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How DNA profiles are made from a small sample of DNA: 1. Get DNA sample from tissue, blood or semen as it will be easy to collect. 2. DNA must be cut into fragments using restriction endonucleases. 3. DNA fragments will underdo PCR alongside free nucleotides (Increase temperature to 90'C to break the hydrogen bonds between DNA strands, decrease temperature to 55'C to allow annealing of primers to the DNA strands, Increase temperature to 75'C as this is the optimum temperature for DNA polymerase to work as it will bind the free nucleotides to the DNA fragments. 4. This process must be repeated several times to get many copies of DNA (many or multiple are interchangeable here). 5. Put the DNA fragments into agarose wells. 6. Apply a potential difference from the negative electrode, causing the negatively charged DNA fragments to move towards the positive electrode. (Longer fragments of DNA will travel a shorter distance and shorter fragments of DNA will travel a longer distance). 7. This will produce a DNA profile with a series of bands which may differ in size and width. 8. Can be used to compare different peoples DNA and see if there is a genetic relationship between the two. How DNA profiles of two species are compared: Compare total number of bands, their position and width. How phagocytosis and lysosome action leads to APC by macrophages: Bacteria taken in my macrophage. Phagosome (vacuole formed around a particle absorbed by phagocytosis) fuses with lysosome. Enzyme e.g. protease from lysosome breaks down bacteria. Part of the bacteria is presented on macrophage’s cell surface membrane. How macrophages present antigens to T helper cells: Macrophage binds to T helper cell as the MHC on the macrophage binds to the CD4 receptor on the T helper cell. How evolutionary race between some bacteria affects antigen presentation to T helper cells: A mutation has occurred in the DNA of the bacteria. This has caused a change in the antigen of the bacteria. The memory T helper cells won’t recognise the new antigen. Thus a new primary immune response is needed e.g. new antigen needs to be presented to the T helper cell to activate another population of T helper cells. Two greenhouse gases are:

How DNA Profiles Are Made From a Small Sample of DNA

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How DNA Profiles Are Made From a Small Sample of DNAHow DNA Profiles Are Made From a Small Sample of DNAHow DNA Profiles Are Made From a Small Sample of DNAHow DNA Profiles Are Made From a Small Sample of DNAHow DNA Profiles Are Made From a Small Sample of DNAHow DNA Profiles Are Made From a Small Sample of DNAHow DNA Profiles Are Made From a Small Sample of DNA

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How DNA profiles are made from a small sample of DNA:1. Get DNA sample from tissue, blood or semen as it will be easy to collect.2. DNA must be cut into fragments using restriction endonucleases.3. DNA fragments will underdo PCR alongside free nucleotides (Increase temperature to 90'C to break the hydrogen bonds between DNA strands, decrease temperature to 55'C to allow annealing of primers to the DNA strands, Increase temperature to 75'C as this is the optimum temperature for DNA polymerase to work as it will bind the free nucleotides to the DNA fragments.4. This process must be repeated several times to get many copies of DNA (many or multiple are interchangeable here).5. Put the DNA fragments into agarose wells.6. Apply a potential difference from the negative electrode, causing the negatively charged DNA fragments to move towards the positive electrode. (Longer fragments of DNA will travel a shorter distance and shorter fragments of DNA will travel a longer distance).7. This will produce a DNA profile with a series of bands which may differ in size and width.8. Can be used to compare different peoples DNA and see if there is a genetic relationship between the two.

How DNA profiles of two species are compared: Compare total number of bands, their position and width.

How phagocytosis and lysosome action leads to APC by macrophages: Bacteria taken in my macrophage. Phagosome (vacuole formed around a particle absorbed by phagocytosis) fuses with lysosome. Enzyme e.g. protease from lysosome breaks down bacteria. Part of the bacteria is presented on macrophages cell surface membrane.

How macrophages present antigens to T helper cells: Macrophage binds to T helper cell as the MHC on the macrophage binds to the CD4 receptor on the T helper cell.

How evolutionary race between some bacteria affects antigen presentation to T helper cells: A mutation has occurred in the DNA of the bacteria. This has caused a change in the antigen of the bacteria. The memory T helper cells wont recognise the new antigen. Thus a new primary immune response is needed e.g. new antigen needs to be presented to the T helper cell to activate another population of T helper cells.

Two greenhouse gases are: Carbon dioxide. Methane.

First generation biofuels could reduce global warming instead of petrol/diesel because: Burning fossil fuels releases carbon dioxide which is a greenhouse gas. Carbon dioxide is taken in for photosynthesis for carbon fixation during the production of plants for biofuels thus there is no net change of carbon dioxide in the atmosphere when biofuels are burnt. Biofuels are carbon neutral!

Why cellulose has to be treated with enzymes before bacteria can use it as an energy source: Bacteria cannot breakdown cellulose fast enough so enzymes like cellulase are needed to break down cellulose into beta glucose by hydrolysing 1,4 glycosidic bonds.

The changes in distribution of organisms after glaciers disappear are: As time increases, the biodiversity of organisms increases. Primary succession occurs whereby pioneer species such as lichens are the first organisms to colonise bare rock. These pioneers improve the conditions for plants by changing rock into soil. There will be competition, limiting the species currently present e.g. newer species outcompete previous species.

What a niche is: The role of an organism within its ecosystem. The specie the question is talking about is a producer (because its a plant) and so it provides food for other organisms. It also improves the soil e.g. holds soil structure together. It provides shelter for organisms.

How to carry out a study of the distribution of X: Use transect from ____. Sample along the transect using a quadrat. These sample sites along the transect are selected using systematic sampling. Estimate abundance e.g. through number of plants.

One abiotic factor that affects the abundance of the plant and how it can be measured: Light affects it Can be measured using light probe and reading should be taken at the height of the plant. Take several readings and get an average.

Effect of temperature on decomposition (of leaves): Increase in temperature would increase rate of decomposition up to an optimum temperature. Enzymes are used in decomposition. Increased heat results in an increase in the number of collision between enzymes and substrates thus increase rate of reaction. Above a certain temperature, the rate of decomposition would decrease as enzymes become denatured.

The role of RUBISCO in the production of GALP in the light-independent reaction is: RUBISCO is an enzyme in the Calvin cycle. Its involved in carbon fixation to form GP. GP is converted into GALP using ATP and reduced NADP.

How the membranes inside the chloroplast are involved in photosynthesis: Thylakoid membranes are the site of light-dependent reactions. Has chlorophyll, electron carrier proteins etc. within its membrane. Also has ATPase in it. Provides space for the accumulation of protons.

Structure of enzymes: Globular proteins with active site. Has charged R groups on the outside that are hydrophilic.

How anti-viral drugs would work in people w/ HIV: Drugs would prevent viral replication. T helper cells wouldnt be killed by the virus particles leaving the cell. Inhibits reverse transcriptase so that viral DNA cant be made from viral RNA. Inhibits integrase so that viral DNA cannot integrate into host genome.

Division that occurs when T helper cell is cloned: Mitosis.

How a microscope slide could be prepared to observe cell division in T helper cells: Make a slide of T cells from the blood. Use a stain like acetic orcein. Heat stain using acid. Look at mitotic features.

The role of T helper cells in the immune response: Cytokines from T helper cells stimulate B cells. B effector cells differentiate into plasma cells that produce antibodies. Also activate T killer cells that destroy infected host cells.

How is Golgi apparatus involved in T helper cells: It packages proteins like cytokines, CD4 receptors etc. These synthesised proteins then leave by exocytosis.

Judging reliability by looking at graph: Long error bars indicate low reliability. Overlapping error bars are less reliable.

Why antibiotics cannot be used to treat infections caused by viruses: Viruses are non-living and have no target sites for antibiotics.

Two ways hospitals can reduce spread of infections caused by viruses include: Use hand washes. Reduce proximity of patients to each other (i.e. isolate them!).

NPP is: Rate of production of energy incorporated into biomass. NPP = GPP R in producers.

The relationship between NPP and rainfall and temperature:Temperature: NPP depends on photosynthesis; the higher the temp the more NPP. Enzymes in photosynthesis can works faster so more enzyme-substrates are formed.Rainfall: Increase in rainfall increases NPP. Water is needed for light-dependent reaction as it transports mineral ions/amino acids/sucrose.

Two structures that would classify an organism as eukaryotic: Chloroplast. Nucleus.

How a colony of genetically identical cells could develop from a single original cell: Mitosis. Followed by cytokinesis. Repeated several times.

Why the following are important in production of carbohydrates in photosynthetic cells:Thin lamina: Maximum gas exchange so more carbon dioxide is used in Calvin cycle.

Vessels in midrib: Transport in xylem of water to leaves; water for light-dependent reactions for photolysis as a source of hydrogen ions Transport in phloem of sucrose away from leaves.

How GALP formed can be used to synthesise the cellulose in plant cell walls: GALP converts to glucose, which is beta glucose. Glycosidic bonds forms between carbon 1 and carbon 4 by condensation. This forms straight chains of glucose.

Production of biofuels isnt carbon neutral because: Carbon neutral means that carbon dioxide produced = carbon dioxide used. Forests act as carbon sinks. Deforestation results in net increase in carbon dioxide in the atmosphere. Less plants means less carbon dioxide is removed by photosynthesis. Burning trees can produce carbon dioxide. Increased decomposition produces carbon dioxide. Using fossil fuels by lorries/machinery to clear the land produces carbon dioxide.

