The question lists four hormones and asks which ones are peptide based, meaning built from chains of amino acids, rather than steroid based, meaning derived from cholesterol. Go through each one individually.
- (i) Estrogen: Estrogen is a steroid hormone, built on the four fused ring structure that comes from cholesterol. It is not a peptide.
- (ii) Insulin: Insulin is a well known protein hormone made of two polypeptide chains linked by disulfide bonds. It is a clear example of a peptide hormone.
- (iii) Endorphin: Endorphins are short chains of amino acids that act on opioid receptors in the nervous system. Being built from amino acid chains makes them peptide based as well.
- (iv) Androgen: Androgens, like testosterone, are steroid hormones derived from the cholesterol backbone, the same family as estrogen, not from amino acids.
So among the four, insulin and endorphin are the amino acid chain based, peptide hormones, while estrogen and androgen both belong to the steroid family instead.
Let's summarize:
- Peptide hormones are built from amino acid chains: insulin and endorphin fall in this group.
- Steroid hormones are built from a cholesterol derived ring system: estrogen and androgen fall in this group.
The peptide based hormones are (ii) Insulin and (iii) Endorphin.