application to genetics

Question 1

explain what is meant by sequencing the human genome and describe the type of data that might be made available on line (3)

Answer 1

• order of nucleotides/bases in the DNA
• sanger sequencing
• descriptions of method used
• data/infromation would give loci/equences of individual genes
• coding for specific amino acids/ proteins
• descriptions of introns and exons

Question 2

explain how the extra information provided by the 100000 genomes prohect might be used in medicine (3)

Answer 2

• next generation sequencing/NGS
• locate genes responsible for rare genetic disorder/cancers /mutate sequences
• by comparing the genomes of sufferers with (normal genome/large number of indivudals)
• predisposition to disease/diagnosis/undertanding casues of diseaes
• developing treatements/gene therapy
• used in prenatal diagnosis

Question 3

describe how the scenario above with sharon that could get liver damage by taking a drug illustrates on possible benefical application and an ethical diallema of genome sequencing (3)

Answer 3

• sharon would find out if the drug would give her liver damge/ benefit is matching drugs to genetic make up of patient/personalised medication
• ethial dilemma is over rights of access to genomic infromation
• misuse of genetic information by employers/insurers
• wider implication on family health
• anxiety/distress caused by knowledge
• social discrimination

Question 4

what are sticky ends (1)

Answer 4

• the have unpaired bases
• they have exposed bases
• they are single stranded DNA sections

Question 5

Define the term plasmid (1)

Answer 5

ring of/circle of/loop of DNA (found in bacteria)

Question 6

why is it important to ue the same enzyme to cut open the plasmid and the piece of DNA (1)

Answer 6

so that the cut ends (of the fragment and the plasmid) are complementary

Question 7

Name the type of enzyme used to join the cut fragment into the plasmid (1)

Answer 7

• ligase

Question 8

explain why intron are more useful to genetic fingerprinting than exons (2)

Answer 8

• introns are non coding/blocks of repeated nucleotides/exons code for proteins
• so there is more variablitiy/more unique to the individual/number of times that the blocks are repeated varies/STRS vary

Question 9

give two features of DNa profiles lead to the identification of a suspect at a crime scene (1)

Answer 9

• same position and thickness of bands

Question 10

Dna at crime scene is often found in very small quantities PCR enables analysis of these small samples of DNA State how PCR makes this possible (1)

Answer 10

• nakes multiple copies/ampliies DNA

Question 11

the enzyme used in PCR has an important function during interphase in both mitois a and meiosis
name the enzymes used
and the enzymes function in interphase (2)

Answer 11

• DNA polymerse
• DNA replication

Question 12

why are two different primers needed for the strand of DNA (1)

Answer 12

• different nucleotide sequence at each end /one primer for each strand of DNA

Question 13

suggest why it is important to use primers which are specific to a vertain gene on each chromosome (1)

Answer 13

• enables/specific/the gene to be amplifies/to be copied / to be replicated

Question 14

Suggest why it is necesdday to express the quantity of genes as a ratio after using PCR and Dna electrophoresis (2)

Answer 14

• does not matter how many cycles in PCR/initial quantity/numbers of copies made
• ratio will be the same

Question 15

Explain how different types of enzymes are used to produce a gene package (4)

Answer 15

• restriction endonucleases/enzymes used to cut out the desired gene
• the same endonuclease/enzyme in used to oped the plasmids
• producing complementary/correspoinding sticky ends
• ligase is used to join/splice/attatch/adhere/anneal gene into plasmid

Question 16

explain the advantage of farmers having herbicide resistance plants (3)

Answer 16

• will not kill crop but will kill other plants/weeds
• reducing competition in the field
• allowing increased yield

Question 17

explain why environmentalists might have legitimate objectiosn to using GM crops resistant to herbicide resistance gene (2)

Answer 17

• increased use of herbicide
• reduction in biodiversity / lead to herbicide resistante weeks/superweeds / bioaccumulation in the food chain
• dispersal of pollen from crops engineered for herbicide resistance to wild relatives/weeds may lead to herbicide resistant weeds/superweeds
• dispersal of pollen from crops engineered for herbicide resitnace to other crops
• may contaminate organic crops
• GM crops produces a new protein
• unknown effects of eating a new protein