How combustion products from burning fuels may lead to global warming: It produces a greenhouse such as carbon dioxide. These gases build up in the upper atmosphere. They absorb infrared radiation reflected from earths surface. Increased levels of these gases increases greenhouse effect so mean temperature of earths surface increases.

GPP = 10400; efficiency of grassland is 45%; calculate NPP and R: NPP = 0.45x10400 = 4680. 10400-4680 = R.

Relationship between GPP and NPP: NPP = GPP R 55% of GPP energy is lost as heat to provide for active transport. NPP is stored energy.

NPP values would be useful for a farmer who wants to use his land for cattle because: Cattle are primary consumers therefore gain energy available as NPP. So itll affect yield of meat/milk so changing to a more NPP yielding crop may be useful.

Triplet code means: Each amino acid is coded for by three bases e.g. 12 bases code for 4 amino acids.

Non-overlapping code means: That each triplet is discrete as each base is only used once in a triplet e.g. AAT AAC CAG TTT give 4 distinct triplets.

Degenerate means: That more than one code can be used for a particular amino acid e.g. stop code e.g. both AAT and AAC code for leucine.

How translation of mRNA synthesises part of a polypeptide molecule (i.e. transcription): Refer to the mRNA sequence of the question. Ribosome is involved. Each tRNA molecule is attached to a specific amino acid. Anticodons on tRNA bind to codons on mRNA and hydrogen bonds between the bases of mRNA and tRNA form. Peptide bonds form between adjacent amino acids.

Two differences between genetic material of bacteria and viruses: Bacteria have DNA, viruses can have DNA/RNA. Bacteria have circular genetic material, viruses has linear genetic material.

How macrophages ingest bacteria: Phagocytosis i.e. formation of pseudopodia around bacteria to engulf it. Bacterium inside vacuole.

Why treatment with antibiotics may not be effective against dormant bacteria in tubercles: Bacteria are inside macrophages and has waxy layer. Also may be resistant to these antibiotics.

How artificial active immunity develops following a vaccination: Attenuated pathogens are put into the person, which stimulates an immune response. T helper cell activates e.g. macrophages become APCs as they engulf antigen by endocytosis. B cells activated as B cells become APCs and cytokines from T helper cells stimulates. T killer cells activate as they attack infected cells with APC and are stimulated by cytokines. Memory cells produce.

Why activity of bacteria e.g. TB and inhibition of T cells can lead to death: Further lung damage and severe breathing problems e.g. cannot obtain enough oxygen. Mycobacterium gets into blood/lump leading to organ failure that leads to death. Reduced immune response due to loss of T cells. So no T helper cells that produce cytokines, no T killer cells so infected cells wont be destroyed and no B cells so no antibodies produced. Thus opportunistic infections can arise and cause death.

Why viruses cant infect cells if they land on unbroken skin: Skin is a barrier made out of keratin. There are also no receptors for the virus.

Why a common cold virus cannot infect cells if they enter blood through a cut in the skin: The virus only attached to specific receptors that arent present on blood cells.

Why species dont interbreed: Reproductive isolation. Different breeding times. Dont recognise courtship displays. Physically incompatible e.g. different genitalia.

Why the rate of change in the appearance of species can be slow: They share the same habitat so they experience the same environmental conditions. Thus will have the same section pressures. Also, both are well adapted to their environment so no mutations may have occurred that improve their survival. Thus few changes in allele frequency and gene pool remain stable. Also theres very little change to an environment over time.

Why reproducing asexually and sexually is advantageous to lichens: Advantage of sexual reproduction is greater gene pool. Advantage of asexual reproduction is conserves advantageous alleles.

How percentage cover of a species can be determined: Use quadrat Systematic sampling of the area. Count number of squares containing the species.

How light intensity can be measured at the surface of something: Use light probe and take several measurements.

How whatever data collected could be used to show a relationship: Plot a scatter graph of Y against X. Look for a correlation Use a statistics test e.g. Spearmans rank.

How GP can be used to synthesise starch: GP converts to GALP using ATP and reduced NADP. GALP converts to glucose which is an alpha glucose. Glycosidic bonds form by condensation; these bonds are 1-4 and 1-6 glycosidic bonds. Amylose and amylopectin are a part of starch; amylose is straight chain and has 1-4 bonds whereas amylopectin is branched and has both 1-4 and 1-6 bonds.

How forest fires can lead to global warming: Fire produces carbon dioxide which is a greenhouse gas. These gases form a layer in the upper atmosphere and absorb infrared radiation reflected form Earth. This increases mean temperature of surface area of earth. Less carbon dioxide is removed by photosynthesis as the trees are GONE.

Biofuels are good because: They are possibly carbon neutral. Plants are used for biofuels. Carbon dioxide is used by the plants that are needed in biofuel production. Thus using biofuels can replace fossil fuel use.

GPP means: Rate of energy incorporated into biomass in plants.

Why NPP is less than GPP: Energy is lost as heat by respiration.

Advantage for why most amino acids have more than one code: Effects of mutations are reduced. Third base can be altered with no effect on the resulting polypeptide.

Stop codons: Stop codons occur at the end of the gene on a DNA and are transcribed as mRNA. Theyll be recognised by ribosome and they signal end of the polypeptide during translation.

How amino acids are joined together in a polypeptide: Peptide bonds between amine group and carboxyl group in a condensation reaction.

How antibodies help a person recover: Antibodies bind to bacteria and enhance phagocytosis as a result as they immobilise bacteria.

Species: Organism that can interbreed to produce fertile offspring.

Characteristic features of antibodies: Y shape of 4 peptide chains with disulphide bridges between peptides. Produced by plasma cells. Is a glycoprotein.

How scientists can develop a means of producing active immunity to HIV infection: Artificial active immunity through vaccination containing synthetic antigen. Humoral immune response to synthetic antigen. Process of producing effector B cells e.g. clonal expansion of B cells through cytokines released by T helper cells.

Why data about HIV infections are often estimates: HIV infection doesnt always produce symptoms. Test is needed to detect HIV and only those suspect of having it would have a test.

Chemical reaction involved in digestion of cellulose by enzymes: Hydrolysis.

Likely product of digestion of cellulose by bacteria: Glucose.

What would happen if number of animals in a clear area in forests decreased: Taller growing plants could develop in the clear areas. Loss of clear zones. Different animals appear.

Reproductively-isolated populations are: No interbreeding between species due to a geographical barrier. Different behaviours and incompatible genitalia. Each population has a discrete gene pool e.g. restricted gene flow, different mutations, different alleles

How forensic entomology is used: Body dead for a while because more than one species of insect is present. Succession of insect species. Life cycle times of insects are used which depend on temp.

How body temperature could determine time of death: Drop in body temp is linked to time after death. Factors affecting temperature drop e.g. ambient temperature, body size, clothing. Useful because time of death can be calculated if ambient temperature is known. Only useful for short period of time following a day e.g. 24h

How state of decomposition could determine time of death: Body decomposes in a specific sequence with time. Factors affecting decomposition e.g. wounds. Not useful if entire body had decomposed.

Why DNA can be described as a double-stranded polynucleotide: Because made of two strands that are joined by hydrogen bonds between bases. Polynucleotides of many nucleotides linked by phosphodiester bonds.DNA ProfilingPolymerase is the. enzyme used in the Polymerase Chain Reaction to amplify DNA in a small sample of blood taken from a crime scene.

Gel Electrophoresis is the process used to separate DNA fragments to create a DNA profile

Describe how gel electrophoresis can be used to analyse DNA. (3) *First, a DNA sample will be collected from blood, saliva or semen etc; *these small samples of DNA can then be amplified by PCR. DNA profiling then takes place which uses *restriction enzymes to break the DNA and then *uses electro potential difference, with the DNA in a gel, to draw the bands apart. *The DNA is stained so it can be seen and will *show up as bands/bars. *The number of bands that match indicates the similarity of the DNA.

Name substances X, Y and Z:Substance X ...........DNA PrimersSubstance Y......... (mono)nucleotidesSubstance Z ..........DNA Strands

What are the temperatures for?T1: Heated to 9095 CT2: Cooled to 5560 CT3: Heated to 75 C

Using DNA profiling explain how a suspect is found guilty. (5)A DNA match is needed, this means that *all of the bands in the sample are the same as the ones shown in the evidence sample. *DNA profiling assumes every individuals DNA is unique/different; *apart from identical twins. *DNA profiling analyses the introns/noncoding blocks/STR parts of DNA as the *non-coding areas are hypervariable because *there are a large number of introns/non-coding blocks and so there can be *many combinations of STRs at each locus.

Suggest how DNA profiling could be useful to scientists who examine fossils of animals and plants. (2)*Comparisons could be made between DNA from fossils and other organisms *to find genetic relationships/how closely related they are. It may also be *used in taxonomy/classification *to understand evolutionary lines/to determine a common ancestor.

Explain how the results of DNA profiling of tissue samples from the two sub-species could be used to provide evidence that they share common ancestry. (3) DNA profiling will *produce bands that will have spread to *certain positions. *Common/similar bands will contain similar DNA fragments; *the more similar these patterns, the closer the relationship/more likely the sub-species will have a recent common ancestor. *There will still be very few differences between the DNA of sub-species.

Suggest how DNA analysis could give further evidence for evolution. (2)DNA analysis could show the *similarity (of DNA) and indicate the closeness of a genetic relationship *because genes are sections of DNA and these *genes are the codes for proteins.

