What is meant by photo oxidation?
Photo-oxidation is the degradation of a polymer surface in the presence of oxygen or ozone. The effect is facilitated by radiant energy such as UV or artificial light. This process is the most significant factor in weathering of polymers. Photo-oxidation is a chemical change that reduces the polymer’s molecular weight.
What is photo oxidation in plants?
The light‐dependent generation of active oxygen species is termed photooxidative stress. This can occur in two ways: (1) the donation of energy or electrons directly to oxygen as a result of photosynthetic activity; (2) exposure of tissues to ultraviolet irradiation.
What is Photooxidation reaction?
Photo-oxidation is a chain process incorporating a large number of chemical reactions which are subsequent to the outcome of the primary event—absorption of a photon, which induces breakdown to free-radical products.
What is photo oxidation of water?
PHOTO OXIDATION OF WATER:- • The PS-II reaction centre (P680) by transferring electron to primary acceptor becomes oxidised. • The overall process is called photo-oxidation of water. It requires the presence of Mn++, Ca+ and Cl- , a water oxidising enzyme and an unknown substance Z.
What is photo oxidation of chlorophyll?
It can be seen that, during photo-oxidation, the specific activities, both of chlorophyll a and chlorophyll by increase considerably, whilst the pigments are photo-decomposed. The increase occurs earlier for chlorophyll b. than for chlorophyll a; it is also more pronounced in chlorophyll b than in chlorophyll a.
What is the definition of oxidation?
Oxidation is loss of electrons (OIL RIG). That means that an oxidising agent takes electrons from that other substance. So an oxidising agent must gain electrons.
What is oxidative degradation?
Oxidative degradation involves the disintegration of macromolecules by the action of oxygen on the substrate (oxidation). Free radicals are formed which react with oxygen-producing oxy- and peroxy-radicals. … It takes place as a result of the simultaneous interaction of oxygen with the polymer and high temperature.
Which pigment can protect chlorophyll from Photooxidative damage?
What are light reactions?
Definition. noun. The series of biochemical reactions in photosynthesis that require light energy that is captured by light-absorbing pigments (such as chlorophyll) to be converted into chemical energy in the form of ATP and NADPH.
What is photoreduction reaction?
Photochemical Reaction Types 1. Photoreduction • Photoreduction is defined as the addition of one or more electrons to a photoexcited species or the photochemical hydrogenation of a substance. … This can also refer to the reaction of a species with molecular oxygen as a result of light irradiation.