The organ which was considered vestigial until recently but is now confirmed to be an endocrine gland is:

$I.$ Sleep-wake cycle,$II.$ Body temperature,$III.$ Pigmentation,$IV.$ Metabolism,$V.$ Defence capability. All of the above-mentioned activities are influenced/regulated by:

The amino acid tryptophan is the precursor for the synthesis of

The pineal gland secretes which hormones?
$I. Serotonin$ $II. ACTH$ $III. MSH$ $IV. PRL$ $V. Melatonin$ $VI. FSH$
The correct option is:

The function of the pineal body is to

Identify the hormone with its correct matching of source and function.