Why cant species of plants be identified from woody (xylem) material using PCR and DNA profiling? (2) Because *xylem/wood is made of dead material/has no living material/cytoplasm/nuclei/ mitochondria, meaning *no DNA / nucleic acid is present in the material.

Suggest why DNA polymerase from human sources is not suitable for use in a PCR machine. (2)*Because human enzymes will not work at high/ above 37oC temperatures due to *denaturation (change in shape of active site) at the temperatures found in the PCR (55-95C).Explain why evidence from DNA profiles may not be absolutely conclusive. (2)*DNA profiling has several stages and *artefacts/contamination can arise at any stage. Furthermore as *only a few sequences/a small portion of DNA is analysed it is *possible to get two identical profiles from unrelated individuals or for *identical twins/closely-related individuals to show the same profile. Thus the minimum amount to be analysed is 10STRs Decomposition and forensicsThe first stage in the decomposition of a cow pat is known as putrefaction. Explain how carbon dioxide and ammonia are formed during this stage of decomposition. (4) *Microorganisms/microbes/bacteria/fungi are decomposers that *convert organic compounds to carbon dioxide and *nitrogen compounds/proteins/amino acids/urea to ammonia. *Aerobic/ anaerobic respiration *of the microorganisms/bacteria/fungi is the process whereby this occurs.

Suggest why the time taken for a cow pat to decompose changes at different times of the year. (3) *Because in the warmer times of the year the process will be faster as more heat energy is available and so kinetic energy is available for enzyme reactions/ to speed up the metabolism but less is available in the winter months (temperature effect). *There will also need to be sufficient water availability for the microorganisms to survive (*e.g. If frozen it cannot be accessed) however *too much water can lead to waterlogging which reduces oxygen availability and thus the amount of energy produced for decomposition.There may also be *more insects/decomposers in summer. The *rate at which the microorganisms grow will also be a factor as it depends on how much food is available and how long they will be there to decompose the pat.

Suggest how woodlice are involved in the recycling of carbon. (3) *The carbon/organic compounds in plant material are broken down in *digestion to provide respiratory substrates, *carbon dioxide is then released from them in respiration. *This carbon dioxide is available for photosynthesis. The carbon consumed may also become a part of the woodlices biomass until it is eaten or dies and decomposes to release it.

Describe the role of microorganisms in the recycling of the carbon from compounds in a dead animal. (3) Decomposition/putrefaction occurs by microorganisms, they may digest the carbon in the animal and then release the carbon into the atmosphere by *respiration where the *carbon dioxide is used for photosynthesis. *Methane is released in anaerobic conditions and is *available as fuel.

Suggest three factors that could influence the rate at which a body cools after death. (3)*(Body) mass/ BMI / weight; *(subcutaneous) fat; *surface area; *ambient temperature, *immersion in water; *age (of person at death); *skin colour; *thickness of hair; *gender; *clothing; *blood loss; *humidity; *air movement; *{core / body} temperature at time of death.

Suggest two environmental factors that influence the rate of progress of rigor mortis in a muscle immediately after death. (2) *Physical damage; *immersion in water; *(external) temperature; *burning; *electrocution; *clothing; *wind/air movements; *(Presence of drugs in the body: bio)

Suggest why a forensic scientist would need to consider rigor mortis in several muscles of a body when estimating the time of death. (4) Because *not all muscles will contract/relax/reach (full) rigor mortis at the same time; *e.g. jaw muscle will contract fully before the leg muscle. *Full contraction/rigor in muscle does not last very long; for example the *leg is still contracting while jaw is relaxing.

Suggest how the time of death of a white rhinoceros could be determined if it is discovered several days after being killed. (5) You could work out the time of death by looking at the *stage of succession on the body (if it has been a long period of time). You could also use *(forensic) entomology which involves identifying *the life cycle stages/ species of insect on the body *e.g. fly, beetle, wasp. You could also work out the time of death by looking at the *decomposition of the body as there are *different stages of decomposition. Decomposition involves *putrefaction (discolouration of abdomen that spreads), liquefaction of tissue, bloating and production of gases.*All of this information (insects, succession etc) is used to determine time of death, each of these methods conclusions are *influenced by an external factor such as temperature that influences the rate of succession/insect development/ decomposition.

Suggest how Body Temperature would be useful in determining the time of death (2)*A drop in body temperature is linked to the amount of time that has passed after death e.g. algor mortis, *many factors affect the temperature drop e.g. environmental temperature, body size, clothing. It is useful because *time of death can be calculated if the (ambient) temperature is known however it is *only useful for a short period of time following death e.g. 24 hours/a day.

Suggest how the state of decomposition would be useful in determining the time of death (2)Because the *body decomposes in a specific sequence over time it can be useful in determining time after death but *many factors affect the rate of decomposition e.g. environmental temperature or the presence of wounds. It will also *not be useful if all the body has decomposed.Protein SynthesisStatement True False? (3)AACTAGT TGGCAAGTGGTCACThis sequence of bases could be used as a template during translation FA strand of mRNA could be synthesised using this sequence TThis sequence codes for 7 amino acids during protein synthesis T

Thymine cant be found in.. mRNAA cistron is..the sequence of triplets on a section of DNA used to form a strand of pre-mRNA A Peptide Bond.. links the amino acids in the primary structure of a proteinReverse transcriptase is the enzyme is used to produce DNA from viral RNA in an infected cell Transcription takes place In the nucleusThe amino acids in a primary structure are linked together in the ........RibosomeNucleotide is the.term used to describe each of the sub-units in a molecule of RNAName and describe the structures where the polypeptide chain of an enzyme would be synthesised. (2) The polypeptide chain would be synthesised on the *ribosomes attached to the membrane of the rough endoplasmic reticulum. *The ribosomes consist of rRNA and are a protein component of two sub-units/ a large and small sub-unit.

Explain why a molecule of DNA can be described as a double-stranded polynucleotide. (3) *It is double-stranded because it is made of two strands *joined by hydrogen bonds between the bases and it is *a polynucleotide of many nucleotides that are *linked by phosphodiester bonds.

Explain how pre-mRNA is formed during transcription in the nucleus. (3) First the *DNA strands separate/unzip by the use of *DNA helicase, *one DNA strand of 12bases is used as a template (to form mRNA) *from free nucleotides via complementary base pairing and the formation of hydrogen bonds between the bases. RNA-polymerase catalyses the transcription process.

Describe how free nucleotides are bonded together in the correct sequence in the formation of pre-mRNA. (3)*The sequence of bases/nucleotides on DNA determines the sequence on (pre-)mRNA, the codons will *bond in complementary base pairs (give example eg. GTA= CAU) by the formation of *phosphodiester bonds in *condensation reactions. This process is catalysed by *RNA-Polymerase.

Explain how the translation of mRNA into the sequence of amino acids in a ribosome occurs. (3) *A specific amino acid is attached to tRNA (coded for by the anticodon). *The anticodon on tRNA binds to the codon/triplet on the mRNA strand, only two tRNA molecules are held in the ribosome at any one time. When a third tRNA comes along the first tRNA detaches, after the *peptide bonds have formed between the adjacent amino acids. *Peptidyl transferase catalyses this process.

Suggest why the final triplet of nucleotides, on a strand of mRNA involved in the synthesis of a sequence of amino acids, did not correspond with any anticodon on tRNA. (2)Because it was a *stop codon and is *used to end the sequencing/further attachment of tRNA and signal the *release of the polypeptide from the ribosome.

Explain the function of the codons at each end of a strand of mRNA, during the process of translation. (2) *They function as start/stop/nonsense codons. The *start (codon) is needed to begin the Polypeptide/protein synthesis and *the stop/nonsense (codon) is needed to end polypeptide synthesis.

Suggest why a variety of different protein structures could be formed from the polypeptides synthesised using the mRNA molecules from a single gene. (3) *Because there are many variations of exons/mRNA which lead to *different primary structures of a protein/sequence of amino acids. The *secondary and tertiary structure of the proteins depends on the primary structure. There will also be a variety because there are *different bonds, some are hydrogen/ionic/disulphide bonds, the proteins formed will also have *different 3D shapes.

Describe how the sequence of bases in a DNA molecule would be used to form the primary structure of a protein. (5)*The sequence of bases forming the genetic code determines the amino acid sequence as *one triplet codes for an amino acid. *The DNA acts as a template during transcription (e.g. DNA unzips by helicase and mRNA is synthesised).*Post-transcriptional modification of mRNA then occurs where introns (non-coding regions of DNA) are removed by splicing using the enzyme spliceosome, leaving only exons behind in the mRNA to join back together. After modification the *mRNA moves from nucleus to the cytoplasm through a pore in the nuclear membrane, so that *translation may occur on the ribosomes found attached to the rER (ribosomes aid codon-anticodon interaction). *tRNA then carries an amino acid to the ribosome and joins with its complementary base pair, *forming peptide bonds between the amino acids forming the primary structure of a protein this is the sequence/order of amino acids specified in DNA.

Non-Specific Immune ResponseInterferon is the enzyme released in secretions that interferes with protein synthesis of viruses.

