A transmitted 8-bit byte is 01010101. The Parity bit is?

It's the most significant bit. So in this case it looks like you have odd parity (assuming the parity bit is correct)

PS. Yes I'm purposefully avoiding answering the question directly, "most significant bit" should be plenty to tell you what it is.
This should have been obvious, if it were the least significant bit it would be much more obfuscating to the information, the most significant bit is the logical place to put it.

A transmitted 8-bit byte is 01010101. The Parity bit is??

Sounds like this is a homework assignment along with your other two posts regarding 10 computers and switches and hubs.