelength (less energy) than the absorbed photon.

4) The optical process in which excess energy of a donor excited molecule is transferred to acceptor molecule is known as Excitation transfer or resonance energy transfer.