Histamine is the.chemical released by white cells in connective tissue that causes swelling

D = antigens / (glyco)proteins ;E = B {lymphocytes / cells} / plasma cells ;F = antibodies / immunoglobulins ;G = macrophage / phagocyte / eq ;H = enzymes / lysozyme ;

Explain why the processes shown in the flow diagram will only happen in response to some types of bacteria. (3) Because the protein nature of antigens/antibodies is different, the *antigens are specific to each bacteria strain and the *antibodies need to be complementary/specific to the antigen so that binding can take place. *Some bacteria will have different/changed antigens to another, they may also have different *slime/mucus capsules or be *inside body cells, this changes the effectiveness of the antibodies. This is also a *primary infection meaning some antibodies are already present from passive immunity or breast feeding.

Describe how the production and action of interferon differs from the production and action of lysozyme. (3) *Interferon is involved in viral infections, whereas lysozyme affects bacteria only. *Interferon is produced only by infected cells, but lysozyme is present in all secretions (i.e. saliva/phagocytes/neutrophils/macrophages. They have different roles, *interferon inhibits replication of viruses and lysozyme kills/ destroys bacteria.

Suggest why the protein structure of lysozyme is important to the way in which it acts against pathogens. (4)*lysozyme is an enzyme and so it *has an active site with a specific shape for binding with our cell membranes. *The lysozyme acts on the cell wall *of bacteria so that cell lysis occurs.

Explain why an insect bite, which breaks the surface of the skin, may lead to inflammation around the injury. (3)Because *histamine is released as a result of damaged tissue/cells, *it is released from mast cells/platelets. *Histamine causes the arterioles to dilate (vasodilation), which increases blood flow and makes the capillaries more permeable allowing phagocytes to reach the site more easily. *Inflammation involves oedema/swelling/redness/heat/pain at the site of injury.

In order to reduce inflammation, a cream containing antihistamines might be applied to the skin, around an insect bite. Suggest why applying this cream might be better than taking tablets containing antihistamines. (3)Because inflammation is *only a local reaction produced/that histamines produced around the bite area and so *cream that has been applied to actual site of production of histamine *will be more effective and have more rapid/ immediate relief as it will create a *higher concentration of antihistamine at the site. *The antihistamines will not be digested (by enzymes)/destroyed (by acid or enzymes) if they are applied in a cream and not tablet. The *tablets may lower the immune response generally/lead to unpleasant side-effects.Specific Immune Response

Natural passive Artificial passive Natural active Artificial active

When MRSA enters the blood it can stimulate the production of several different clones of plasma cells. These produce a variety of antibodies (polyclonal antibodies). Suggest an explanation for this. (4) Because the *bacterium is made of many different polymers/chemicals *which can act as different antigens, *individual B-lymphocytes will recognise specific antigens/antibodies are specific and so only certain *B-lymphocytes are activated by T-lymphocytes. These cells of *B-lymphocytes will then divide by mitosis *to form genetically identical plasma cells that secrete specific antibodies.

Suggest the advantage of using monoclonal antibodies, rather than polyclonal antibodies, in the detection of antigens in the blood. (3)Because a *specific antigen/virus/pathogen/bacterium can be identified as the *specific/ monoclonal antibody binds to a specific antigen. As a result *specific treatment can be given that will *avoid unnecessary use of drugs/treatment and will be *more likely to be effective.

State two characteristic features of antibodies. (2)*They have glycoproteins in their cell walls; have a *specific (3D) shape, L and H regions, Y-shape, 4 (peptide) chains, disulphide bridges between peptides, hinge region; they also *have an antigen-binding site/variable region; all antibodies *have a similar/constant region; they are *produced by plasma cells/present on B cells; *their role is opsonisation, immobilisation, agglutination, lysis of foreign cells.AntibioticsBactericidal antibiotics is the name of antibiotics, such as vancomycin, that kill bacterial cells

The epidermis is. a part of the skin that forms a physical barrier against infection by pathogenic bacteria

What are bactericidal antibiotics? Antibiotics that kill/destroy bacteria cells by weakening their cell walls so their cells burst Ignore reference to stopping growth

Suggest how bacterial cells are killed by vancomycin (antibiotic). (2) The antibiotic may *weaken the bacteriums cell wall or not allow it to form properly *so the cell bursts easily, perhaps *during division.

What are bacteriostatic antibiotics?Antibiotics that stop cells from increasing in number/replicating by preventing cell division.

Explain what is meant by the terms bacteriostatic antibiotic and bactericidal antibiotic. (3) *An antibiotic is used to control/kill/prevent reproduction of bacteria. *Bacteriostatic antibiotics will prevent the reproduction/division/multiplication/growth of bacteria whereas *bactericidal antibiotics will destroy/kill the bacteria.

Suggest why antibiotics may be used as part of the treatment for influenza. (2) Because *influenza may allow the development of other diseases e.g. opportunistic infections and *the antibiotics will kill/inhibit growth of these bacteria.

Suggest why health authorities in the USA are encouraging the reduction in the number of prescriptions of antibiotics. (2)Because *some bacteria are resistant to the antibiotics and this *resistance is genetic and can be passed on. *MRSA, for example is already resistant to many antibiotics.

Explain why doctors have been advised to limit the prescription of antibiotics. (2)Because *antibiotics act as a selective pressure, *some bacteria are already resistant to some antibiotics. These *resistant bacteria survive and pass on the resistance gene so that the antibiotic is no longer effective. *Some infections cannot be treated with antibiotics (ie viral infections)

Describe how you could investigate the effect of different antibiotics on bacteria. (4)*Bacteria could be distributed evenly by lawn spreading, *multidisks or wells in the agar may then be placed at known positions to see the effectiveness of the antibiotic. The *same concentration of antibiotics must be used and the petri dish must be set using a sterile/aseptic technique/conditions. The dish must then be kept *incubated at a suitable temperature (below 30C to prevent the growth of pathogens) and *the lid of the petri dish not all the way fastened to prevent the growth of anaerobic bacteria. You can measure the effectiveness by measuring the clear area/inhibition zone around the antibiotic area. The investigation should be *repeated with both the same conditions and bacteria and *different bacteria to asses overall effectiveness.

Suggest why medications, other than antibiotics, are needed to treat the most severe cases of BRD (viral infection). (2) Because the infection *involves both viruses (and bacteria via opportunistic infections), and (usually) antibiotics are only effective against bacteria/do not affect viruses. Thus *other medication will be needed to deal with viruses.

Suggest why it might be advisable to change the antibiotic being used, in the treatment of (cattle), once a pathogen has been identified. (3)Because the specified *antibiotic used is the most effective against the now known bacterium. *None of the antibiotics are 100% effective/some bacteria may survive or *be resistant or a *resistant strain may develop/be prevented by changing the antibiotic.

Suggest how the constitution of blood may change if an ill person is treated with antibiotic drugs. (2) There will be *fewer lymphocytes as *the lymphocytes are no longer needed as the *antibiotics have killed/destroyed the bacteria.

Or: There are *more lymphocytes as there has been a *clonal expansion of lymphocytes because the *antibiotics have not killed all the bacteria yet.

Suggest how the constitution of blood may change if an ill person is given a placebo. (2) *A placebo has no effect on the bacteria *so there will be more bacteria, and *thus more lymphocytes due to *clonal expansion.Vaccinations and prevention. Suggest how scientists may be able to develop a means of producing active immunity to HIV infection using synthetic HIV antigens. (5)*This will be a method of *artificial (active) immunity, perhaps by using a *vaccine/vaccination *containing the synthetic molecule/(synthetic) antigen/(synthetic) glycoprotein. *A specific/humoral immune response to the synthetic antigen will be stimulated, i.e. *Effector B cells will be produced by clonal expansion of B cells, involving cytokines or T helper cells will activate B cells. These will then *produce B memory cells that will cause (2G12) antibodies to be produced faster/in greater concentration on reinfection (secondary immune response).

Describe how a vaccine gives active immunity against PWMS. (3) *You may use the virus as a vaccine, *which will contain a modified/attenuated/ harmless/similar form of the virus that *contains the virus antigen. The vaccine will stimulate the *activation of (specific) B cell/T cell/lymphocytes and cause the *production of B/T memory cells; this means that the *body is now able to produce (specific) antibodies faster/at higher concentration on another exposure to the virus.

State two ways in which the skin flora can help to protect a person from infection by pathogenic bacteria. (2) *They provide interspecific competition for nutrients and *for space. They also *secrete chemicals/substances/lysozyme OR affects pH so the pathogenic bacteria cannot survive there. They also *stimulate the (skin) immune system.

Suggest why the rate of MRSA infection in different hospitals differs. (3)*One hospital may have stricter hygiene practices such as strict *hand washing regimes for doctors/nurses/medical staff/visitors *particularly when dealing with open wounds. *The nurses may also have to wear suitable clothing such as no ties or long sleeves or have *antiseptic (solutions) readily available such as *gels, pastes, alcohol rubs. Patients may also be *isolated if they are a suspected cases of MRSA or screening of admissions to ensure they are clean. Better hospitals may also monitors the use of antibiotics or have *fewer patients/visitors passing in and out.

