- The endostyle is found in protochordates (like Amphioxus). It secretes mucus to trap food particles.
- During evolution, the endostyle was modified into the thyroid gland in vertebrates.
- Atrium refers to a chamber in the heart.
- Pharynx is part of the digestive/respiratory system but not directly the thyroid precursor.
- Test refers to a protective covering (in tunicates), not endocrine-related.
Write one difference between dominant and recessive trait.