Question 18

explain the named enzymes would be used to cut genes from algae and splice them into cameline plants (3)

Answer 18

• restriction (endonuclease) enzyme used to cut out gene/DNA
• sticky ends
• same restriction enzyme used to open DNA in plasid
• ligase used to insert/anneal/splice gene into vector/plasmid

Question 19

explain why feeding genetically modified camelina seed which produce more omega 3 - fatty acids for farmed fish could benefit biodiversity (1)

Answer 19

• less wild fish will be harvested to feed farmed fish

Question 20

descrive three ways in which a DNa molecules differs from an RNA molecule (2)

Answer 20

• double stranded (not single/RNA is single stranded)
• deoxyribose not riboe
• thymine not uracil
• larger molecule

Question 21

State what is meant by a restriction endonuclease (2)

Answer 21

• it cuts DNA
• at a specific base sequence

Question 22

Suggest how the CRISPR technique could be used to modify mosquito eggs to produce sterile adult mosquitoes (3)

Answer 22

• make guide RNA with complementary sequence of target gene/fertility gene
• instert CRISPR/ cas 9 into eggs/cells
• and incubate/allow to grow/mature
• remove the gene that makes them fertile/affects meiosis

Question 23

explain how releasing these sterelised mosquitoes into the wild might beenfit humankind and suggest an ethical reason for not doing so (3)

Answer 23

• reference to reduced fertility in mosquitoes
• less mosquitoes = less malaria
• reference to right of humans to make another species extinct/effect on removal from food chain/exosystems/biodiversity/unknown effect of GM mosquitoes in the environment

Question 24

describe how a cDNA fragement containing bt gene can be prepared (3)

Answer 24

• extract mRNA from the bacterium (which is synthesising the proteins)
• use reverse transcriptase to synthesis single strand of DNA/cDNA using the mRNA as a template
• use DNA polymerase to produce double stranded DNA
• sticky ends are added to the end of each DNA strand of the DNA
• the DNa is copied many times using PCR

Question 25

decribe the processed by whcih genetically engineered plamids can be produced (3)

Answer 25

* plasmids from bacteria are isolated * restriction endonuclaeses/enzymes are used to open the plasmid at a specific point * producing sticky ends complementary to the DNA * DNa ligase is used to bing the DNA into the plasmid * antibioitic resistance genes/markers /lac Z are used to select bacteira containing the recombinant plasmids

Question 26

explain why there are concerns over the use of suhch a technqieu to increase resistance to insect pests in crop plants (3)

Answer 26

* dispersal of pollen from engineered crops to wild relatives/contamination of organic crops * unknown effect of eating new protein which is toxic to insects/ health concerns from eating GM crop * a reduction in biodiversity eg beneficial insects killed/affect on food chains * could result in resistance to protein in inects/selection pressure

Question 27

what is meant by the term gene therapy (1)

Answer 27

insert a (normal/correct)(gene/DNA seuqence)/ replacing defective/faulty genes with copies of a new DNA sequence /normal allele/normal gene

Question 28

1 target cells in affected tissues , 2 introduces gene into the egg, 3 inherited, 4 not inherited ort these under somatic cell therapy and germ line therapy (2)

Answer 28

* somatic cell therapy 1 and 4 * germ line therapy 2 and 3

Question 29

cystic fibrosis is caused by a mutation of the gene producing the protein CFTR explain how the prescence of this altered protien results in the production of thick, sticky mucus and how this accounts for respiratory sysmptoms of the diseases (4)

Answer 29

 CFTR is a {Channel protein / carrier protein / ion pump}; Not active transport alone  Blocks {transport / movement} of chloride ions out of cells (into mucus) / ORA;  Water retained in cell / water prevented from leaving / no osmosis;  Unable to remove mucus in lungs;  {Infection/ more susceptible to disease} / coughing {more likely / increased};  {Narrowing / blocking} of air passages (so reduced air flow);  {Increased diffusion distance / reduced surface area} for gas exchange / insufficient oxygen received / not enough oxygen absorbed;