In a study in a London hospital, it was found that pillows contaminated with bacteria could spread infections between patients. Suggest how this hospital could improve the prevention and control of the spread of infections. (3)*Hospitals will have to change a code of practice/protocol/policy/standards currently present for dealing with hospital acquired infections. They may introduce *clothing rules for hospital workers such as no long sleeves or jewellery (reduces places pathogens can hide); they may also *improve laundry services of bed linen e.g. increased washing frequency/higher washing temperature. They may also *use special pillow cases/treat the pillow cases e.g. microfilters, treated with antibacterials,sterilisation, disposable pillow cases or they could *use special procedures when carrying pillow cases/bed linen to the laundry e.g. sealed plastic bags to prevent it spreading to the workers. *Screening of patients/isolation of infected patients could help as the infected can be isolated to reduce the spread of infection. *Hand washing regimes before and after seeing patients could also reduce the spread.HIV

Name two types of cell that HIV enters in the immune system.*T helper/CD4 positive cell/lymphocytes; *phagocytic cells e.g. macrophages, dendritic cell

State how the genetic material in HIV differs from the genetic material in the Mycobacterium tuberculosis that causes TB. (2)*RNA is found in HIV/ virus and DNA in the bacterium/TB, *the nucleic acid in the bacterium is circular whereas it is linear in HIV. *There are also plasmids in bacterium and no plasmids in HIV.

One of the ways in which HIV may enter the blood is through the use of infected needles. Explain why unbroken skin is an effective barrier against HIV infection. (2) *Keratin/protein in skin surface/epidermis *forms a physical/impenetrable barrier to HIV.

Suggest one effect that HIV causing T killer cells to destroy T helper cells will have on one other component of the infected persons blood. (1)*B cells/lymphocytes not activated resulting in fewer antibodies and *T killer cells increasing due to demand for use.

Describe the change in numbers of CD4 T-lymphocytes during the first 6 weeks after infection with HIV. (2) *Overall numbers will decrease. *There will be a small decrease in the first week/between weeks 4-6; *however the decrease is greatest between weeks 1-3

Explain the change in numbers of CD4 T-lymphocytes during the first 6 weeks after infection with HIV. (5)*The glycoprotein/gp120 on the virus *binds with receptors/CD4 *on (surface) membrane of lymphocytes, the *viral RNA then enters the lymphocyte. Once inside the *viral RNA is used to produce viral DNA (in the lymphocyte) *by action of reverse transcriptase *allowing the formation of new viruses. The *lymphocyte is then destroyed when new viruses bud out of/leave the cell. The *T killer cells then destroy the infected T helper cells/lymphocytes.

How is HIV able to enter the immune systems cells? (3)*First, the HIV binds to (CD4) receptors on cell surface membrane (CD4 receptors are found on the lymphocytes) *using the gp120/glycoproteins on the virus surface. *The virus envelope then fuses with the hosts cell surface membrane allowing viral RNA to enter the host cell. *Macrophages also have CD4 receptors and may be infected in phagocytosis.

Describe the sequence of events following infection by HIV, which may lead to the death of the patient. (6) The HIVs *viral RNA is used in reverse transcription using the enzyme, *reverse transcriptase, to *produce viral DNA using viral RNA as a copy. *The viral DNA is then incorporated into the host cells DNA/genome by the use of the enzyme *integrase. The hosts DNA can now be used in the *production of more viruses/viral RNA and proteins, these virus molecules may then bud out of the cell to *infect further (T helper) cells and destroy the recent host cell by *cell lysis. *THelper cells are needed in the immune response to produce cytokines, activate B cells/ killer cells. *Meanwhile there is destruction of infected (T helper) cells by T killer cells, which also contributes to *lowering the immunity to other diseases. *Death may be caused by e.g. opportunistic disease, pneumonia, TB, Kaposis sarcoma, cancer, dementia, extreme weight loss, meningitis, and toxoplasmosis.

Suggest why effective treatment of HIV in human populations will require the continual development of a mixture of many new drugs. (4) Because *HIV has many varieties of strains/antigens/protein coats, *some of these strains are/will become resistant to a specific/particular drug and so *would survive if only one/the same drug was used. *A mixture of drugs has more chance of getting rid of all/ more strains.*A concoction of drugs are used together because viruses have a rapid rate of mutation and a *rapid rate of multiplication.

Suggest why data about HIV infections are often estimates. (2)*Because HIV infection does not always produce symptoms (*especially in the latency period) or are *common of other diseases and so can be confused. In some cases a *test is needed to detect the symptomless HIV. *Only people who suspect they may have contracted HIV would have a test, *some people may not want to be tested/impossible to test everyone for statistics, especially as *new cases are arising/HIV patients are dying all the time or as *new strains of the virus are arising.TBState one characteristic symptom of TB other than coughingTubercules; bloody sputum; (general)body tissue wastage

Mycobacterium tuberculosis ..causes TB

Why is ingesting food containing TB unlikely to lead to its development? (2) Because the *bacteria is killed in the stomach/mouth/saliva/gastric juice *by HCL/lysozymes

Describe how the organisms that cause TB are taken up by macrophages. (3) First the *bacterium is recognised as non-self by the immune system, *they are labelled as such by B lymphocytes/cells. They are taken up into macrophages by *phagocytosis, the *process whereby phagocytes (macrophages or neutrophils) engulf the foreign matter and *enclose it within a vacuole where it is destroyed by enzymes contained in the lysosome.Bacteria and Viruses

Suggest two reasons why bacteria that cause infection are not visible in a photograph. (2) Because the *bacteria are too small and magnification/resolution is too limited; the bacteria may *not be stained or have been removed/destroyed e.g. by phagocytosis; *the bacteria are not present in the blood shown e.g. only a small region is shown and they may only be present at the site of the infection.

Photosynthesis:Suggest reasons why 95% of the light hitting the surface of a leaf is not used by the chloroplasts. (2)*Reflection; *incorrect wavelength/colour/ frequency; *light doesnt hit the chloroplast/ chlorophyll, it is transmitted; *light being in excess e.g. at max. photosynthesis so no more light can be used.

The light dependent reactions The products of the light-dependent reactions that are used in the light-independent reactions are reduced NADP and.... ATP Oxygen is produced when water molecules are split in the process of photolysis When light is absorbed by chlorophyll, it excites electrons

Describe the structures in a chloroplast that are involved in the LD reactions (3) The LD reactions involve the *thylakoids that 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 into photosystems/quantasomes; the membrane also has *ATPase/ ATPase channels.

Explain how the energy from light is made available in ATP molecules for the synthesis of organic materials. (6)*The light dependent reactions occur in the thylakoids *in the granum in *accessory pigments such as chlorophyll. The process begins when *light energy raises the energy level of two electrons so that they are excited, the electrons are then *released from the chlorophyll/ photosystem. They then travel down the *electron carrier chain, travelling to each carrier molecule through a series of *oxidation and reduction (redox) reactions, releasing energy/ *the electrons energy level falls. The energy released is used to *synthesise ATP from ADP and an organic phosphate ion *(phosphorylation); the *enzyme synthase/ synthetase is needed to make the ATP. *Photolysis of water produces 2 electrons which are used to replace those lost from the chlorophyll.

Explain how oxygen is produced during the light-dependent reactions of photosynthesis. (2) Using *energy from light the *photolysis *of water occurs that produces/releases oxygen

The light independent reactions/ The Calvin CycleRuBP combines with carbon dioxide in The light-independent reactions of the Calvin cycle. RUBISCO is the enzyme that catalyses carbon fixation. Carbon fixation takes place in.. the stroma of a chloroplast.

Explain why the light-independent stage cannot take place without the light-dependent stage. (3) Because the *products of the light-dependent stage are needed for/used in the light-independent stage/Calvin cycle. *Thee products of the light-dependent stage are reduced NADP and ATP, *rNADP is used in the reduction GP/carbon dioxide whilst *ATP is used as a source of energy.

Suggest why the development of plants depends on the rate of carbon fixation. (3) *Carbon fixation 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 is dependent on the rate of C-Fixation, if this increases so will the *GPP of the crop/plant.

Suggest how GALP may be used to synthesise cellulose. (5) *GALP is a 3C molecule that is used in the formation of *glucose a 6C sugar. *This synthesis involves enzymes; to make cellulose enzymes are also needed. *Cellulose consists of -glucose molecules that are joined by *1-4 *glycosidic bonds in *condensation reactions. *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.

The rate of carbon fixation is higher at 25C than at 14C for each of the six varieties of maize. Suggest an explanation for this. (2)*Temperature change affects the kinetic energy/movement of molecules/particles *therefore this effects number of collisions/enzyme-substrate complexes.Global Warming:Suggest one reason why some countries may decide to drain their marshy peat lands for the production of biofuels. (1) Producing Biofuels may increase the *countrys income as they can *export more fuel and *import less fossil/biofuels; the production of biofuels will also make *more jobs available to the general public. *Biofuels are also renewable whereas *fossil fuels are finite. *Using biofuels as an alternative to fossil fuels will help countries reach their carbon targets. Using peat lands will also make sure that there is *no loss of farmland, reducing ethical issues.

Suggest why the continued draining and clearance of peatlands may contribute towards global warming even though they may be used to produce biofuels. (5)*The combustion of biofuels releases carbon dioxide that has been recently removed from atmosphere therefore *there is no (net) increase in carbon dioxide in the atmosphere. This is a benefit as *carbon dioxide is a greenhouse gas *that absorbs infra-red radiation that has been reflected from the Earths surface, *it cannot escape into space, therefore the *carbon dioxide will cause the mean surface temperature of the Earth to increase. However, *clearing peat lands may release more carbon dioxide as carbon was once trapped in peats thousands of years ago; this *causes a net gain of carbon dioxide in the atmosphere. The process of clearing the peat lands will *involve machinery that releases carbon dioxide; the removal of any peat plants will also *reduce photosynthesis and thus the amount of carbon dioxide removed from the atmosphere

Suggest how scientists could use available data to predict future climate change.(3) Scientists could *extrapolate data *to use for modelling/investigation of correlations to help* provide evidence for global warming. *Using this data along with other sources will increase the predictions reliability.

