Statement I : Chameleon changes its skin colour to match with the colour of the surroundings Statement I : The skin of chameleon emits light of the colour of the surrounding through fluorescence

Statement I is true as chameleons change their skin colour to blend with their surroundings, though this mechanism is also triggered by mood, temperature, and social signals [1]. Statement II is false because the colour change is not caused by fluorescence (the emission of light). Instead, it is a physical process involving structural coloration [3]. Chameleons possess a superficial layer of dermal cells called iridophores containing a lattice of guanine nanocrystals [2]. By actively tuning the spacing between these nanocrystals, the skin reflects different wavelengths of light. Tightly packed crystals reflect shorter wavelengths like blue, while relaxed, wider spacing reflects longer wavelengths like yellow or red [4]. This structural reflection, combined with pigments in chromatophores, creates the visible colour change, rather than the skin emitting light through fluorescence.

Sources

1. [1] Science-Class VII . NCERT(Revised ed 2025) > Chapter 5: Changes Around Us: Physical and Chemical > Exploratory Projects > p. 72
2. [3] https://pmc.ncbi.nlm.nih.gov/articles/PMC4366488/
3. [2] https://www.nature.com/articles/ncomms7368
4. [4] https://www.newscientist.com/lastword/mg24732911-900-how-do-chameleons-change-colour/