The photosynthetic pigments absorb the sunlight. In oxygenic photosynthesis, photosystem II is the chlorophyll-containing reaction center that carries out the light-induced transfer of electrons from water to plastoquinone. 2) This creates an e- deficiency in Photo II. Under high light conditions, however, Q A can accept two electrons and become doubly reduced, prompting the turnover of D1 (Keren et al., 1995). The ben… After excitement, e – is passed from PS-II (P 680) to primary electron acceptor (Pheophytin). for writing particulars on this page/marking responses. Jan 07,2021 - In light reaction, plastoquinone facilitates the transfer of electrons from:a)PS-I to NADP+b)PS-I to ATP synthasec)PS-II to Cytb6f complexd)Cytb6complex to PS-ICorrect answer is option 'C'. These photosystems absorb and utilize the solar energy efficiently in the thylakoid membranes. C water C plastoquinone (Pq) C plastocyanin (PC) C ATP C ferredoxin (Fd) light Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. Light of shorter wavelength (such as blue) has more energy than light of longer wavelength (such as red), so absorption of blue light creates an excited state of higher energy. Answer_and_Solution_NEET-2020_Code-G5(1).pdf, Delhi Technological University • POLS MISC, Ans_Solutions_NEET2020_(Code-H1)_qUFwey3.pdf, Delhi Technological University • FINANCE 101, Delhi Public School, R.K. Puram • BIOLOGY 123, Copyright © 2021. All cases of unfair means will be dealt with as per Rules and Regulations of this. Explain how during light reaction of photosynthesis, ATP synthesis is a chemiosmotic phenomenon. B) The light reactions provide ATP and NADPH to the carbon fixation step of the Calvin cycle, and the cycle provides water and electrons to the light reactions. The most common form of plastoquinone, known as PQ-A or PQ-9, is a 2,3-dimethyl-1,4-benzoquinone molecule with a side chain of nine isoprenylunits. In light reaction, plastoquinone facilitates the transfer of electrons from (1) Cytb 6f complex to PS-I (2) PS-I to NADP+ (3) PS-I to ATP synthase (4) PS-II to Cytb 6f complex Answer (4) Sol. Photosynthetic pigments are organized into clusters called photosystems. The steps of N.C. P.P. Activation of P 700 in photosystem I enables it to pick up electrons from the cytochrome b 6 /f complex (by way of plastocyanin — PC in the figure) and raise them to a sufficiently high redox potential that, after passing through … Do not make any stray marks on the, Answer Sheet. 17. It is composed of many molecules of chlorophyll a, chlorophyll b and carotenoids. A photosystem consists of 1) a light-harvesting complex and 2) a reaction center.   Terms. Photosystem II (PSII) functions to capture light energy and transfer it to plastoquinone, the first molecule in an electron transport chain that leads to the production of ATP. The reaction center chlorophyll contains electrons that can be transferred when excited. The light excites an electron from the chlorophyll a pair, which passes to the primary electron acceptor. Due to the higher midpoint potential of plastoquinone in the Q A site than Pheo − the charge-separated state is stabilized, reducing the probability of a back reaction between Q A − and P680 +. The pool of intermediate carriers may receive electrons from water via light reaction II and the quinones. Light energy absorbed by the antenna complex is transferred to reaction … The sunlight is transferred to the light-harvesting system found in the chloroplast. Bottom: schematic of the photosynthetic transfer chain in the thylakoid (Th) membrane of kleptoplasts in E. timida sea slugs. In light reaction,plastoquinone facilitates the transfer of electrons from : The oxygenation activity of RuBisCo enzyme in photorespiration leads to the formation of : The enzyme enterokinase helps in conversion of : Choose the correct pair from the following : (1) Exonucleases : Make cuts at specific positions within DNA. The product(s) of reaction catalyzed by nitrogenase in root nodules of leguminous plants is/are (1) Ammonia and oxygen (2) Ammonia and hydrogen (3) Ammonia alone (4) Nitrate alone Answer (2) Sol. Antenna Complex:It is light gathering part. In light reaction, plastoquinone facilitates transfer of electrons from PS-II to C y t b 6 f complex. