Sex Chromosomes. Sex chromosomes are particular chromosomes that are involved in determining the sex of an organism. In the cells of humans and many other organisms the sex chromosomes consist of a pair of chromosomes called the X and Y chromosomes. The X and Y chromosomes were first discovered in beetles by Nettie Stevens in 1906.
What makes up household dust: 1  Dead skin cells. 2  Live dust mites. 3  Dead dust mites and dust mite feces.  Pollen and 1  allergens. Combustion byproducts (smoke)  Clothing 1  fibers. Pesticide residue.
Elements of a Dust Explosion. For a combustible dust explosion to occur, the necessary elements for a fire must be present (âfire triangleâ). The ele-. ments are: a fuel source (combustible dust); a heat or ignition source (e.g., electrostatic discharge, an electric current arc, a glowing ember, a hot surface, welding.