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75 Cards in this Set
- Front
- Back
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What is the equation for Photosynthesis? |
6CO2 + 6H2O ------> C6H12O6 + 6O2 |
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What is the equation for Respiration? |
C6H12O6 + 6O2 ------> 6CO2 + 6H2O + ATP
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Name 5 things or which ATP is a source of energy? |
-Metabolic Processes like polypeptide and DNA/RNA synthesis -Movement (e.g. muscle contraction) -Active Transport -Secretion -Activation of molecules (e.g. activation of glucose in glycolysis) |
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Name 5 specific properties of ATP that makes it a good energysource |
- Releases small, manageable amounts of energy each time - Small, soluble molecule easily transported around cell - Easily broken down in one simple step so energy is easily released - Can transfer energy to another molecule by transferring one of its phosphate groups - ATP cannot pass out of the cell or be stored so it is an immediate energy supply for the cell |
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Why is ATP referred to as an immediate energy source? |
ATP can't be stored so releases its energy rapidly -This energy is released in a single step and is transferred directly to the reaction requiring it |
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Explain how ATP can make an enzyme-catalysed reaction take place more readily |
-ATP provides a phosphate that can attach to another molecule, making it more reactive and so lowering the activation energy -As enzymes work by lowering the activation energy of reactions, they have less 'work' to do |
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State 3 roles of ATP in plant cells |
-Active Transport -Activation of molecules -Metabolic processes like building up polypeptides from amino acids |
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Describe how the synthesis and breakdown of ATP meets the energy needs of a cell |
ATP is synthesised from ADP and Inorganic phosphate (1) Using energy from energy-releasing reactions like respiration (2) The energy is stored in the phosphate bond(3) ATP synthase catalyses this reaction(4) ATP then diffuses to the required part of the cell(5) where is is broken back into ADP and inorganic phosphate (6) Which is catalysed by ATPase(7) Chemical energy is released by the phosphate bond and used by the cell(8) |
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Define respiration |
The process in which plant and animal cells release energy from glucose |
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Define Photosynthesis |
The process in which plant cells use light energy to make glucose from carbon dioxide and water |
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Name 5 specific properties of ATP that makes it a good energy source |
Releases in small manageable amounts so none is wasted -Small and soluble so is easily transported round cell -Easily hydrolysed so energy easily and immediately released -it can transfer energy to other molecules by transferring a phosphate group -can't pass out cell so cell always has immediate supply of energy -once ATP breaks down to ADP+Pi to release energy, it can go back to ATP with energy (recycled) |
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What is the Coenzyme used in photosynthesis? |
NADP |
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Name the components of a chloroplast molecule |
-Double membrane (chloroplast envelope consisting of the inner and outer membrane) -Grana, made up of Thylakoid stacks -Stroma -Starch grains -Lamella |
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Where does the LIR of photosynthesis take place? |
The stroma of a chloroplast |
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Where does the LDR of photosynthesis take place? |
The thylakoid membrane in the chloroplast |
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What are the 2 types of phosphorylation in the LDR of photosynthesis? |
Cyclic and Non-Cyclic |
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Which photosystem does cyclic phosphorylation use? |
PSI |
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Name 3 photosynthetic pigments found in chloroplasts |
-Chlorophyll a -Chlorophyll b -Carotene |
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What wavelength of light does Photosystem I absorb the best? |
700nm |
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What wavelength of light does Photosystem II absorb the best? |
680nm |
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Describe the 1st stage of the LDR of photosynthesis |
-Light energy is absorbed by pigment in PSII -This energy excited electrons in chlorophyll and they move to a higher energy state where they are accepted by electron carrier molecule and begin to move down an electron transport chain to PSI |
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Describe the 2nd stage of the LDR of photosynthesis |
As the electrons leave PSII, they must be replaced in order for chlorophyll to carry on absorbing light -Light energy is then used to split a water molecule into electrons, protons (hydrogen) and oxygen, this is called photolysis -the electrons produced here replace the lost ones in PSII |
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Describe the 3rd stage of the LDR of photosynthesis |
Each electron carrier molecule in the chain is at a slightly lower energy level than the last; this means electrons lose energy as they move down the chain -this energy is used to synthesise ATP (this occurs when energy from electrons is used to pump hydrogen ions into the thylakoid, this creates a higher concentration of protons in the thylakoid than the stroma, creating a concentration gradient -as the protons move back into the stroma, they go through ATP synthase, the energy from this motion combines ADP +Pi to form ATP |
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Describe the 4th stage of the LDR of photosynthesis
