Reading Essentials for Biology Glencoe (794133), страница 24
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Write theanswer on the other side.Quiz yourself until you knowall the answers.1. What are the two partsof photosynthesis?________________________________________________92Chapter 9Plants and other green organisms must trap light energy fromthe sun to be able to use it. The energy must then be stored in aform that can be used by cells.
That form is ATP. The processplants use to trap and make energy from sunlight is called photosynthesis. During photosynthesis, plants use the sun’s energy tomake simple sugars. These sugars are then made into complexcarbohydrates, such as starch. These starches store energy.There are two parts to photosynthesis: light-dependent reactions and light-independent reactions.
The light-dependentreactions change light energy into chemical energy. This resultsin the splitting of water and the release of oxygen. The lightindependent reactions produce simple sugars.Where does photosynthesis take place?The chloroplast is the part of the plant’s leaf where photosynthesis takes place. The chloroplast contains pigments, which aremolecules that take in specific wavelengths of sunlight. Wavelengths of sunlight transfer energy. The most common pigmentin the chloroplast is chlorophyll.Chlorophyll is a plant pigment that absorbs most wavelengthsof sunlight except green. Because it cannot take in the greenwavelength, it reflects the green. This is what makes leaves lookgreen.
In the fall, leaves stop producing chlorophyll, so other pigments become visible. This gives leaves a wide variety of colors.READING ESSENTIALSCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.Trapping Energy from SunlightNameDateClassSection9.2Photosynthesis: Trapping the Sun’s Energy, continuedLight-Dependent Reactions2. What happens during theThe first phase of photosynthesis needs sunlight. The sunlightCalvin cycle?strikes the chlorophyll in the plant’s leaves and the energy fromthe sunlight is transferred to electrons in the chlorophyll. The________________________electrons move from the chlorophyll to an electron transport________________________chain.
An electron transport chain is a line of proteins embedded in a membrane along which the electrons are passed down.________________________Each protein in the line passes the electron to the next protein.As the electrons pass along this line, they losesome of their energy. If you filled a bucket withLight-Dependent Reactionswater and passed it along a line of people veryquickly, some of the water would spill out. This isSunsimilar to how the electrons lose their energy.Light energyCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.What happens to the lost energy?transfers to chlorophyll.The energy the electrons lose can beused to form ATP from ADP, which you learnedabout in the last section. Energy that is not usedto form ATP can be stored for use in the lightindependent reactions.
The energy is stored in anelectron carrier called NADPH, shown at theright. NADPH carries the energy to the lightindependent reactions.Chlorophyll passes energydown through theelectron transport chain.Light-Independent ReactionsThe second phase of photosynthesis does notneed sunlight. It takes place in the chloroplast andis called the Calvin cycle. The Calvin cycle usescarbon dioxide to form sugars. The sugars thenbecome stored energy. It is a large task for a cellto make sugars from carbon dioxide.
The ATPand NADPH produced in the light-dependentreactions are used. The chloroplast breaks downthis large task into very small steps. The end resultis energy that is stored in the plant as sugars.Organisms that eat plants use these sugars togive them energy. The energy is used in cellularrespiration, which you will learn about in thenext section.READING ESSENTIALSEnergized electrons provideenergy thatbondssplitsH2OH+NADP+oxygenreleasedPto ADPformingATPNADPHfor use in thelight-independent reactions.Chapter 993NameDateClassSection9.2Photosynthesis: Trapping the Sun’s Energy, continued◗ After You ReadMini GlossaryCalvin cycle: series of reactions during the lightindependent phase of photosynthesis inwhich sugars are formed from carbon dioxide using ATP and NADPH from the lightdependent reactionslight-dependent reactions: phase of photosynthesis where light energy is converted tochemical energy in the form of ATP; resultsin the splitting of water and the releaseof oxygenchlorophyll: light-absorbing pigment in plantsand some other green organisms that isrequired for photosynthesis; absorbs mostwavelengths of light except for greenlight-independent reactions: phase of photosynthesis where energy from light-dependentreactions is used to produce sugar and additional ATP moleculeselectron transport chain: series of proteinsembedded in a membrane along whichenergized electrons are transported; as electrons are passed from molecule to molecule,energy is releasedphotosynthesis: process by which plants andother green organisms trap energy fromsunlight with chlorophyll and use thisenergy to convert carbon dioxide and waterinto simple sugarspigments: molecules that absorb specific wavelengths of sunlight1.
Read the key terms and their definitions in the Mini Glossary above. Circle one of the keyterms and, in the space provided, define it in your own words.________________________________________________________________________________________________________________________________________________________________________2. Select one of the question headings in the Read to Learn section. Write the question in thespace below. Then write your answer to that question on the lines that follow.Question:Answer:____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________94Chapter 9READING ESSENTIALSCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.____________________________________________________________________________________NameDateClassSection9.2Photosynthesis: Trapping the Sun’s Energy, continued3.
Complete the concept diagram below using the following terms: ATP, Calvin cycle,chlorophyll, electron transport chain, light-dependent reactions, light-independentreactions, and NADPH.Phases of PhotosynthesisLight energy transfers toUse carbon dioxide toform sugars that are storedas energy in theCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.which passes the energythrough theLost energy isused to formstored asVisit the Glencoe Science Web site at science.glencoe.com to findyour biology book and learn more about photosynthesis.READING ESSENTIALSChapter 995NameDateClassSection9.3 Getting Energy to Make ATP◗ Before You ReadSC.B.1.4.1 The student understands how knowledge of energy is fundamental to all thescientific disciplines (e.g., the energy required for biological processes in living organismsand the energy required for building, erosion, and rebuilding of the Earth). SC.G.1.4.3The student knows that the chemical elements that make up the molecules of livingthings are combined and recombined in different ways.
Also covers SC.F.1.4.1, SC.F.1.4.3You have learned that during photosynthesis, plants use the sun’s energy to produce sugars that provide energy. Plants convert the sugars into carbohydrates to store energy. Humans cannot directlyconvert sunlight into energy. Yet the human body can use the energy stored in plants. On the linesbelow, list your favorite foods that come from a plant source.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________◗ Read to LearnIdentify Stagesof Cellular RespirationCircle the name of each stageof cellular respiration. Place anumber (1, 2, or 3) in the margin to indicate the stage.1.
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