photorespiration protects plant from photooxidation and photoinhibition.

John Homer has written:

'A brief sketch of the present state of the province of Nova-Scotia' -- subject(s): Commerce, Economic conditions

'Primary processes in the photooxidation of polyolefins'

It has been found that milk contains chlorophyllic compounds in very low concentrations. Not exactly chlorophyll a or b, but probably breakdown products from these. Milk also contains porphyrins such as protoporphyrin and hematoporphyrins. All these compounds contribute to the photooxidation in milk since they are very light sensitive.

The yellow color on the newspaper is evidence of oxidation and chemical breakdown of the paper fibers due to exposure to sunlight. This process is known as photooxidation and it causes the paper to lose its brightness and become yellow over time.

chemicals normally acids and bases change their chemical nature due to bacteial growth after a certain period of time for example 0.01,0.1,1m Hcl expired after 6months normaly,iron salts expecially ferros salts are converted into ferric upon oxidation(photooxidation) Fe+2 ----> Fe+3 Cu+1-----> Cu+2 most of the chemicals due to hygroscopic or anhydrous nature change by absorbing moisture from air,like NaOH and anhydrous salts e-g CaCl2