Questions: Multiple Choice Question Which combination of sex chromosomes in an embryo leads to embryonic death? XO XYY XXX OY

The answer is the last one (OY): OY.

Explanation for each option:

1. XO: This combination results in Turner syndrome, a condition where a female is born with only one X chromosome. Individuals with Turner syndrome can survive, although they may have various developmental and medical challenges.

2. $X Y Y$: This combination is not typically viable in humans. However, if it were to occur, it would likely result in a non-viable embryo due to the presence of an extra Y chromosome, which disrupts normal development. However, this is not a standard notation for a known condition.

3. XXX: This combination results in Triple X syndrome, where a female has an extra X chromosome. Individuals with this condition can survive and may lead relatively normal lives, although they might experience some developmental and learning difficulties.

4. OY: This combination leads to embryonic death because the presence of a Y chromosome without an X chromosome is not viable. The X chromosome carries essential genes necessary for survival, and without it, the embryo cannot develop properly.

In summary, the combination of sex chromosomes that leads to embryonic death is OY.