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41 Cards in this Set
- Front
- Back
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Suggest reasons why 95% of the light hitting thesurface of a leaf is not used by the chloroplasts. |
*Reflection;*incorrect wavelength/colour/ frequency; *light doesn’t hit the chloroplast/chlorophyll, it is transmitted; *light being in excess e.g. at max.photosynthesis so no more light can be used. |
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Describe the structures in a chloroplast thatare involved in the LD reactions |
TheLD reactions involve the *thylakoidsthat are arranged into stacks of granum. *The grana are connected by lamellae.The *thylakoid membrane contains electron carriers, proteins and*photosynthetic pigments such as chlorophyll which are *arranged intophotosystems/quantasomes; the membrane also has *ATPase/ ATPase channels. |
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Explain how the energy from light is madeavailable in ATP molecules for the synthesis of organic materials. (6) |
*Thelight dependent reactions occurin the thylakoids *in the granum in *accessory pigments such aschlorophyll. The process begins when *light energy raises the energy level of two electronsso that they are excited, the electrons are then *released from thechlorophyll/ photosystem. They then travel down the *electron carrier chain, travelling to eachcarrier molecule through a series of *oxidation and reduction (redox)reactions, releasing energy/ *the electrons’ energy level falls. The energyreleased is used to *synthesiseATP from ADP and an organic phosphate ion *(phosphorylation); the *enzymesynthase/ synthetase isneeded to make the ATP. *Photolysis of water produces 2 electrons which areused to replace those lost from the chlorophyll. |
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Explain how oxygen is produced during thelight-dependent reactions of photosynthesis. (2) |
Using*energy from light the *photolysis *of water occurs that produces/releasesoxygen |
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The products of the light-dependent reactionsthat are used in the light-independent reactions are reduced NADP and....
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ATP |
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Oxygen is produced when water molecules aresplit in the process of…… |
Photolysis |
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When light is absorbed by chlorophyll, itexcites……. |
electrons |
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RuBP combines with carbon dioxide in…… |
Thelight-independent reactions of the Calvin cycle. |
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RUBISCO..... |
is the enzyme that catalyses carbon fixation. |
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Carbon fixation takes place in….. |
thestroma of a chloroplast. |
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Explain why the light-independent stage cannottake place without the light-dependent stage. (3) |
Becausethe *products of thelight-dependent stage are needed for/used in the light-independent stage/Calvincycle. *Thee products of the light-dependent stage are reduced NADP and ATP, *rNADP is usedin the reduction GP/carbon dioxide whilst *ATP is used as a source of energy.bidi-蝞T |
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Suggest why the development of plants depends onthe rate of carbon fixation. (3) |
*Carbonfixation produces {GP / eq}, this *product is converted to glucose/ starch/ eq.*The faster the C- Fixation the faster the glucose/ starch production, as the *rate of growth of a plant isdependent on the rate of C-Fixation, if this increases so will the *GPPof the crop/plant.. |
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Suggest how GALP may be used to synthesisecellulose. (5) |
*GALP is a3C molecule that is used in the formation of *glucose a 6C sugar. *This synthesis involvesenzymes; to make cellulose enzymes are also needed. *Celluloseconsists of ß-glucose molecules that are joined by *1-4 *glycosidic bonds in *condensationreactions. *Cellulose is a polysaccharide (long chain molecule) and is an *unbranched molecule;each cellulose chain is then joined together in condensation reactions with 1-6 hydrogen bonds. |
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The rate of carbon fixation is higher at 25°C than at 14°C for eachof the six varieties of maize.Suggest an explanation for this. (2) |
*Temperaturechange affects the kinetic energy/movement of molecules/particles *thereforethis effects number of collisions/enzyme-substrate complexes. |
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The difference between abiotic and bioticfactors is that….. |
bioticfactors involve organisms/living things whereas abiotic are physical/chemical/non-livingfactors |
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A species consists of…….. |
individualswho can interbreed to produce fertile offspring |
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Net primary productivity is….. |
the rate at which energy is incorporated into biomass/ organic material in*producers/ plants, *as there may be losses due to respiration (GPP- R) |
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The metabolic process that best describes theprocess that accounts for most of the difference between GPP and NPP in plantsis.... |
……..Respirationt b;bT |
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Suggest two biotic factors that may influenceNPP in grassland. (2) |
*Grazingby consumers/herbivores/named herbivore; *trampling; *shading by other plants/namedplant; *competition from other plants; *disease. ȝ!T |
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Suggest how other animal populations of ahabitat may be affected by changes in a lizardpopulation. (2) |
*Theirprey may increase in number as *fewer are eaten by the lizard. *Other carnivoresmay increase *because there is less competition for food (from lizards),however the *lizards’ predator may decrease/eat other prey/migrate. |
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Suggest why an increase in temperature may causean increase in NPP. (2) |
*Therate of (bio)chemical/metabolic/photosynthetic reactions increases due to an *increasein movement/kinetic energy of enzyme/substrate/molecules; *thus increasing thereaction rate because of more enzyme substrate interaction/ collisions. |
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What is the unit J m–2 year–1 |
*The role/ purpose/ interaction of*an organism/ sea anemone/ species in a community; due to its *trophiclevel, i.e. if it is a *predator or *prey or provides a *shelter/ home for someanimals. |
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Succession is….. |
The sequence of changes to a community/organism over aperiod of time. |
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A climax community is…. |
the final stage/sere/community of succession, it is self-sustaining/ stable and has adominant species or a few co-dominant species. |
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Reproductively-isolated populations are….. |
where*no (inter)breeding between (the population) can take place *because of a(geographical/ physical) barrier. Physical barriers include the populationshaving *different mating behaviour, *incompatible genitalia and *eachpopulation having a discrete gene pool, e.g. restricted gene flow, differentmutation/alleles. |