Question 30

describe one technique that could be used to introduce functional CFTR genes into someone with cystic fibrosis (3)

Answer 30

 (Modified / normal / correct) genes are inserted;  into liposomes / virus (as vector);  Liposomes fuse with cell membrane / virus infects cell / ref to endocytosis;  (Modified) gene passes through membranes / into cell;  Applied by aerosol / spray / inhaler;

Question 31

explain why the replication of DNA is described as semi conservative (1)

Answer 31

Each new DNA molecule consists of one {original / parent / old / template} strand and one new strand of DNA;

Question 32

Explain in PCR why DNA is first heated to 95 degrees (1)

Answer 32

To (break bonds between DNA strands or bases to) separate original DNA into two single strands;

Question 33

explain in PCR why the temperature then reduced to 55 degrees (1)

Answer 33

Triggers / Allows {primers / short pieces of RNA / single-strand DNA / free nucleotides} to {bind / attach / join} (to single stranded DNA);

Question 34

explain in PCr why the temperature is then increased to 70 degrees (1)

Answer 34

TAQ / DNA polymerase {makes nucleotides join / makes a strand of DNA / catalyses the synthesis of a complementary strand};

Question 35

name the enzym involved in teh transcirption stage of protein synthesis (1)

Answer 35

RNA polymerase

Question 36

tetracycline binds to bacterial ribosomes explain how tetracycline stops protein synthesis in bacteria (3)

Answer 36

 Translation prevented;  Tetracycline {binds to / blocks / inhibits} {mRNA triplet / codon / CGC / second attachment site};  {Anticodon / tRNA triplet} cannot pair with {mRNA triplet / codon} / cannot form codon-anticodon complex;  Amino acid not added to polypeptide chain / peptide bonds not formed;

Question 37

explain the results of the replica plate containign ampicillin (2)

Answer 37

 Colonies {1, 2, 3 & 6 / shown / present} have taken up {plasmid / ampicillin resistant gene}; Reject taken up human gene; Ignore recombinant plasmid;  Because they are resistant to ampicillin / able to grow on ampicillin;  4 and 5 have not taken up the {plasmid / ampicillin resistant gene};  And so are not resistant to ampicillin;

Question 38

Explain the results of the replica plate containing tetracycline. (3)

Answer 38

 Colonies 1 and 3 do not have the gene / recombinant plasmid;  As they (remain) resistant to tetracycline / gene for tetracycline resistance has not been {disrupted / destroyed};  Colonies 2 and 6 do have the gene / recombinant plasmid;  Tetracycline resistance destroyed / prevents gene from being expressed;

Question 39

give an account of the principles involved in cloning mammals, including the use of stem cells (8) discuss the possible objections to the use of stems cells (2)

Answer 39

A (Embryo cloning) {in vitro fertilised egg / zygote} divides to form {a ball of cells / embryo} / undergoes mitosis; 1 B Embryo is split into separate cells; 1 C Before differentiation / 8 cell stage; 1 D (Nuclear transplant) nucleus / DNA may be removed from diploid / somatic / udder; 1 E (Nuclear transplant) nucleus / DNA may be removed from egg / ovum / secondary oocyte; 1 F Introduce nucleus to donor egg / Donor and recipient cells are fused together; 1 G The embryo is allowed to develop in a surrogate; 1 H Animal born is genetically identical to the original donor; 1 I Reference to totipotent / cells are able to differentiate into more than one cell type / form a whole organism; 1 J Example of tissue that contains stem cells – bone marrow, testes, embryonic stem cells; 1 K Human stem cells could be used to {grow into required organ or tissue / therapeutic uses (treat range of diseases) / or named example; 1 L Less likelihood of rejection / no need for immunosuppressant drugs 1 (Any 8 from 13) M Embryos have to be destroyed to provide the stem cells/ Pro- life issues -embryos have the potential for independent life (in the future); 1 N Unknown long term side effects of stem cells; O Genetic modification of humans for non-medical reasons / eugenics issues related to selection of embryos;

