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​The following statements refer to photosystem structure and function involved in the light-dependent reaction of photosynthesis:​​A. The antenna or l
Question

The following statements refer to photosystem structure and function involved in the light-dependent reaction of photosynthesis:

A. The antenna or light harvesting complex absorbs light energy and transfers it to the reaction centre.
B. The first electron is released from P680 and transferred to QA to produce a semiquinone Qₐ⁻
C. D1, a protein subunit of the plant PSII core complex, is encoded by gene psbD

Which one of the following combinations of statements is INCORRECT?​​

A.

A and B

B.

B and C

C.

A and C

D.

Only C

Correct option is B

Explanation-

Statement A: "The antenna or light harvesting complex absorbs light energy and transfers it to the reaction centre." - CORRECT
This is the primary role of antenna complexes (also called light-harvesting complexes or LHC). They absorb photons and funnel the excitation energy to the reaction center chlorophylls (e.g., P680 in PSII).
Statement B:"The first electron is released from P680 and transferred to QA to produce a semiquinone QB⁻."  - INCORRECT
P680 is the reaction center chlorophyll of Photosystem II (PSII). After excitation, it donates an electron to a series of acceptors in the following order:
                             P680* → Pheophytin → QA → QB
QA is the first plastoquinone electron acceptor and becomes QA⁻. Then the electron is transferred to QB, forming QB⁻, and with a second electron, QBH₂.
The semquinone QB⁻ forms after QA, not at QA.
Hence, the statement is partially incorrect, and confuses the sequence.
Statement C: "D1, a protein subunit of the plant PSII core complex, is encoded by gene psbD."  - INCORRECT
D1 protein is indeed a key subunit of Photosystem II. However, it is encoded by the gene psbA, not psbD. psbD encodes the D2 protein, which is another component of the PSII reaction center. So, this statement is factually incorrect.

Final answer -
Incorrect statements: B and C 

Correct answer - Option b - B and C

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