[Campbell Biology P.244] Why does a chlorophyll solution fluoresce under UV light, while a l... | Practice Question

Why does a chlorophyll solution fluoresce under UV light, while a leaf with the same chlorophyll concentration does not exhibit significant fluorescence when exposed to the same UV light?

  • A: In the leaf, the energy from excited chlorophyll is efficiently transferred to other pigments and reaction centers for photosynthesis, rather than being released as fluorescence.
  • B: The leaf's epidermal layers filter out most UV light, preventing chlorophyll excitation.
  • C: Chlorophyll in a leaf undergoes a different chemical modification that prevents it from fluorescing.
  • D: The absorbed UV energy in a leaf is immediately converted into heat, leaving no energy for fluorescence.

Explanation

In isolated chlorophyll solutions, excited electrons typically release excess energy as heat and fluorescence light . However, in the native environment of a leaf within photosystems , the energy of the excited chlorophyll is efficiently transferred to other pigment molecules and ultimately to the reaction center for use in photosynthesis. This rapid and efficient energy transfer prevents the energy from being lost as fluorescence.