EXAM THREE SUMMER 2013 LECTURE 11 OBJECTIVES PHOTOSYNTHESIS PHOTOSYNTHESIS ROUTE BY WHICH VIRTUALLY ALL ENERGY ENTERS THE BIOSPHERE 3CO2 6H2O C3H6O3 3O2 3H2O IN THE PRESENCE OF LIGHT 1ST EVOLVED IN BACTERIA CYANOBACTERIA MODERN DAY PHOTOSYNTHETIC BACTERIA OXYGENIC PHOTOSYNTHESIS EVOLVED 2 5 BILLION YRS AGO PRECEDED BY PHOTOSYNTHETIC BACTERIA USE ELECTRON DONORS OTHER THAN WATER EX PURPLE SULFUR BACTERIA USE H2S ELEMENTAL SULFUR IS BYPRODUCT RATHER THAN OXYGEN OCCURS IN 2 SEPARATE RXNS LIGHT RXN TAKES PLACE ON THYLAKOID MEMBRANES OF THE CHLOROPLAST LIGHT CAPTURED BY CHLOROPHYLL LEADS TO ELECTRON TRANSPORT FORMATION OF ATP REDUCTION OF NADP NADPH ABSORPTION SPECTRUM LIGHT ABSORPTION PATTERN OF A PIGMENT ACTION SPECTRUM RANGE OF LIGHT THAT SPECIFIC LIGHT REQUIRING PROCESS OCCURS DRIVEN BY RED BLUE LIGHT PHOTOSYNTHETIC PIGMENTS CHLOROPHYLL A CYANOBACTERIA ALL PHOTOSYNTHETIC EUKARY B ACCESSORY PIGMENT NOT DIRECTLY INVOLVED IN ENERGY TRANSDUCTION SERVES TO BROADEN RANGE OF LIGHT USED CAROTENOIDS ANTIOXIDANT PROTECT CHLOROPLAST FROM PHOTOBLEACHING NEITHER CHLOROPHYLL B OR CAROTENOIDS CAN REPLACE CHLOROPHYLL A IN PHOTOSYSTEMS EMBEDDED IN THYLAKOID MEMBRANES PHOTOSYSTEMS ANTENNA COMPLEX PERIPHERY CAPTURES PHOTONS RXN CENTER CENTER SPLIT H20 2 PHOTOSYSTEMS 2 WATER SPLIT TO O2 2H 1 REDUCES NADP TO NADPH ATP IS MADE BETWEEN BOTH PHOTOSYSTEMS CALVIN CYCLE DARK RXN TAKES PLACE IN THE STROMA OF THE CHLOROPLAST FLUID FILLED SPACE FIXES CO2 INTO CARBS USING ATP NADPH FROM LIGHT RXN RuBP CO2 H2ORubisco 2 PGA RUBISCO CARRIES OUT CO2 FIXATION IS AN ENZYME CONVERTS A 5 CARBON SUGAR RuBP 2 3 CARBON SUGAR PGA 6 TURNS ON CYCLE 1 GLUCOSE EXCESS GLUCOSE IS STORED AS STARCH PHOTORESPIRATION CO2 IS LOW RUBISCO BINDS 02 BREAKS DOWN RuBP TO GLYCOLATE EVENTUALLY TO CO2 REDUCES PHOTOSYNTHETIC EFFICIENCY BY 30 40 RUBISCO HAS DUAL ACTIVITY CARBOXYLASE OXYGENASE OXYGENASE PHOTORESPIRATION UNWANTED OCCURS IN PEROXISOME MITOCHONDRIA WHEN TEMPERATURE IS HIGH C3 PLANTS SUFFER FROM THIS EX WHEAT OATS RICE C4 PLANTS SOLUTION TO PHOTORESPIRATION PROBLEM EX SUGAR CANE MAIZE TROPICAL PLANTS FIX CO2 4 CARBON COMPOUND MALATE SPATIAL SEPARATION OF CO2 FIXATION CALVIN CYCLE MESOPHYLL CELLS SITE OF CO2 FIXATION BUNDLE SHEATH CELLS SITE OF CALVIN CYCLE MORE EFFICIENT THAN C3 AT HIGH TEMPS MODERATELY DRY CONDITIONS CAM PLANTS C4 MODIFICATION TEMPORAL SEPARATION OF CO2 FIXATION CALVIN CYCLE CO2 FIXATION NIGHT STOMATA OPEN CALVIN CYCLE DAY STOMATA CLOSED USE MALATE TO FIX CO2 EX PINEAPPLE CACTUS SAVE H20 DRY HOT AREAS LECTURE 12 OBJECTIVES WATER NUTRIENT TRANSPORT TRANSPIRATION DEFINITION water loss in plants INEVITABLE ASPECT OF PHOTOSYNTHESIS IN LAND PLANTS gaseous CO2 must go into solution in water in the plant cell wall prior to entering the cells evaporation occurs when air hits the water MAIN ORGAN OF WATER LOSS leaves through the stomata pores on the epidermis AIDS PHOTOSYNTHESIS by cooling plants lowers tissue temperature which increases efficiency for C3 plants WATER MOVES THROUGH XYLEM stacked vessels for high volume water transport COHESION TENSION THEORY THEORY OF HOW THE FLUID MOVES IN THE XYLEM EVAPORATION TRANSPIRATION evaporation at the plant s surface produces a pull tension that s transmitted to the roots by the cohesiveness of water molecules