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Light energy is then absorbed by PSI which excites electrons to an even higher energy state where they are accepted by NADP along with a hydrogen ion (proton) from the stroma, formingReduced NADP |
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What is a photosystem? |
Photosynthetic pigments attached to proteins on the thylakoid membrane |
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What happens during cyclic phosphorylation? |
-Only uses PSI -Electrons do not move onto NADP, they are transported back to PSI via carrier molecules - this means the electrons are recycled and repeatedly flow through PSI -this doesn't produce any reduced NADP or Oxygen, only small amounts of ATP |
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What are the raw materials for LDR of photosynthesis? |
-CO2 - -Water -Light energy |
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What are the products of the LDR of photosynthesis? |
-Reduced NADP -ATP -Oxygen as a waste product or goes on to be used inrespiration |
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What types of organic substance oes the LIR of photosynthesis make? |
-Carbohydrates (e.g. 2 TP molecules to make hexose sugar, glucose) -Lipids (e.g. TP can be used to make glycerol)-Proteins (e.g. Some amino acids are made from GP to join together to form proteins) |
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What is the 1st stage of the LIR of photosynthesis |
CO2 diffuses into leaf through stomata and dissolves in water around walls of mesophyll, then diffuses into stroma of chloroplast -CO2(1C) then combines with RuBP(5C) to form an unstable 6C compound which quickly breaks into 2 molecules of GP(3C) -This reaction between CO2 and RuBP is catalysed by Rubisco |
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What is the 2nd stage of the LIR of photosynthesis? |
- ATP from the LDR provides energy to turn GP(3C) into TP(3C) with the donation of a
hydrogen from Reduced NADP and so GP has been reduced -TP is then converted into useful organic compounds like glucose |
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What is the 3rd stage of the LIR of photosynthesis? |
-5 of every 6 molecules of TP are used to regenerate RuBP -The remaining ATP from the LDR are used to regenerate RuBP |
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What does RuBP stand for? |
Ribulose Bisphosphate |
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What does TP stand for? |
Triose Phosphate |
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What does GP stand for? |
Glycerate 3-Phosphate |
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What does Rubisco stand for? |
Ribulose Bisphosphate Carboxylase |
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How may TP molecules are needed to make 1 glucose molecule? |
3 |
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How many times must the carbon cycle turn to produce one hexose sugar and why? |
6
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How many carbon atoms are in RuBP? |
5
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How many carbon atoms are in TP? |
3
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How many carbon atoms are in GP?
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3 |
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How many carbon atoms are in Glucose?
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6 |
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What enzyme is used to synthesise ATP? |
ATP Synthase |
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What enzyme is used to break down ATP? |
ATPase |
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How many ATP molecules would be needed to make 1 hexose sugar? |
18 |
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How many Reduced NADP molecules would be needed to make 1 hexose sugar? |
12 |
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How many CO2 molecules would be needed to make 1 hexose sugar? |
6 |
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How arechloroplastsadapted for theLDR ofphotosynthesis?
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-Thylakoid membranes provide large SA for attachment of chlorophyll, electron carriers and enzymes -Network of proteins in grana hold chlorophyll in very precise manner to allow maximum absorption of light -Granal membranes have enzymes attached to help synthesise ATP (ATP synthase) -Chloroplasts contain both DNA and Ribosomes and so can quickly and easily manufacture proteins needed for LDR |
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How arechloroplastsadapted for theLIR ofphotosynthesis? |
Fluid of stroma contains all enzymes needed for LIR - Stroma surrounds the grana so products of LDR can readily diffuse into the stroma -It contains both DNA and Ribosomes so can quickly and easily manufacture proteins needed for LIR |
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Who worked out the LIR of photosyntheis? |
Melvin Calvin and his coworkers - hence the name 'Calvin Cycle' |
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What is theCalvinexperimentalso referred toand why? |
The 'Lollipop'Experiment asthe apparatushe used lookedlike a lollipop |
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Explain whathappened inCalvin'sLollipopexperiment? |
Single-celled Algae were grown under light in a thin transparent 'Lollipop' -Radioactive Hydrogen carbonate was injected into the 'lollipop' to supply the algae with radioactive carbon dioxide -At 5 second intervals, samples of the photosynthesising algae were dropped into hot methanol to stop all chemical reactions instantly -The compounds in the algae were then separated out using chromatography and those that were radioactive were identified |
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Why did Calvin use radioactive hydrogen carbonate in his experiment? |
To allow the substancesto which the radioactiveCO2 becomesincorporated to beidentified and thesequence of substancesproduced to be identified |
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What is thelaw oflimitingfactors? |