Suggest why some scientists may not be convinced that data can be used to predict future climate change. (3)Because *there is not enough data to *confirm its reliability (*may be place specific). The fact that there are *great fluctuations in most climate change data suggest that there is no real trend (as scattered) and thus *poor representation of raw data. *A scatter of results may show poor reliability.In addition the method of* estimating temperature from growth rings of trees is questionable as *other environmental changes affecting the trees are not taken into account.

Scientists have estimated that.. will reduce CO2 production. Suggest why the may be supported by organisations that are concerned about global warming. (5) *The idea will result in less carbon dioxide (or methane), *which are both greenhouse gases/ cause the greenhouse effect *as they absorb/ trap heat/ infrared/ longer wavelengths (of radiation) *reflected from the Earth. *A reduction in these gases (CO2) will lead to a reduced greenhouse effect, *this means the Earths surface temperature is less likely to rise and that there is a *reduced possibility of climate change which can have effects such as the ice caps melting or crop failure.(If relevant) *methane has a greater greenhouse effect than carbon dioxide.

Suggest why some scientists do not agree that a reduction in the use of fossil fuels will prevent further global warming. (6)*It is clear that carbon dioxide is produced by using fossil fuels, however there is *no (direct) evidence that increased carbon dioxide concentrations leads to global warming. *Carbon dioxide is released from other processes such as respiration and the *removal of carbon sinks increases the concentration too, so reducing fossil fuels alone will not help. *Other greenhouse gases also have a contribution, such as CFCs, water vapour and methane that come from *other sources such as ruminant animals, paddy fields, melting ice, clearance of peat land. *Natural cycles/events/ phenomena may also be involved (in global warming) e.g. the suns solar cycle or volcanoes.*Evidence for this comes from the past and *this is not an indicator of future events/ limitations of climatic models. *Scientists may also be biased in their research depending on what country/ company employs them and their own self-interest/promotion. *We do not yet have an alternative source of energy that has no great problems associated with it (i.e. biofuels).

Explain how temperature has been maintained by the presence of carbon dioxide and methane in the upper atmosphere. (3)*Greenhouse gases such as carbon dioxide and/or methane *absorb/trap heat/infrared/long wave radiation *which is reflected/ (re)radiated from the Earths surface. *These gases prevent heat/infrared/long wave radiation from escaping. *Thus resulting in temperatures being maintained higher than they would otherwise be.

Suggest why temperatures below 0 C or above 40 C would be unsuitable for most organisms. (2) *At 0C metabolism/ named example stops/ is slow as *enzymes are inactive and cells are disrupted, this may be *because of water freezing or lower kinetic energy of molecules in cells. *Above 40C enzymes denature/ change their 3D shape, this means that *fewer enzyme-substrate complexes are possible/ the active site has changed/ theres a change in bonding.

Suggest how global warming may affect the distribution of species (3) *Global warming will increase the temperature (especially at the latitudes) *so that the temperature may become too high for any of the current species. *This new temperature may be above the maximum to be able to complete development/ above the lethal temperature limit. *Species may also move north/ to cooler regions or they may have a *change to their food source/predators/ competition.

Suggest why the lower and upper lethal temperatures limit the range of latitudes inhabited by (different species of frog). (2)*Temperature affects the survival/development/growth/metabolism/cell division of animals and *the development/growth/metabolism/cell division is affected by enzymes which are *affected by temperature. *And so as different frogs have different enzymes the will be able to survive in different latitudes. Explain why body temperature affects the rate of development of animals. (3)Because there is an *increase in the metabolic rate/enzyme activity as temperature rises due to *molecules having an increase in kinetic energy as the temperature rises; this means that there will be an *increase in the amount of enzyme-substrate complexes/collisions. *At lower temperatures there is inactivation of enzymes but at high temperatures there is denaturation of enzymes. *Thus temperature affects cell differentiation/growth/division.The carbon cycleDescribe the role of microorganisms in the recycling of carbon in the carbon cycle. (3) Microorganisms would *help in the decomposition/ putrefaction/ decay of dead organisms/ faeces *by eating the organic material through the process of external digestion and then *respiration. *Respiration releases carbon dioxide into the atmosphere *for photosynthesis. *They also will release methane in anaerobic conditions *which is then available as a fuel. *The microorganisms themselves will also, one day, be eaten or decompose.Ecosystems:The difference between abiotic and biotic factors is that..biotic factors involve organisms/living things whereas abiotic are physical/chemical/non-living factors.A species consists of.. individuals who can interbreed to produce fertile offspring.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).The metabolic process that best describes the process that accounts for most of the difference between GPP and NPP in plants is.. Respiration

Suggest two biotic factors that may influence NPP in grassland. (2) *Grazing by consumers/herbivores/named herbivore; *trampling; *shading by other plants/named plant; *competition from other plants; *disease.

Suggest how other animal populations of a habitat may be affected by changes in a lizard population. (2)Their prey may increase in number as *fewer are eaten by the lizard. *Other carnivores may increase *because there is less competition for food (from lizards), however the *lizards predator may decrease/eat other prey/migrate.

Suggest why an increase in temperature may cause an increase in NPP. (2) *The rate of (bio)chemical/metabolic/photosynthetic reactions increases due to an *increase in movement/kinetic energy of enzyme/substrate/molecules; *thus increasing the reaction rate because of more enzyme substrate interaction/ collisions.What is the unit J m2 year1? Joules/ energy per metre squared per year/ unit time.

Explain what is meant by the term niche, using the sea anemone as an example. (3) *The role/ purpose/ interaction of *an organism/ sea anemone/ species in a community; due to its *trophic level, i.e. if it is a *predator or *prey or provides a *shelter/ home for some animals.

Suggest and explain why the anemones contract when exposed at low tide. (3) Contracting *reduces surface area (to volume) ratio, so there is *less water loss and a smaller chance of dehydration/ drying out. This will also *reduce its visibility (to predators) *and so provides protection from predators/carnivores. As there is no *need for the tentacles to be exposed *energy will be conserved and not be wasted.

Suggest adaptations for bacteria living in a cows stomach. (3) The cows stomach has a *low pH/ (hydrochloric) acid which normally *destroys bacteria. The stomach may also have *low/no oxygen and *so they will have to use anaerobic respiration. They will also have to be *resistant to the stomachs enzymes, i.e. Protease, perhaps *by having a cell wall thats resistant to digestion. *They will also need to be adapted to the cows body temperature.SuccessionSuccession is.. The sequence of changes to a community/organism over a period of time.A climax community is..the final stage/sere/community of succession, it is self-sustaining/stable and has a dominant species or a few co-dominant species.Reproductively-isolated populations are..where *no (inter)breeding between (the population) can take place *because of a (geographical/ physical) barrier. Physical barriers include the populations having *different mating behaviour, *incompatible genitalia and *each population having a discrete gene pool, e.g. restricted gene flow, different mutation/alleles.

Describe what might happen if deflected succession stops (i.e. forest clearing). (3)*Taller (growing) plants could develop/ grow in the clear areas as they are no longer eaten, but there will be *the loss of low-growing plants/ clear zones. *Different animals/ species will appear as *secondary succession takes place where a *climax community of the taller plants is reached.

Suggest why/ how a community changes over time. (5)*Lichens and mosses enter 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 some water/minerals. *Then short-rooted plants enter, they out compete the pioneer plant, *these are able to grow in shallow soil and in turn *will change the soil structure to enable trees/ shrubs to grow, *these may 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 the amount of organic matter/humus.

Why is a climax community stable? (4)*A climax community is where (both) animals and plants are present/has many species/has high biodiversity; *there will be interaction between these species but they *will have reached a balanced equilibrium of species. *There may be a (co)dominant plant or animal species present.*This is stable as long as theres no change to the environment/human influence.Speciation and evolutionA gene mutation is.a change in DNA due to the change/deletion/addition/duplication/substitution bases/nucleotides.Genetic diversity in a species is..the variety of alleles in a gene pool A gene pool is The total of all the alleles in a population.Allele Frequency is. The proportion of one allele within a gene pool/population

Explain why there is likely to be a greater genetic diversity in a hybrid plant than in two separate species. (2)Because there are *different alleles in each of the two populations as *each population/ species is adapted to living in different environmental conditions. *This means that there will be different mutations in each population. *In a hybrid the alleles of the two different species will mix and hybrids will receive alleles from both species.

Suggest why scientists may classify organisms into sub-species rather than two separate species. (2)*If the organisms were allowed to interbreed and could *produce fertile and viable offspring they could be considered as sub-species. *The hybrids/offspring can flower and produce viable seeds.

