If a hormone does NOT directly affect cellular activities it

If a hormone does NOT directly affect cellular activities it is most likely a steroid hormone peptide hormone thyroid hormone transcription factor

Solution

Hi,

To go by logic of \"directly affect cellular activities\" the peptide hormones is the answer. Because all other hormones are released into target cell or tissue type, enter the cell membrane and cause seondary messenger mediated signal cascasde.

But the peptide hormones are first synthesized as prohormones, which have to be first activated often by cleavage, either before or after they are secreted. Then in active form they binds to the taget site or rceptor, then eliciting the reaction.

Hence it is Peptide hormones.