The linear mass density can then be understood as the derivative of the mass function with respect to the one dimension of the rod (the position along its length =) The SI unit of linear mass density is the kilogram per meter (kg/m). Linear density of fibers and yarns can be measured by many methods.
An Arabidopsis thaliana chlorophyll(ide) a oxygenase gene (cao), which is responsible for chlorophyll b synthesis from chlorophyll a, was introduced and expressed in a photosystem I-less strain of the cyanobacterium Synechocystis sp.
The light absorption processes associated with photosynthesis take place in large protein complexes known as photosystems. The one known as Photosystem II contains the same kind of chlorophyll a as Photosystem I but in a different protein environment with an absorption peak at 680 nm. (It is designated P680).