At any given moment,the rate of aphysiological processis limited by the factorthat is at its leastfavourable value |
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What are the 2main waysphotosynthesisis usuallymeasured? |
-The volume ofoxygen releasedby a plant -Thevolume of CO2taken up by a plant |
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What are theaverage idealconditions forphotosynthesis? |
-High light intensityat certainwavelength -Temperaturearound 25'C -CO2levels at 0.1% |
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What type oflight dochlorophyll a &b and Caroteneabsorb? |
_Red and Bluelight -Green lightis reflected andthat is why plantslook green |
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What happens tophotosynthesis ifthe temperatureis too high orlow? |
-If temp drops below around 10'C the enzymes (e.g. ATP Synthase and Rubsico) become inactive -If temperatures reach over around 45'C, these enzymes may start to denature -Also at high temps stomata start to close to avoid losing too much water and so less CO2 enters the leaf |
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What happensinphotosynthesiswhen CO2 levels are increased? |
Rate of photosynthesis increases as CO2 concentration increases (CO2 being used in calvin cycle) until about 0.4% - after this, the stomata may start to close, |
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What is theconcentrationof CO2 in theatmosphere? |
0.04% |
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What is thesaturationpoint? (interms oflimiting factors) |
-Where a factor isno longer limitingthe reaction -something elsehas become thelimiting factor |
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What is thecompensationpoint? (interms oflimiting factors) |
-When light intensity is a limiting factor and it is increased, volume of oxygen produced or CO2 taken up will increase to a point it is equal to the Oxgen and CO2 in respiration -There will be no exchange in or out of the plant at this point |
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What apparatuscan be used tomeasure thevolume of oxygenproduced inphotosynthesis? |
Photosynthometer (like a potometer) |
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In the experiment with the Potometer and the pond weed, why does the apparatus need to be airtight? |
Because any airescaping from theapparatus or notentering it will decreasethe volume of gasmeasured, giving anunreliable result |
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In the experiment with the Potometer and the pond weed, why does the temp of the water bath need to be kept constant? |
So any changes in therate of photosynthesiscan be said to be aresult of light intensity,not temperature astemp effects rate ofphotosynthesis |
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In the experiment withthe Potometer and thepond weed, why is itnecessary to do theexperiment in a darkroom with only thelamp as a light source? |
To prevent other lightfalling on the plant as thismay fluctuate and willaffect the light intensityand hence the rate ofphotosynthesis, leadingto unreliable results |
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In the experimentwith the Potometerand the pond weed,suggest why the plantis kept in the darkbefore theexperiment |
To preventphotosynthesis andto allow any oxygenproduced beforethe experiment, todisperse |
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In the experiment withthe Potometer and thepond weed, suggest whymeasuring the volume ofoxygen produced maynot be an accuratemeasure ofPhotosynthesis? |
Because the volume ofoxygen produced will beless than that produced byphotosynthesis as some ofthe oxygen will be used incellular respiration -Someoxygen may dissolve in thewater and not get counted |
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In the experiment withthe Potometer and thepond weed, suggestan advantage ofproviding an additionalsource of CO2 |
To ensure there issufficient CO2 forphotosynthesis, tostop it becoming alimiting factor |
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AP - How is thesequence ofElectron carriers ina chaindeterminedexperimentally? |
-Based on the fact that each transferof electrons is catalysed by a specificenzyme, by adding inhibitors tothese enzymes, we can see whichelectron transport molecules arereduced or oxidised -the electronmolecule that is always reduced isthe first in the chain and the one thatis last in the chain is always oxidised |
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How doesCyanideaffectrespiration? |
It is a non-competitiveinhibitor of an enzymein the electrontransport chain and soprevents electronsmoving down the chain |
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AP - What happenedin the experimentlooking at whererespiratory pathwaystake place usingCyanide? |
Mammilian liver cells were homogenised(broken up) and this was then centrifuged -Portions containing only nuclei, ribosomes,mitochondria and the remaining cytoplasmwere separated out -Samples of eachportion, and of the complete homogenatewere incubates with glucose or withglucose and cyanide or with pyruvate andcyanide or with pyruvate -After incubationthe presence or absence of CO2 andlactate were recorded |
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How docommercialfarmers dealwith CO2 beinga limiting factor? |
In glass houses, CO2is added to the air inhigher concentrations(could be done byburning somepropane in a CO2generator) |
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How docommercialfarmers deal withlight intensitybeing a limitingfactor? |
In glass houses, lightcan get through theglass and at nightthey use lamps toallow plants to carryon photosynthesising |
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How docommercialfarmers deal withtemperature beinga limiting factor? |
-Glass houses trap heat energyfrom the sunlight which warmsthe air -Heating and coolingsystems can also be installedto keep a constant optimumtemp -And air circulatorysystems to make sure thetemperature is eventhroughout the glass house |
