Guided Reading Q s Lesson 8 Photosynthesis 1 Describe in words what happened in the light reaction of photosynthesis The light reaction of photosynthesis is the first of 2 parts of photosynthesis the steps in which solar energy is absorbed and converted to the chemical energy of ATP and NADPH releasing oxygen in the process 2 How is the Calvin Cycle linked to the light reaction The second part of photosynthesis comes after the light reaction and it is called the Calvin Cycle This is when a cyclic series of chemical reactions that occur in the stroma of a chloroplast using the carbon in CO2 and the ATP and the NADPH produced by the light reactions to make the energy rich sugar molecule G3P 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 of the inputs and outputs of both parts 4 What kind of visible light do plants NOT absorb well Why do plants have various pigments in the chloroplast Green light us not absorbed well however it is reflected Which is why we see green Chloroplast has more than one type of pigments chlorophyll a b are some examples 5 Describe what light does in a photosystem by writing a detailed legend for fig 7 7B Light in a photosystem transfers energy through pigment molecules with in the light harvesting complexes Pigments molecules with the light energy goes through the reaction center and taken in by a primary electron acceptor 6 Before looking at the details of electron transport and chemiosmosis of module 7 9 describe Figure 7 8 a mechanical analogy A What is the big picture relative to electrons The electrons in this mechanical analogy are taken through photosystems 1 and 2 Photons activate the electrons transportations excelling them to higher levels of the photosystem As the electrons travel on the chain from Photosystems 2 to 1 it loses energy due to ATP gaining from it Once the electron enters photosystem 1 another photon activates the electrons giving it energy to boost to the higher level to them relinquish energy for NADPH B Electrons flow from ultimately to which is reduced to Electron transport chain NADP NADPH 7 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 Create ATP 8 Similar to mitochondria during aerobic respiration an 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 These H then flow through what protein 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 Thylakoid space ATP synthase ATP is created 9 Electrons in photosystem II would eventually be used up if not replaced Water plays a role in replacing electrons A How Water is split B What part of the water molecule is used in the process and what part diffuses away Oxygen is released while H ions are used in the process 10 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 reexcited at photosystem I and get passed to another electron transfer chain A What is the terminal electron acceptor in this reaction NADP B What is it called once it is reduced NADPH C Is it useful to the cell Why It helps to transport electrons 11 The Calvin cycle takes place where in the chloroplast What is the chemical formula for glucose So how many carbons are in the molecule Therefore how many carbon dioxide molecules will be needed from the atmosphere Stroma C6H12O6 6 6 12 Taking carbon from the carbon dioxide in the air called an inorganic molecule and attaching the carbon to an organic molecule is called In the chloroplast the name of the enzyme that performs this process is called Carbon fixation Rubisco For the purpose of intro biology we want to take away the major points of the Calvin cycle How many ATP total are needed to make one glucose 18 How many NADPH are needed to convert total to make one glucose 12 How can the chloroplast get more ATP and NADPH From H2O in the thylakoid discs 14 A How does photosynthesis remove carbon dioxide from the air Stored in organic molecules carbs B What happens to carbon in the wood of a tree when it is burned Combustion rapidly releases energy as heat and CO2 List things that increase CO2 in the atmosphere and things that remove CO 2 from the atmosphere Increase CO2 Decrease CO2 Fossil fuels Burning of wood 15 What is the global consequence for the atmosphere is CO 2 output by respiration exceeds its intake by photosynthesis and absorption into the ocean Climate change and global warming 16 What happens to the oceans as they absorb more and more CO2 CO2 dissolved in water equals carbonic acid PH in ocean decreases affecting marine life and ocean concentrations 17 Label A Light energy B Light reactions C Calvin cycle D O2 is released E Electron transport chain F NAPH G ATP H G3P sugar
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