outside air DRIVING FORCE difference in relative humidity between the inside of the leaf HYDROGEN BOND INTERACTION in water molecules creates the constant water stream to be pulled up the plant HUMIDITY water moves from high potential to lower potential ex if the leaves have a higher humidity water leaves the leaves water moves up from the roots leaves EVIDENCE FOR THIS THEORY 1 NEGATIVE PRESSURES IN THE TRUNK LEAVES CAN BE MEASURED 2 STEM DIAMETERS SHRINK DURING THE DAY INCREASE AT NIGHT diameter shrinks at upper trunk slightly before lower trunk because the pull is coming from the top TRANSPIRATION STREAM DEFINITION flow of water through the xylem WATER IS AVALIABLE THROUGH THE ROOTS WATER IS ABSORBED PASSIVELY BY ROOTS MINERALS ALSO TRANSPORTED ion uptake linked to transpiration photosynthesis CAVITATION RUPTURE OF WATER COLUMN PRODUCES AN EMBOLISM AIR ACTIVE during the day PASSIVE during the night STREAM CAN BE BROKEN BUBBLE can t move water VESSELS have perforation plates open system embolisms can spread TRACHEID restricted to one tracheid no perforation plates water passes through bordered pit pairs air is prevented from spreading to adjacent tracheid by surface tension of air water meniscus spanning pores in pit membrane MAXIMUM HEIGHT OF TREES IS 350 FT with more height there is a increase in tension increase in bubble chance ex redwoods TRANSPIRATION MUST BE REGULATED TURGOR PRESSURE maintains rigidity keeps plant erect OPEN CLOSE STOMATA RESPOND TO CO2 concentration light water OPENING OCCURS WHEN SOLUTES ARE ACTIVELY ACCUMULATED IN GUARD CELLS THAT SURROUND STOMATA INCREASE IONS water goes in turgid guard cells DECREASE IONS water goes out flaccid guard cells stoma open stoma closed K AND CL CHANNELS INVOLVED GUARD CELLS INNER VENTRAL WALL IS THICKER MORE RIGID THAN RADIALLY ORIENTED CELLULOSE MICROFIBRILS IN WALL OUTSIDE DORSAL prevent lateral expansion INCREASE IN TURGOR PRESSURE CAUSES OUTER WALLS TO MOVE OUTWARD RELATIVE TO INNER WALL PORE OPENS DECREASE IN TURGOR PRESSURE PORES CLOSE FACTORS AFFECTING RATE OF TRANSPIRATION HUMIDITY TEMPERATURE WIND LAYER OF CUTIN waxy substance on outer wall of epidermal cells IMPERVIOUS TO WATER CARBON DIOXIDE SURFACE AREA STOMATES OPEN OR CLOSED LEAF ADAPTATIONS EPIDERMIS LIMITS WATER LOSS CUTICLE PHOTOSYNTHETIC STEMS SUCCULENT LEAVES LEAVES REDUCED TO SPINES HAIRY LEAVES TRICHOMES XEROPHYTE CUTICLE C4 CAM PLANTS PLANTS ADAPTED TO GROW IN DRY ARID ENVIRONMENT MULTIPLE LAYER EPIDERMIS STOMATA ON UNDERSIDE SUNKEN IN W TRICHOME root hairs SPECIAL ADAPTATIONS TO MAINTAIN PHOTOSYNTHESIS WHILE LIMITING TRANSPIRATION have opposite stomata openings than other plants MOVEMENT OF SUGARS VIA PHLOEM SOURCE leaves storage structures SINKS fruits or storage structures SUCROSE IS TRANSPORTED SUGAR IN MOST PLANTS MAIN SINKS VEGETATIVE GROWING TISSUE REPRODUCTIVE FRUIT APHIDS EVIDENCE OF SUGAR MOVEMENT PHLOEM FEEDERS PATHWAY REQUIRES ENERGY ACTIVE TRANSPORT MESOPHYLL CELLS SIEVE TUBES THROUGH PLASMODESMATA CELL WALLS VIA SUCROSE PROTON CO TRANSPORT TRANSPORT OF PROTONS OUT OF CYTOPLASM OF CELLS GIVES ENERGY FOR SUCROSE MOVEMENTS PRESSURE FLOW HYPOTHESIS SUGARS FROM SOURCE SINK BY OSMOTICALLY GENERATED TURGOR PRESSURE 1 ACTIVELY
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