Final answer:
The absence of an X chromosome, as in the hypothetical YO configuration, is lethal because the X chromosome carries genes critical for embryonic development. Females use a process called X inactivation to balance the dosage of X-linked genes, but at least one functional X chromosome is necessary for survival.
Step-by-step explanation:
The condition of having no X chromosomes, for example YO, is lethal in humans. Without at least one X chromosome, an embryo cannot develop properly because the X chromosome carries essential genes for development. In typical female development, cells compensate for having two X chromosomes through a process called X inactivation. This involves deactivating one X chromosome in each cell, which becomes a Barr body, ensuring that females express only one set of X-linked genes, similar to males who have only one X chromosome. However, in the absence of an X chromosome entirely, the individual will not survive. This is in contrast to other chromosomal abnormalities, such as Turner syndrome (XO), where the presence of one X allows development but with various physical and reproductive issues.
In humans, the condition of having no X chromosomes, such as YO, is indeed lethal. This is because X chromosomes play a crucial role in the development and functioning of the body. X chromosomes carry essential genes that are involved in various physiological processes. If an individual is missing X chromosomes, they will not develop properly and will not survive.