A NATO official, speaking on condition of anonymity, pointed out that after the attacks NATO sent AWACS planes to patrol American skies and deployed a third of the troops in Afghanistan for more than a decade; more than 1,000 soldiers from non-U.S. NATO allies and partners were killed there, the official pointed out.
Cells in the human body have 46 chromosomes, including 22 pairs of autosomes and one pair of sex chromosomes (XX in females, XY in males). Because there are two sets of chromosomes, one from each parent, the cells are considered diploid.
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.