The energy of a photon in electronvolts is 1240 divided by the wavelength in nanometres…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
The energy of a photon in electronvolts is divided by the wavelength in nanometres. (a) Find the energy of a photon of , which best excites P680. (b) Find the energy of a photon of , which best excites P700. (c) Which photon carries more energy?
Need a reminder? The key ideaShow
Photosystems: PS I and PS II, named in the order of discovery. Each has an antenna (the light harvesting complex, hundreds of pigment molecules bound to proteins) and one chlorophyll a reaction centre: P680 in PS II and P700 in PS I. Water is split at PS II in the lumen: . Grana have both photosystems. Stroma lamellae have PS I but no PS II and no NADP reductase. Photon energy in eV with in nm.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. At 680 nm. .
Step 2. At 700 nm. .
Step 3. Compare. is more than , so the photon of carries more energy.
Check. The wavelengths differ by only a few percent, so the energies are close.
Answer: (a) ; (b) ; (c) the photon.
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