X Chromosome
Human and most mammal male cells have one X, and a Y chromosome. Birds also have sex chromosomes, but they act in completely the opposite way. Male birds have X and Y chromosomes, and females have a single Y chromosome.
Human and most mammal male cells have one X, and a Y chromosome. Birds also have sex chromosomes, but they act in completely the opposite way. Male birds have X and Y chromosomes, and females have a single Y chromosome.