The Flow of Energy Part 3

8/14/2019 The Flow of Energy Part 3

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The Flow of Energy part 3

Photosynthesis


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6.2 Photosynthesis6.2 Photosynthesis The range of

colours whichmake up whitelight and are

visible to thehuman eye iscalled the VisibleSpectrum.

Infrared and

Ultraviolet wouldbe at either endof the spectrum

and are not visible

Longest WLShortest

WL


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Photosynthesis

Colour is a property of light that dependson wavelength. When light falls on anobject, some of it is absorbed and someis reflected. The apparent color of an

opaque object depends on thewavelength of the light that it reflects;e.g., a red object observed indaylight appears red because itreflects only the waves producing

red light. The color of a transparentobject is determined by the wavelengthof the light transmitted by it. An opaqueobject that reflects all wavelengthsappears white; one that absorbs allwavelengths appears black.


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White light is a mixtureof all wavelengths ofvisible light. Certainwavelengths of light

are absorbed by theleaf while others arereflected. When thereflected light reaches

your eye, the eye andbrain interpret themixture of reflectedwavelengths as color.


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White light is separatedinto the differentcolors (=wavelengths)of light by passing itthrough a prism.

Wavelength is definedas the distance frompeak to peak (ortrough to trough). Theenergy of is inverselyproportional to the

wavelength: longerwavelengths have lessenergy than doshorter ones.


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The order of colors isdetermined by thewavelength of light.Visible light is one small

part of theelectromagneticspectrum. The longer thewavelength of visiblelight, the more red the

color. Likewise theshorter wavelengths aretowards the violet side ofthe spectrum.Wavelengths longer than

red are referred to asinfrared, while those


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Chlorophyll

The intense greencolour ofchlorophyll is dueto its strongabsorbencies inthe red and blueregions of thespectrum, shown

in Because oftheseabsorbencies thelight it reflects

and transmitsa ears reen.


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Cartenoids

Carotenoids:Thisis a class ofaccessorypigments thatoccur in allphotosyntheticorganisms..Carotenoids

absorb lightmaximallybetween 460 nmand 550 nm and

appear red,oran e, or ellow


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Photosynthesis

Plants absorb a commongas called carbondioxide, pull water upthrough their roots anduse light to make sugar.

Plants use the sugar togrow. Plants give offoxygen as a by-product.The green parts of theplant makes the sugarand oxygen.

Carbon dioxide + water+ sunlight = sugar +oxygen

Watch video
http://www.youtube.com/watch?v=yBfx3OcXS6A&feature=fvwhttp://www.youtube.com/watch?v=yBfx3OcXS6A&feature=fvw


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. Both photosyntheticprokaryotes andeukaryotes have theseflattened sacs/vesiclescontaining photosyntheticchemicals. Only

eukaryotes havechloroplasts with asurrounding membrane.

Thylakoids are stacked likepancakes in stacks knowncollectively as grana. The

areas between grana arereferred to as stroma.While the mitochondrionhas two membranesystems, the chloroplasthas three, forming threecompartments.


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The Light Reactions

Photosynthesis is divided into 2 main sets ofreactions .

1. Light Reactions (Occurs in Grana)

The purpose of the light reactions is to

change light energy into chemical energyof ATP and NADPH (enzyme).

Light energy is absorbed and converted tochemical energy

Water is split into H+ ions, oxygen andelectrons

H+ from the water are attached to carrierco-enzymes (NADP) for use inphotosynthesis (see page 157)


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The Calvin Cycle AKA The DarkReactions

(Occurs in Stroma)

The purpose of the Calvin Cycleis to change CO2 into sugar by

adding energy & the H+ fromATP & NADPH.

a) Can occur in light or dark.

b) 6 CO2 & lots of ATP & NADPHare needed to make one sugarmolecule.

c) The sugar is then used for

plant growth or stored for use


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Energy Relationships

Respiration is almostthe exact oppositereaction tophotosynthesis.

These two reactionswork together tomaintain abiological balanceon earth. (I thinkthis diagram iseasier tounderstand than theone on page 160).


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Photosynthesis andRespiration.

Photosynthesis

produces food

stores energy

uses water

uses carbondioxide

releases oxygen occurs in sunlight

Respiration

uses food

releases energy

produces water

produces carbondioxide

uses oxygen occurs in the dark

as well as light


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Photosynthesis andRespiration.

Photosynthesis light energy

6CO2+6H20= C6H

12O6+6O2

Here is theequation forphotosynthesis.when a plant isexposed to 6

molecules ofcarbon dioxideand 6 moleculesof water and lightenergy is

present, glucose

Cellular Respiration

C6H12O6+6O2=CO2+H2O

notice that this equation isabout the opposite ofthe equation forphotosynthesis. This isbecause the products ofthe photosynthesisreactions are the

reactants of thereactions that take placeduring cellularrespiration. Conversely,the products of cellularrespiration are thereactants of the

photosynthesisreactions.


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Further Study

Here is a link to a goodslideshowtutorial

This is a good website explainingthe chemistry ofautumn colours
http://www.slideshare.net/MissWander/power-point-51-cell-energy-photosynthesis-respiration/1http://scifun.chem.wisc.edu/chemweek/fallcolr/fallcolr.htmlhttp://scifun.chem.wisc.edu/chemweek/fallcolr/fallcolr.htmlhttp://www.slideshare.net/MissWander/power-point-51-cell-energy-photosynthesis-respiration/1

The Flow of Energy Part 3

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