Concept explainers
The water necessary for photosynthesis
- a. is split into H2 and O2.
- b. is directly involved in the synthesis of carbohydrates.
- c. provides the electrons to replace those lost in photosystem II.
- d. provides the H + needed to synthesize G3P.
- e. does none of the above.
Introduction: The water molecule is essential in photosynthesis. It splits into hydrogen ions and oxygen, and provide electrons to replace the lost electrons from the photosystem II during the light reaction. This reaction is called photolysis of water. The protons can be used to produce ATP through ATP synthase.
Answer to Problem 1TY
Correct answer: The water present in the photosynthesis provides the electrons to replace the loss of electrons in the photosystem II. Hence, the correct answer is option c.
Explanation of Solution
Reason for correct answer:
Option c. is given as “provides the electrons to replace those lost in photosystem II”.
The photolysis of water provides electrons to replace the lost electrons in the photosystem II. It dissociates into hydrogen ions and oxygen. During this reaction, the electrons produced from the hydrogen ions are used to replace the electrons lost in the photosystem II. Hence, the correct answer is option c.
Reasons for the incorrect answer:
Option a. is given as “is split into H2 and O2”.
The water is split into oxygen and hydrogen ions and not hydrogen gas. This is because the electrons gained from the formation of hydrogen ions are provided to replace lost electrons in the photosystem II. Hence, option a. is incorrect.
Option b. is given as “is directly involved in the synthesis of carbohydrates”.
The water molecule is not directly involved in the synthesis of carbohydrates. It only provides electrons for the photosystem II. The molecule of carbon dioxide serves as the direct fuel for the production of carbohydrates. Hence, option b. is incorrect.
Option d. is given as “provides the H+ needed to synthesize G3P”.
Water provides electrons to the photosystem II. G3P is synthesized by the reduction and dephosphorylation of 1,3 biphosphoglycerate which is further coupled with the oxidation of NADH. Hence, option d. is incorrect.
Option e. is given as “does none of the above”.
Water does provide an electron to the reaction centre and it is used for the production of energy using light. It also splits into hydrogen ions and single oxygen atoms which then forms oxygen gas. The oxygen produced is liberated as the by-product of photosynthesis. Hence, option e. is incorrect.
Hence, the options a., b., d., and e. are incorrect.
Water dissociates into the single oxygen atom and hydrogen ions liberates electron. The released electron is captured by the photosystem II. The electron then passes to the primary electron acceptor and finally to the photosystem I. Photosystem I uses it to produce energy in the form of ATP and NADPH.
Want to see more full solutions like this?
Chapter 8 Solutions
BIOLOGY-TEXT
Additional Science Textbook Solutions
Biological Science (6th Edition)
Laboratory Manual For Human Anatomy & Physiology
Campbell Biology in Focus (2nd Edition)
General, Organic, and Biological Chemistry - 4th edition
SEELEY'S ANATOMY+PHYSIOLOGY
Biology: Life on Earth with Physiology (11th Edition)
- Which of the following descriptions about photorespiration is not correct? Select one: a. Rubisco binds O2 instead of CO2. b. Carbon dioxide is released without producing ATP. c. It limits damaging products of light reactions that build up in the absence of the Calvin cycle at low CO2 concentrations. d. Peroxisomes and mitochondria rearrange and split the compound made by rubisco to fix CO2. e. It occurs in hot and dry conditions.arrow_forward1. In chloroplasts, the enzyme ATP synthase couples the synthesis of ATP to: a. the diffusion of protons. b. the reduction of NADP+. c. the excitation of chlorophyll. d. the reduction of chlorophyll e. the transfer of electrons. 2. In the two-dimensional paper chromatography technique used by Calvin and Benson, a substance that ends up in the middle of the paper means that: a. it is insoluble in one of the solvents. b. it is an impure substance. c. it is too large to migrate all the way across the paper. d. it migrates roughly half way across the paper in both solvents. e. it is a relatively large and charged molecule. In chloroplasts, an electron being passed down the electron transport chain may have originated from: photosystem I. photosystem II. NADPH. both a and b. a, b, and c If we are able to follow a single electron that has just been ejected from the reactive center of photosystem II, which of the following is a feasible pathway…arrow_forwardThe role of photosystem 1 and photosystem 2 in the process of photosynthesis is to a. absorb sunlight and distribute the energy as heat b. absorb sunlight and transfer the energy to electrons c. form ATP as hydrogen ions cross the thylakoid membrane d. transfer electrons to form NADPHarrow_forward