Question 39

suggest and describe a method which could have been used to clone these dogs (4)

Answer 39

Egg taken; Nucleus/DNA removed; Nucleus/DNA (from adult dog Trakr) taken from a body cell (skin) placed into enucleate egg/2 cells fused. Stimulated to divide; Placed/implanted into uterus of surrogate/bitch (allow:dog); (Who is at) correct stage of reproductive cycle. Somatic cell nuclear transplant/transfer (not: embryo cloning)

Question 39

the coat colour of the puppies is not the same suggest two reasons to explain the difference (2)

Answer 39

(Somatic) mutation; Environmental influence or description; Different ages. (not: cloned at different times)

Question 39

The phenotype of dogs such as Trackr have been produced by artificial selection. Suggest how natural selection has brought about evolution of coat colour in other species. (4)

Answer 39

a. More offspring produced than can survive, overproduction; b. Numbers in a species remain constant; c. Large number die; d. Struggle for survival/competition; e. Variation or description of coat colour; f. Selection pressures favour one phenotype g. Those with beneficial alleles better chance of survival/selective advantage; h. Reproduce/breed; i. Pass on beneficial alleles to offspring.

Question 39

State how each of the following are used in the formation of recombinant DNA. (1) Restriction endonuclease

Answer 39

* cuts the DNA into smaller segments/at specific base sequences

Question 40

State how each of the following are used in the formation of recombinant DNA. DNA ligase (1)

Answer 40

joins the sections of DNA together/splices gene

Question 41

State how each of the following are used in the formation of recombinant DNA. reverse transcriptase (1)

Answer 41

enzyme which uses RNA as a template for making a DNA molecule

Question 42

State how each of the following are used in the formation of recombinant DNA.marker gene (1)

Answer 42

a gene which enables the detection of a bacterium which has taken up a genetically modified plasmic/with the gene

Question 43

State how each of the following are used in the formation of recombinant DNA. PCR (polymerase chain reaction ) (1)

Answer 43

replication of DNA molecule to give multiple copies (amplify DNA)

Question 44

what was the aim of the human genome project (2)

Answer 44

* Determine sequence of bases throughout all human DNA; * Identify genes formed by bases; * Find location of genes; * Produce database of genes.

Question 45

give two potential uses of information gained from the human genome project (2)

Answer 45

* Identification of carriers/allow genetic counselling; * Checking embryo before implantation; * Pre/post natal testing; * Checking to see if there is a risk of a condition developing; * Extra screening/regular health checks/life style advice; * Drug targeting; * Possibly gene therapy/forensic/identity.

Question 46

state one way in which information gained from it could be misused from the huan genome project (1)

Answer 46

* Cause anxiety; * Should a line be drawn between medical treatment and enhancement; * Ref problems if information gets into wrong hands, insurance, employment/discrimination, etc. (not: designer babies)

Question 47

Genetic engineering involves the introduction of DNA from one species into another. Describe the process by which bacteria have been produced which synthesise human insulin. (10)

Answer 47

A. Cells from Islets of Langerhans; B. gene for insulin located; C. gene/DNA probe; D. (cut gene) restriction endonuclease /enzyme; E. mRNA for insulin; F. reverse transcriptase qual.; (e.g. make DNA from RNA) G. DNA polymerase qual.;(e.g. make DNA double stranded) H. sticky ends on gene; I. bacterium/E.coli (is source of); J. plasmids; K. same restriction endonuclease; L. sticky ends with complementary bases; M. DNA ligase; N. ref marker/tracer genes/antibiotic resistance; O. recombinant DNA. P. introduced back into bacterium/ E. coli;

Question 48

distinguish between DNA ligase and DNA polymerase (2)

Answer 48

Ligase - {splices / joins} two {sections of DNA/ groups of nucleotides/ sugar phosphates} together; Accept joins (donor) DNA into a {plasmid/ vector} Reject joins strands of DNA Polymerase - joins single nucleotides to end of a DNA chain; Accept addition of {free/single} nucleotides to {exposed (DNA) bases/ template};

