Beta decay is a consequence of the weak force, which is characterized by relatively lengthy decay times. Nucleons are composed of up or down quarks, and the weak force allows a quark to change type by the exchange of a W boson and the creation of an electron/antineutrino or positron/neutrino pair.
Most procaryotes contain some sort of a polysaccharide layer outside of the cell wall polymer. In a general sense, this layer is called a capsule. A true capsule is a discrete detectable layer of polysaccharides deposited outside the cell wall.
A variety of organisms have cell walls. Plant cell walls are made of mostly of cellulose, hemicellulose, and pectin. There compounds make a rigid cell wall that gives the plant structure to support itself. Fungi and other organisms like diatoms have cell walls made of different compounds such as chitin and silica.