- Which of the following is true of light-independent reactions of photosynthesis? Select all that apply. a. Light-independent reactions occur in the stroma. b. Water molecules are split during light-independent reactions. c. Chlorophyll absorbs energy from sunlight. d. Carbon dioxide is necessary for light-independent reactions.arrow_forwardWhich of the following options best explains how less chlorophyll would affect the proces of photosynthesis in plants? 6. A. It would increase the rate of photosynthesis because of the increased production of food. B. It would limit the amount water plants are able to take in, resulting in a slower rate of photosynthesis. C. It would increase the production of oxygen because the plant would need to work hard to feed themselves. С. D. It would limit the amount of light absorbed by the plant and decrease the amount of food the plant is able to produce for itself.arrow_forwardDuring oxygenic photosynthesis in plants, the hydrogen atoms that end up in product carbohydratemolecules are coming from which of the following substrate molecules?A. water molecules (H2O)B. sucrose sugars (C12H22O11)C. carbon monoxide (CO)D. glucose sugars (C6H12O6)E. carbon dioxide (CO2)arrow_forward
- The excited electron from photosystem I a. can be returned to the reaction center to generate ATP by cyclic photophosphorylation. b. is replaced by oxidizing H2O. c. is replaced by an electron from photosystem II. d. Both a and c are correct.arrow_forwardWhich of the following structures is not a component of a photosystem? a. ATP synthase b. antenna molecule c. reaction center d. primary electron acceptorarrow_forwardBoth the light reactions and light-independent reactions of photosynthesis… Select one: a. None of the options are true. b. use NADPH. c. fix CO2. d. synthesize ATP. e. rely on electron transport.arrow_forward
- Explain why each of the following misconceptions about photosynthesis is false: a. Only plants are autotrophs. b. Plants do not need cellular respiration because they carry out photosynthesis. c. Chlorophyll is the only plant pigment.arrow_forwardWhich of the following descriptions about photosystems during linear electron flow is not correct? Select one: a. energy required for ATP synthesis is provided when electrons pass through the electron transport chain from photosystem I b. photosystem II works before photosystem I c. P680 is the chlorophyll a pair that exists in photosystemII d. the primary electron acceptor receives electrons from P680 or P700 e. P680+ receives electrons from the splitting of waterarrow_forwardWhich of the following changes would decrease ATP production in the light-dependent reactions of photosynthesis? a. decreasing the pH of the thylakoid lumen b. decreasing the pH of the chloroplast stroma c. increasing the concentration of NADP+ in the chloroplast stroma d. making the thylakoid membrane freely permeable to protons by adding a proton channel e. two of the above would decrease ATP productionarrow_forward
- Human Anatomy & Physiology (11th Edition)BiologyISBN:9780134580999Author:Elaine N. Marieb, Katja N. HoehnPublisher:PEARSONBiology 2eBiologyISBN:9781947172517Author:Matthew Douglas, Jung Choi, Mary Ann ClarkPublisher:OpenStaxAnatomy & PhysiologyBiologyISBN:9781259398629Author:McKinley, Michael P., O'loughlin, Valerie Dean, Bidle, Theresa StouterPublisher:Mcgraw Hill Education,
- Molecular Biology of the Cell (Sixth Edition)BiologyISBN:9780815344322Author:Bruce Alberts, Alexander D. Johnson, Julian Lewis, David Morgan, Martin Raff, Keith Roberts, Peter WalterPublisher:W. W. Norton & CompanyLaboratory Manual For Human Anatomy & PhysiologyBiologyISBN:9781260159363Author:Martin, Terry R., Prentice-craver, CynthiaPublisher:McGraw-Hill Publishing Co.Inquiry Into Life (16th Edition)BiologyISBN:9781260231700Author:Sylvia S. Mader, Michael WindelspechtPublisher:McGraw Hill Education