Final answer:
Steroid hormones are synthesized on demand from cholesterol precursors and are not stored like other hormone types, making them the correct answer to the question.
Step-by-step explanation:
The hormone that is synthesized on demand from precursors, as opposed to being stored for later release, is steroid hormones. Unlike peptide hormones, catecholamines, and thyroid hormones.
Which are stored in secretory vesicles, steroid hormones are synthesized when they are needed from cholesterol, which serves as their precursor. Since steroid hormones are lipid-soluble, they can cross cell membranes easily and don't require storage within cells in vesicles.
Catecholamines like epinephrine and norepinephrine are synthesized in the medulla of the adrenal glands and are derived from the amino acid tyrosine. They play a role in the fight-or-flight response.
On the other hand, peptide hormones, which include molecules like antidiuretic hormone and oxytocin, are formed as pre-hormones and stored prior to release. Lastly, thyroid hormones are stored within the thyroid gland before they are released into the bloodstream.