BIOL 101 Guided Reading Questions GRQs Complete and submit this GRQ as a PDF before lecture and before your online Mastering Assignment L8 GRQs Photosynthesis Reading objectives Describe the two parts of photosynthesis and the inputs and outputs of both parts Explain what kind of sunlight is used by the plant and why sunlight is necessary Explain photophosphorylation in the light reactions of photosynthesis and describe how photophosphorylation is similar and different from the oxidative phosphorylation in aerobic respiration Module 7 5 Photosynthesis occurs in two stages which are linked by ATP and NADPH 1 Describe in words what happens in the light reaction of photosynthesis in the light reactions solar energy is absorbed by chlorophyll in the chloroplasts exciting electrons These excited electrons move through two photosystems which are connected by an electron transport chain The energy released during electron transport is used to pump H ions into the thylakoid space creating a gradient that powers ATP production At the same time electrons reduce NADP to NADPH Water is split to replace the lost electrons releasing oxygen as a by product 2 How is the Calvin cycle linked to the light reaction The Calvin cycle depends on the products of the light reaction ATP and NADPH These molecules provide the energy and reducing power required to convert carbon dioxide into glucose during the Calvin cycle 3 Examine figure 7 5B and describe it aloud Try to then look away and replicate similar drawing here in pencil Correct it until you have all the inputs and outputs of both parts Modules 7 6 7 8 Visible radiation absorbed by pigmetns druves the light reaction Photosystems capture solar energy Two photosystems connected by an electron transport chain convert light energy to the chemical energy of ATP and NADPH 1 What kind of visible light do plants NOT absorb well Why do plants have various pigments in the chloroplast Plants do not absorb green light well this is why they appear green as green light is reflected Plants have various pigments like chlorophyll a chlorophyll b and carotenoids to capture a broader spectrum of sunlight maximizing their ability to perform photosynthesis 2 Describe what light does in a photosystem by writing a detailed legend for fig 7 7B BIOL 101 Guided Reading Questions GRQs Complete and submit this GRQ as a PDF before lecture and before your online Mastering Assignment In a photosystem light energy excites electrons in chlorophyll which raises the electrons to a higher energy state These electrons are then transferred through the electron transport chain releasing energy to produce ATP and NADPH 3 Describe Figure 7 8 a mechanical analogy What is the big picture relative to electrons The electrons in photosynthesis are like a bucket brigade where one electron gets passed down a chain As they move through the electron transport chain they lose energy which is harnessed to create a proton gradient used to synthesize ATP Module 7 9 The light reactions take place within the thylakoid membranes 1 Electrons flow from water ultimately to NADP which is reduced to NADPH 2 Just like in aerobic respiration the electrons lose small amounts of energy as they bounce from one electron carrier to the next That released energy is used to do what cellular work The energy is used to pump H ions across the thylakoid membrane creating a proton gradient that powers ATP synthesis through chemiosmosis 3 Similar to mitochondria during aerobic respiration a H gradient is generated across membranes meaning there are more H on one side than the other In the chloroplast in what compartment do more H build up in thylakoid space 4 These H then flow through what protein ATP Synthase as they follow their concentration gradient from high to low What product of the light reaction has just been made as a result of the H gradient 5 Electrons in photosystem II would eventually be used up if not replaced Water plays a role in replacing electrons How Water is split photolysis providing electrons to replace those lost in Photosystem II and releasing oxygen as a by product 6 What part of the water molecule is used in the process and what part diffuses away electrons oxygen 7 Look at your overview fig 7 5B again Have you learned all the inputs and outputs of the light dependent reaction yet Be sure to review Let s consider the last output NADPH After electrons bounce through the electron transfer chain following photosystem II they have lost considerable energy They get re excited at photosystem I and get passed to another electron transfer chain What in this reaction NADP is the terminal electron acceptor 8 What is it called once it is reduced NADPH Is it useful to the cell Why carries high energy electrons required for the Calvin cycle to synthesize glucose BIOL 101 Guided Reading Questions GRQs Complete and submit this GRQ as a PDF before lecture and before your online Mastering Assignment Module 7 10 ATP and NADPH power sugar synthesis in the Calvin Cycle 1 The Calvin cycle takes place where in the chloroplast stroma 2 What is the chemical formula for glucose C6H12O6 So how many carbons are in the molecule 6 Therefore how many carbon dioxide molecules will be needed from the atmosphere 6 3 Taking carbon from the carbon dioxide in the air called an inorganic molecule and attaching the carbon to an organic molecule is called carbon fixation In the chloroplast the enzyme that performs this process is called rubisco the name of 4 For the purpose of introductory biology we want to take away the major points of the Calvin cycle a How many ATP total are needed to make one glucose 18 ATP b How many NADPH are needed to convert total to make one glucose 12 NADPH c How can the chloroplast get more ATP and NADPH from the light reactions during photosynthesis Modules 37 19 and 38 4 The carbon cycle depends on photosynthesis and respiration Human activities are responsible for rising concentrations of greenhouse gases 1 Look at your fingernail and think about the protein keratin that makes it Keratin is an organic molecule consisting of many carbon atoms Where did those carbon atoms come from CO2 in the atmosphere 2 How does photosynthesis remove carbon dioxide from the air plants take in CO2 to produce glucose 3 What happens to carbon in the wood of a tree when it is burned released back into the atmosphere as CO2 things that List increase CO2 in the atmosphere List things that remove CO2 from the atmosphere
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