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.
Soils are a composition of mineral particles 45% , organic matter 5% , air 25% , and water 25% . Mineral Particles: Mineral particles are the largest ingredient and make up approx 45% of soils. They are the original rock that got broken down by weathering and erosion to form the basis of soil.oil is composed of both organic and inorganic matter, and it is essential for life on earth to exist. The soil type that i have studied is brown earths. Brown earths are the most common soil type in Ireland and are very fertile.