Question

When an electron has been excited to a higher energy state, it can then drop back to the original level, re-emitting the light as fluorescence. When chlorophyll is extracted in solution and a bright red or blue light is shown on it, the chlorophyll fluoresces brightly. However, when the chlorophyll is packaged inside chloroplasts and the red or blue light is turned on, there is no fluorescence. This most likely indicates that?

• A. The red and blue light waves are reflected by the chlorophyll membrane
• B. Chlorophyll in solution is a different molecule than chlorophyll in a chloroplast
• C. The excited electrons are transferred to electron acceptors in the chloroplast
• D. The green light must be used to make living cells fluorescence

Answer 1

The correct option is C The excited electrons are transferred to electron acceptors in the chloroplast

Light reaction of the photosynthesis starts from the excitation of chlorophyll by a photon. When a photon of light energy falls on chlorophyll molecule, it gets excited and moves on to a higher level called excited singlet state. The electron gap in the photosystem is further filled by the process of photolysis. The light-dependent reactions begin in photosystem II. When a chlorophyll a molecule within the reaction center of PSII absorbs a photon, an electron in this molecule attains a higher energy level because this state of an electron is very unstable, the electron is transferred from one to another molecule creating a chain of redox reactions, called an electron transport chain (ETC). The electron flow goes from PSII to cytochrome b6f to PSI. In PSI, the electron gets the energy from another photon. The final electron acceptor is NADP. In oxygenic photosynthesis, the first electron donor is water, creating oxygen as a waste product. In anoxygenic photosynthesis, various electron donors are used. So, the correct answer is option C.