Suggest how the two sub-species develop from a single ancestral population, use boar. (5) First a *few ancestral boar reach the island/ habitat from their original environment, there are now two populations that have *geographical separation perhaps by the sea or volcanic eruptions. *These populations are unable to interbreed (reproductive isolation) and so the *gene flow between the populations is restricted/ prevented. *There are only a small number of boar, on the island (founder effect), 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 are unique to the island (not found on mainland) ie food, habitat; the boar will *adapt to best suit these by natural selection, *those with the mutation are more likely to survive and reproduce. These mutations will *change the gene pool as they arise and possibly become more common, so the two are now different, *changing the allele frequency. *These changes will lead to phenotypic/ physiological/physical/ behavioural changes; as a result* allopatric speciation may occur (can no longer interbreed)

Explain how the two different species of flower on an island may have evolved from a single population of an ancestral species. (6)*The original population was increasing in size and spreading into a wider diversity of habitats where they were then *reproductively isolated, *i.e. diversity in flowering times, causing a *restriction of gene flow *between extremes of the population. Each habitat would have different environmental factors and so different selection pressures. *Mutations may then have arisen (*causing a change in the allele frequency) and *other plant features so that the *plants adapted to a specific region, advantageous features/mutations would allow the plants to *survive and reproduce, passing on new genes and creating *differences between gene pools.

Suggest how ecological isolation contributes to speciation. (2)*There may be different conditions /environments in each region, i.e. a temperature difference, so *there will be different selection pressures. The geographical isolation will mean that the two populations are *reproductively isolated from one another *causing a restricted gene flow/ separation of gene pools.

Suggest how genetic mutation may lead to speciation (2)*This will give a rise to different alleles/ gene pool, leading to *new/different phenotypes. This new *allele/gene may be advantageous, and so will be passed onto offspring; it could also be *disadvantageous.

Suggest why interbreeding does not take place between different populations of species. (3) These different species are reproductively isolated, meaning that they may have different *breeding times/ seasons, *courtship behaviour/rituals/displays/colour/songs. *Any offspring produced between the species may be infertile or not viable.

Suggest how a distinct species evolves from another species. (5) *Geographical isolation, e.g. a physical barrier between the population occurs/allopatric speciation, this means there is *reproductive isolation between the populations, *there is a restriction of gene flow between but not within the populations. *This creates two habitats that will contain different selection pressures *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 the conditions, *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.

Suggest how the allele frequency for a plant eating mutation could change as a forest develops. (4)*There will be a change in frequency of either allele e.g. mutant increases/normal decreases *due to the reproductive success of the mutant/non-photosynthetic individuals. *As the trees develop the pond will be more shaded this *(less light means) means less photosynthesis possible. *The photosynthetic individuals die/nonphotosynthetic individuals survive and *pass on the mutation/allele for using organic compounds, *thus allowing more organic nutrients in pond.AS related exam questionsPlantsPlant fibres that may be present in eaten material are: sclerenchyma fibres, xylem vessels and cellulose fibre.What plant tissue that would be the main source of the lignin in a plant? Sclerenchyma/xylem.What material would be synthesised to form the cell wall of seedlings? CelluloseWhat tissue would form the vessels in a root, following differentiation? Xylemhydrogen and glycosidic bonds are what would need to be broken to digest cellulose.

Describe the chemical nature of cellulose. (3) Cellulose is a *polysaccharide with an *unbranched/ straight chain. The cellulose is made up of *B glucose joined by *1-4 glycosidic bonds between the glucose molecules. Between each chain there are *intermolecular hydrogen bonds to hold the structure together.

Suggest two advantages of growing crops of wheat in glasshouses with artificial lighting rather than growing them in open fields. (2) Because *crops can be grown out of season/all year round; *plants photosynthesise 24 hours a day; *the crops will receive less physical damage from weather/animals *as pest control is easier. *You can also control other factors such as CO2, temperature, humidity and water supplyCell divisionWhat is the correct sequence of stages in mitosis? Prophase, Metaphase, Anaphase, TelophaseTranscription takes place in the nucleus

DNA and stuffTriplet of bases that could not be found in mRNA is.Adenine Thymine Guanine (etc)The sequence of triplets on a section of DNA used to form a strand of pre-mRNA is a. cistron

Explain why a molecule of DNA can be described as a double-stranded polynucleotide. (3) *It is double-stranded because it is made of two strands *joined together by hydrogen bonds between (the nucleotides) bases. *It is a polynucleotide as it is made of many nucleotides * linked together by phosphodiester bonds.Describe how the sequence of bases in a DNA molecule would be used to form the primary structure of a protein. (5)*A sequence of bases that form the genetic code determines the amino acid sequence, *one triplet of bases codes for an amino acid. *The DNA acts as a template when *transcription occurs (i.e. DNA unzips, mRNA synthesised); *the mRNA synthesised then moves from the nucleus to the cytoplasm, where *translation occurs (expand with ribosomes, codon-anticodon interaction). *tRNA will carry an amino acid and *peptide bonds form between the amino acids on different tRNA molecules; this is the *sequence/ order of amino acids is the primary structure of a protein.

How does mRNA form during transcription in the nucleus? (3) First the *DNA strands unzip, *one side of the DNA strand is the template strand that is used to from a mRNA strand *from free nucleotides. The nucleotides join by *complementary base pairing, *joined together by hydrogen bonds. *RNA- polymerase/ DNA Helicase are the enzymes involved in these reactions.

Describe how free nucleotides are bonded together in the correct sequence in pre-mRNA. (3) *The sequence of bases / nucleotides on DNA determines sequence on (pre-)mRNA as the nucleotides can only with their *complementary base pair e.g. AU / CG / GC / TA. *The bonds between the nucleotides form in condensation reactions and produce *phosphodiester bonds. *RNA-Polymerase is the enzyme that catalyses this reaction.

Explain the function of the codons at each end of a strand of mRNA, during the process of translation. (2)*The codons are either Start/ Stop codons; *start codons are needed to begin polypeptide synthesis and the Stop /Nonsense is needed to end polypeptide synthesis.

Suggest why the final triplet of nucleotides, on the strand of mRNA involved in the synthesis of this sequence of amino acids, did not correspond with any anticodon on tRNA. (2) As it is the *stop codon that is *used to end the sequencing/ further attachment of tRNA; *signalling the release of the polypeptide/ ribosome.

Suggest why a variety of different protein structures could be formed from the polypeptides synthesised using the mRNA molecules from a single gene. (3) Different protein structures could be formed as there are *variations of exons/ mRNA; this means that each mRNA strand will have a *different primary structure due to a different sequence of amino acids. *The secondary and tertiary structure of proteins will depend on the primary structure/ sequence *due to different bonds *such as Hydrogen/ Ionic/ Disulphide bonds. Each protein will be developed into *different 3D shapes as a result.

How does the translation of mRNA into the sequence of amino acids in a ribosome occur? (3) First *a specific amino acid becomes attached to tRNA *by the amino acid codon binding to the tRNAs anticodon *e.g. tRNA with alanine has CGA anticodon which binds to GCU on mRNA; only two tRNA molecules can be held on a ribosome at any one time. The tRNA and the amino acid bond by the formation of *peptide bonds using the enzyme *peptidyl transferase. *Only two tRNA and amino acids can be held in a ribosome at any one time.

Name and describe the structures where the polypeptide chain of an enzyme would be synthesised. (2)*On the ribosomes/poly(ribo)some *which is made of rRNA/ribosomal RNA. OR *on the rRNA which is *a ribosome attached to a membrane.

State two differences between fibrous proteins, such as actin and myosin, and globular proteins, such as enzymes. DescriptionDNA onlymRNA onlyBoth DNA and mRNA

Polymer formed from a single strand of nucleotides

Pentose present in thenucleotides

Adenine, cytosine, guanine and thymine present

Nucleotides linked byphosphodiester bonds

*Fibrous long/linear/straight chains and *Globular compact/spherical; *Globular are folded and fibrous are not; *Globular are soluble and fibrous are not; Fibrous are involved in structural functions (keratine) and globular are not; *Globular are involved in catalysis/metabolism (enzymes) and fibrous are not.

ConservationExplain how the work of zoos could be important to the survival of endangered species. (2) Zoos may run *captive-breeding programmes *which conserve alleles/genes/ the gene pool of a species and may run *reintroduction programmes/ re-introduce species into suitable habitats in the environment.

Suggest why it is important to conserve rare and endangered plants. (2 *This will conserve genetic diversity/genetic variation/biodiversity. It may also *prevent extinction. Conserving the plants may be good as they may be *useful as medicines/eq or they may be *depended on by animals for food or as a habitat, there may also be aesthetic reasons.

Suggest why many scientists consider that the use of protected reserves is likely to be more successful for the conservation of some animals than captive breeding programmes in zoos. (3) Reserves will cause*less stress/trauma/discomfort/depressed for the animals as *reserves provide a larger area for animals that require this. Animals are *more likely to breed in their natural environment and *larger numbers available will result in a wider gene pool. *There are problems associated with releasing animals back into the wild and these are avoided with reserves (I.e. habituation). *Disease is less likely to wipe out the whole population. *reserves allow natural interspecific relationships/communities to exist and *natural family/social structure/behaviour,* i.e. because their natural diet/food is available.MethodologyUsing a line of quadrats to investigate the distribution of organisms is a transectQuadrats may be divided up into smaller sections to... make it easier to estimate/measure /count the organisms & so the results are more preciseExplain the meaning of All other abiotic factors were controlled.(2) *Abiotic factors are non-living/non-biological/do not involve organisms.* If all other factors are controlled they are kept constant/the same.