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Describewhat might happen if deflected succession stops (i.e. forest clearing). (3) |
*Taller (growing) plantscould develop/ grow in the clear areas as they are no longer eaten, but therewill be *the loss of low-growing plants/ clear zones. *Different animals/species will appear as *secondary succession takes place where a *climaxcommunity of the taller plants is reached. |
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Suggest why/ how a community changes over time. |
*Lichens and mossesenter as the pioneer community;*they are able to grow in little/no soil and *will break up (rock) fragments,with their roots, to form thin/shallow soil *which is able to retain somewater/minerals. *Then short-rootedplants enter, they out compete the pioneer plant, *these are able togrow in shallow soil and in turn *will change the soil structure to enable trees/ shrubs to grow, *thesemay also out-compete the other species by interspecific competition for (a)biotic resources.*As the plants continue to lose leaves and die/decay they will *increase theamount of organicmatter/humus.: |
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Why is a climax community stable? (4) |
*A climax community iswhere (both) animals andplants are present/has many species/has high biodiversity; *there willbe interaction betweenthese species but they *will have reached a balanced equilibrium of species. *There may be a (co)dominantplant or animal species present.*This is stable as long as there’s no changeto the environment/human influence |
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A gene mutation is…. |
a changein DNA due to the change/deletion/addition/duplication/substitution bases/nucleotides. |
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Genetic diversity in a species is |
thevariety of alleles in a gene poo |
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A gene pool is.... |
The total of all the alleles in a population. |
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Allele Frequency is………. |
Theproportion of one allele within a gene pool/population |
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Explain why there is likely to be a greatergenetic diversity in a hybrid plant than in two separate species. (2) |
Becausethere are *different alleles in each of the two populations as *each population/species is adapted to living in different environmental conditions. *This meansthat there will be different mutations in each population. *In a hybrid the alleles of the twodifferent species will mix and hybrids will receive alleles from bothspecies |
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Suggest why scientists may classify organismsinto sub-species rather than two separate species. (2) |
*Ifthe organisms were allowed to interbreed and could *produce fertile and viableoffspring they could be considered as sub-species. *The hybrids/offspringcan flower and produce viable seeds. |
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Suggest how the two sub-species develop from asingle ancestral population, use boar |
Firsta *few ancestral boar reach the island/ habitat from their originalenvironment, there are now twopopulations that have *geographical separation perhaps by the sea orvolcanic eruptions. *These populations are unable to interbreed (reproductiveisolation) and so the *gene flow between the populations is restricted/prevented. *There are only a small number of boar, on the island (foundereffect), for breeding resulting in a *limited variety of alleles. *Mutations may then occur (*increasing diversity)that are *acted on by different environmental conditions/ selection pressures that areunique to the island (not found on mainland) ie food, habitat; the boar will *adapt to best suit these bynatural selection, *those with the mutation are more likely to survive andreproduce. These mutations will *changethe gene pool as they arise and possibly become more common, so the two are nowdifferent, *changing the allele frequency. *These changes will lead to phenotypic/ physiological/physical/behavioural changes; as a result* allopatric speciation may occur (can no longerinterbreed) |
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Explainhow the two different species of flower on an island may have evolved from asingle population of an ancestral species. (6) |
*The original population was increasing in size and spreadinginto a wider diversity ofhabitats where they were then *reproductively isolated, *i.e.diversity in flowering times,causing a *restriction of geneflow *between extremes of the population. Each habitat would havedifferent environmental factors and so different selection pressures. *Mutations may then havearisen (*causing a change in the allele frequency) and *other plant features so that the *plantsadapted to a specific region, advantageous features/mutations would allow theplants to *survive andreproduce, passing on new genes and creating *differences between gene pools. |
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Suggest how ecological isolation contributes to speciation. (2) |
*There may be differentconditions /environments in each region, i.e. a temperature difference, so*there will be different selectionpressures. The geographical isolation will mean that the two populationsare *reproductively isolatedfrom one another *causing a restricted gene flow/ separation of gene pools. |
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Suggest how genetic mutation may lead tospeciation (2) |
*This will give arise to different alleles/gene pool, leading to *new/different phenotypes. This new *allele/gene may beadvantageous, and so will be passed onto offspring; it could also be*disadvantageous. ) |
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Suggest why interbreeding does not take placebetween different populations of species. (3) |
Thesedifferent species are reproductively isolated, meaning that they may havedifferent *breeding times/ seasons, *courtshipbehaviour/rituals/displays/colour/songs. *Any offspring produced between thespecies may be infertile or not viable. |
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Suggest how a distinct species evolves fromanother species |
*Geographical isolation, e.g. aphysical barrier between the population occurs/allopatric speciation, thismeans there is *reproductiveisolation between the populations, *there is a restriction of gene flowbetween but not within the populations. *This creates two habitats that willcontain different selectionpressures *e.g. different food sources, or different habitats. *Mutations will have occurred,if they were advantageous they would have *helped the species to adapt to theconditions, *these alleles/genes would have been passed onto the offspring.This would have caused *a change in the gene pool e.g. increasing frequency of (mutation)alleles. |
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Suggest how the allele frequency for a plant eating mutation could change as a forest develops. (4) |
*Therewill be a change in frequency of either allele e.g. mutant increases/normal decreases *due to the reproductivesuccess of the mutant/non-photosynthetic individuals. *As the trees develop thepond will be more shaded this *(less light means) means less photosynthesispossible. *The photosynthetic individuals die/nonphotosynthetic individualssurvive and *pass on the mutation/allele for using organic compounds, *thusallowing more organic nutrients in pond. |
