Q. Which one of the following pairs of chemical substances is correctly categorised?
A) Calcitonin and thymosin – Thyroid hormones
B) Pepsin and prolactin – Two digestive enzymes secreted in stomach
C) Troponin and myosin – Complex proteins in striated muscles
D) Secretin and rhodopsin – Polypeptide hormones
Explanation
[Solution from source] Troponin and myosin are both proteins of the contractile machinery of striated muscle. Thymosin comes from the thymus, not the thyroid; prolactin is a pituitary hormone; and rhodopsin is a visual pigment, not a hormone. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.