Explain how a quadrat would be used to obtain the mean density of the two species in different areas. (3) *You will need to take several/more than 2 using *random quadrat positions, *these can be generated by a random number generator on your calculator (or other suitable method).*You would then count the number of individuals in each quadrat and then *calculate the mean density of the species using the total number of each species divided by the total area sampled (*you need to know the area of the quadrat to do this).

Suggest how results could be displayed in order to compare the effect of temperature on the growth of seedlings of two species. (3)You could use a *graph such as a *line graph with the *X&Y axes correctly drawn (i.e. temp at bottom/Y and growth rate/time at X). *You would use the same scale for the axes of both plants and would *plot each temperature/ species of plant separately.

Suggest why seeds may be germinated at 18 C before being placed in the experimental conditions. (2)*This was done to control variables. *18C may be the optimum/ suitable temperature for germination. * This technique makes sure that all the seeds are viable OR can germinate *and so increasing the validity of the investigation.

Suggest why taking photographs is a suitable method to count invertebrates. (2) *As they move about a lot *they are difficult to count *some might be counted more than once/missed out.

Why would it be difficult to determine which abiotic factor is influencing the behaviour and distribution of a species? (3)*Because for results to be (scientifically) valid *only one factor can be varied, *other factors need to be kept constant. *There will be many biotic factors in a habitat and these are difficult to control. *It will be difficult to set test factor values as a result.

Suggest how the scientists can have their results accepted by other scientists. (2) *Work needs to appear in a (Scientific) journal or being presented at a conference.*Peer review of work by other scientists to *consider the studys validity or reliability.

The temperatures used in this investigation were 0C, 10C, 20C, 30C, 40C and 50C.Suggest what the results of the investigation show about the minimum temperature required for photosynthesis in Elodea. Give a reason for your answer. (2)*The minimum temperature is between 0oC and 10oC /above 0oC but less than 10oC, *no photosynthesis occurs at 0oC as *water freezes at 0oC.*We know that the minimum temperature is somewhere between 0 oC and 10 oC but there are no measurements between these temperatures.

Enzymes control the rate of photosynthesis in Elodea. Discuss how far the results of this investigation support her conclusion. (4)Her conclusion is supported to some extent as *the shape of graph is typical of an enzyme-temperature graph, i.e. *the rate increases (up to 30 oC) *because more enzyme-substrate complexes/collisions between enzymes and substrates and *the rate decreases (after 30oC) due to enzyme denaturation. However it isnt supported as *other factors could be affecting photosynthesis (e.g. CO2 Concentration). *The gas/oxygen/carbon dioxide solubility also changes with temperature. *The graph shows evidence of correlation and not causation.

Describe and suggest explanations for the effects of these two abiotic factors on the distribution of (A. elegantissima) on this shore. (3) *There is no indication that temperature has an effect e.g. little variation, only 2oC so *distribution must be influenced by height above the low water mark *as the organism is more likely to dry out at higher levels. There would also be *a difference in food availability e.g. less at higher levels, more at lower levels as it is *more likely to be eaten at lower levels.

Suggest how this data could be analysed to assess the relationshipbetween these two abiotic factors and the distribution of (A. elegantissima on this shore). (2)You could *plot graph(s) of numbers of anemones against height and temperature/abiotic factors and then look for a *correlation.You could also *use a statistical analysis/test *such as the Spearmans Rank Correlation Coefficient.

1. group A = 720 and group B = 662/662.4 2. units correct = {dm3 day-1 / dm3 per day};

Suggest two reasons why a suspension of cells of a unicellular alga, in a solution, is more suitable for investigating CO2 production in photosynthesis than using leaves. (2)Because *samples of cells can be taken easily and there will be *no damage to plant/leaf /other cells during sampling; *The carbon dioxide level (in water) can be adjusted/maintained/changed easily; *As alga is single celled RuBP/GP/ products cannot pass into other cells/rest of plant, the alga will also on have *one kind of cell and thats the one that photosynthesises; You can *control the mass/number/surface area of cells to ensure that isnt another influencing factor; *genetically-similar cells will also be used which will reduce variation and so other factors.

Suggest why it would be advisable to illuminate the cells at a high light intensity during a photosynthesis and C02 experiment. (3) *As light is needed for the light-dependent reaction keeping it at a high intensity means *it will not be a limiting factor. *Thus C02 concentration is the only limiting factor. *ATP/ rNADP are produced during the light dependent reactions, *ATP/ rNADP/ light-dependent products are required for the light-independent reactions/ Calvin cycle/ carbon-fixation.

Both *RuBP and GP levels remain constant until the carbon dioxide is lowered; *these are used in the Calvin cycle. *At lower carbon dioxide levels the RuBP increases and drops and then stays constant, it *rises at 250seconds because it is being regenerated and it falls at 310seconds as being used to fixate carbon dioxide into GP. *The RuBP level remains constant once a (new) equilibrium is reached.*At lower carbon dioxide levels the GP drops and then stays constant, *it drops at 250 seconds because less carbon dioxide is available to convert into GP/less carbon fixation occurs. *It levels out at a lower level as carbon dioxide is still available but at lower level. *credit manipulation of figures (i.e. GP drops by 1au)

Compare the changes in mean environmental temperature between the pre-monsoon and the post-monsoon periods from 1600 to 2000. (3)*There is no/little change in pre-monsoon temperature but post-monsoon has risen overall, although they *both fluctuate the *fluctuations match each other; the fluctuations are within/less than 1oC. *The range of (mean) temperatures is greater OR shows greater fluctuations, in post-monsoon period. *Reference to a particular change in both e.g. both decreased between 1800 to 1850. *Credit correct manipulation of figures to compare with units.Calculate the overall percentage increase in the mean NPP from January to May. (3)*Correct readings from graph indicated e.g. (11 and 1) *Correct subtraction e.g. (11-1 / 10) *Correct division (by 1) x 100/1 to give 1000%

Using information from the graphs, describe and explain the relative effects of temperature and hours of sunlight on NPP in this grassland. (4)*Between January and April NPP increases as light increases, there is a *correlation between NPP and light; thus an *increase in light increases the rate of photosynthesis/ATP and so the energy available for Calvin Cycle, this is because *(credit correct details of photosynthesis) e.g. light results in excitation of electrons. *The changes in NPP occur after the changes in light/peak light is April and peak NPP is in May.But there is *no real correlation between temperature and NPP/reference to temperature fluctuating despite *temperature affecting how quickly enzymes work, for example *NPP falls from May but the temperature remains high. *Light and temperature are limiting factors.

Use the data in the tables to suggest which of the two species is better adapted for growth at a wide range of latitudes (distance from the equator). Give reasons for your choice.(4)*Sea plantain/Plantago maritima are better adapted. Because *different latitudes have different mean temperatures and the *sea plantain grows better in all threeTemperatures. Whereas *bog sedge/Kobresia simpliciuscula does not grow very well at lower temperatures/10oC and 14oC. *Credit appropriate comparative manipulated figures i.e. Sea Plantain has 73g more dry mass after 50days in 10oC.

Give reasons for your answers. (4) *As the rate of growth is linked to the rate of photosynthesis.*The top of the shore is shallower and where most wavelengths are available/lower shore is deeper where only green (and blue) wavelengths are available.*The red weeds reflect/do not absorb red light OR green weeds reflect/do not absorb green light, thus the *green seaweed has its highest rates in red/blue light and is at its lowest in green light but *would still grow well if all light waves were available. *The red seaweed is at its highest rate of photosynthesis in green light only and so *can only grow where only green light available.

*A. Because *in Central Europe temperatures never reach 25oC/data for 25oC is irrelevant/14oC is within the range/close to the average temperature and *the mean temperature is 15.25/15.3oC. *A has the highest rates of CO2 fixation at 14oC*therefore A will grow well in the temperature range of Central Europe.*All others would have relatively low yield at 14oC.

Suggest why the students were not able to draw valid conclusions about the effect of saturation of the soil by water on the distribution of the five plant species. (3)*Because saturation was not measured/depth of water does not give saturation data, there are *no data on other factors/variables that *may be affecting distribution/notcontrolled/confounding *i.e.Temperature. *Only one set of data is taken.

Mint

Common Duckweed

Soft Rush

Calculate the percentage of the mean GPP that remains as NPP within plants on Earth.The mean GPP for plants on Earth is 24.4 106 J m2 year1.The plants use 3.7 106 J m2 year1 of this energy in metabolic processes*24.43.7=20.7 *10024.4=4.09

Temperature

*The rate of growth increases as temperature increases between 13oC and 22oC/up to 22oC, it then *decreases between 22oC and 25oC/above 22oC *e.g. increases by 0.7a.u./4.5 times and decreases by 0.1a.u. This is because *enzymes are involved in growth; *molecules move about more/have more kinetic energy as the temperature increases *therefore enzyme and substrate molecules collide more/rate of enzyme-substrate complexes formation increases as temperature increases.But after a fixed point there will be *denaturation of some enzymes/protein molecules, *which decreases the rate of growth/reactions as fewer enzyme molecules are available.Suggest why it was important that this investigation was carried out at a high light intensity. (3)*So that each temperature has the same light intensity which *must be above the threshold/compensation point *below which no net photosynthesis takes place. This ensures that *light is not limiting factor/so temperature is the only limiting factor.*Photosynthesis produces material needed for growth.

Suggest two abiotic factors, other than light intensity, that would need to be controlled in this (temperature) investigation.*Wavelength/colour/frequency of light; *CO2 concentration; *pH of solution; mineral concentration