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.
1 â. The nucleus is the relatively solid and stable centrally located part, mostly formed of ice and gas with a small amount of dust and other solids like hydrocarbons. 2  The coma is a dense atmosphere surrounding the nucleus, made of a cloud of water, carbon dioxide and other neutral gases as well as dust grains. The dust tail is the most prominent part of a comet: it can be up to 10 million km long, composed of smoke-sized dust particles driven off the nucleus by escaping gases;