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students. This preview shows page 1 - 3 out of 33 pages. Light reaction II leads to the oxidation of water, thus evolving oxygen (left bottom, Fig. Both cytochrome b ƒ –ƒ and plastoquinone (PQ) are oxidized by far red light and reduced by light of shorter wavelength. On completion of the test, the candidate must handover the Answer Sheet to the Invigilator before leaving, The candidates should ensure that the Answer Sheet is not folded. The electrons are transferred (by way of plastoquinone — PQ in the figure) to the cytochrome b 6 /f complex where they provide the energy for chemiosmosis. C) The light reactions supply the Calvin cycle with CO2 to produce sugars, and the Calvin cycle supplies the light reactions with sugars to produce ATP. Plastoquinone, in turn, transfers electrons to cyt b 6 f, which feeds them into PS I. Each candidate must show on demand his/her Admission Card to the Invigilator. 1).   Privacy As plastoquinone reduces the cytochrome b6f complex, the two protons it was carrying are released into the lumen. The process of photosynthesis: the light reactions Light absorption and energy transfer. The reaction center of PSII (called P680) delivers its high-energy electrons, one at the time, to the primary electron … copy number of the linked DNA in the vector. 2. light-reactions - 4 stages primary photoevent - light photon captured by pigment, exciting the electrons in the pigment; charge separation - energy transferred to reaction center (special chlorophyll pigment) transfers energetic electron to acceptor molecule, starts electron transport The light-saturated rate of photosynthetic O2 evolution in Chlamydomonas reinhardtii declined by approximately 75% on a per-cell basis after 4 d of P starvation or 1 d of S starvation. Photoreaction I transfer electrons Q10. N 2 + 8e– + 8H+ + 16ATP Mg 2NH 3 + H 2 + 16ADP + 16Pi Ammonia and Hydrogen. Course Hero is not sponsored or endorsed by any college or university. Pigments in the light-harvesting complex pass light energy to two special chlorophyll a molecules in the reaction center. Rough work is to be done on the space provided for this purpose in the Test Booklet only. | EduRev NEET Question is disucussed on EduRev Study Group by 128 NEET Students. Plastoquinone (PQ) is an isoprenoid quinone molecule involved in the electron transport chain in the light-dependent reactions of photosynthesis. The cytochrome complex, an enzyme composed of two protein complexes, transfers the electrons from the carrier molecule plastoquinone (Pq) to the protein plastocyanin (Pc), thus enabling both the transfer of protons across the thylakoid membrane and the transfer of electrons from PSII to PSI. There are other forms of plastoquinone, such as ones with shorter side chains like PQ-3 (which has 3 isoprenyl side units instead of 9) as well as analogs such as PQ-B, PQ-C, and PQ-D, which differ in their side chains. In addition to the two electrons, Qb also picks up two protons from the stroma. From primary e – acceptor, e – is passed to plastoquinone. 2. It uses the energy of sunlight to transfer electrons from water to a mobile electron carrier in the membrane called plastoquinone: H 2 O → P680 → P680 * → plastoquinone. Name the enzyme that facilitates opening of DNA helix during transcription. Ans: In the light reaction within the chloroplast, protons in the stroma decrease in number, while in the lumen there is accumulation of protons. Once excited, two electrons are transferred to plastoquinone Qb, the first mobile carrier. The key difference between plastoquinone and plastocyanin is that plastoquinone is a lipophilic carrier molecule that transfers electrons to plastocyanin through cytochrome b6f protein complex. One photon is needed to excite each of the electrons in this chlorophyll. 1), and the transfer of electrons from the water to an intermediate pool between Photosystem II and Photosystem I (middle Fig. This sunlight drives the process of photosynthesis. This system induces the continuous transfer of electrons through the light-absorbing molecules generally called chromophores (pigments), such as pheophytin, quinones, and chlorophyll. The cytochrome b6f complex, an enzyme composed of two protein complexes, transfers the electrons from the carrier molecule plastoquinone (Pq) to the protein plastocyanin (Pc), ultimately facilitating the transfer of electrons from PSII to PSI. It not only transfers the electrons for PS I but also is responsible for ATP production. 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