Multiple choice

The function of water in photosynthesis is to ______.

  1. convert sunlight into chemical energy

  2. combine with CO2

  3. supply electrons in the light-dependent reactions

  4. absorb light energy
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Light strikes photosystem-2 by exciting the electrons. The electron comes from a water molecule that has been split into hydrogen and oxygen. The excited electrons then travel down a short electron transport chain, and while doing so, they pump H+ into the inner thylakoid space across the thylakoid membrane from the stroma. The electrons are then passed, at the end of the transport chain, to photosystem 1, where they are re-excited by light.

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