Question 49

distinguish between a gene and an allele (2)

Answer 49

Gene - {section of DNA / chromosome} which codes for a {single polypeptide / protein/ sequence of amino acids}; Allele - {different/ specific} {forms/ versions} of {a/same} gene; Accept different types of the same gene

Question 50

Describe the principles and techniques involved in the cloning of plants. Give the advantages and disadvantages of this process. (10)

Answer 50

A. Asexually produced and genetically identical; B. Artificial, cuttings ; C. micropropagation; D. meristem removed; E. meristem is {able to differentiate/ give rise to different cell types/ totipotent} F. cut into small pieces/ explants; G. Culture under sterile conditions; H. On a nutrient {medium/ agar jelly}; I. (Cells divide to form a) Callus ; J. Callus divided and {allowed to differentiate into a plantlet/ treated with plant growth substances to promote root and/or shoot growth}; Max 8 Advantages, K. speed of production; L. Production of large numbers; M. {Identical/ desired} line/ crop uniform/ disease free; Disadvantages N. Must maintain sterile conditons to avoid introduction of pathogens; O. Genetic instability/ increased mutation rate; P. loss of genetic variation/ reduction gene pool/ all susceptible to same diseases;

Question 51

The Ebola virus capsule glycoprotein has been purified and injected into mice which then produce antibodies against the protein. The genes for these antibodies have been cut from mouse DNA and inserted into Tobacco Mosaic Virus (TMV) genes. By allowing these viruses to infect tobacco plants, genetically modified tobacco plants can be grown which produce antibodies against Ebola. (i) Name the enzyme that would be used to cut the antibody producing gene from the mouse DNA.

Answer 51

restrictio (endonuclease enzyme )

Question 52

The Ebola virus capsule glycoprotein has been purified and injected into mice which then produce antibodies against the protein. The genes for these antibodies have been cut from mouse DNA and inserted into Tobacco Mosaic Virus (TMV) genes. By allowing these viruses to infect tobacco plants, genetically modified tobacco plants can be grown which produce antibodies against Ebola name the vector used to transfer the mouse gene (1)

Answer 52

tobacco mosaic virus /TMV

Question 53

The Ebola virus capsule glycoprotein has been purified and injected into mice which then produce antibodies against the protein. The genes for these antibodies have been cut from mouse DNA and inserted into Tobacco Mosaic Virus (TMV) genes. By allowing these viruses to infect tobacco plants, genetically modified tobacco plants can be grown which produce antibodies against Ebola name the enzyme that would be used to insert the mouse gene into a vector (1)

Answer 53

DNA ligase

Question 54

The Ebola virus capsule glycoprotein has been purified and injected into mice which then produce antibodies against the protein. The genes for these antibodies have been cut from mouse DNA and inserted into Tobacco Mosaic Virus (TMV) genes. By allowing these viruses to infect tobacco plants, genetically modified tobacco plants can be grown which produce antibodies against Ebola bacteria could be used instead of tobacco plants to produce the antibodies what vector would be used in this case (1)

Answer 54

plasmids

Question 55

The Ebola virus capsule glycoprotein has been purified and injected into mice which then produce antibodies against the protein. The genes for these antibodies have been cut from mouse DNA and inserted into Tobacco Mosaic Virus (TMV) genes. By allowing these viruses to infect tobacco plants, genetically modified tobacco plants can be grown which produce antibodies against Ebola give one advantage of using bacteria instead of tobacco plants (1)

Answer 55

* bacteria/product produced more quickly/cheaply / light not needed /less space needed/ reproduce asexually so alway clone the gene

Question 56

The technology described in part (d) was used during the Ebola outbreak of 2014 to develop a drug called ZMapp. The drug was only used to treat two Americans who had been working as medics in Africa. Its use was controversial because the drug had not been tested on humans. At the time there were only a few doses of ZMapp available. (i) Suggest a reason why the decision to use the drug was taken, even though it had not been tested. (1)

Answer 56

they would have died anyway

Question 57

The technology described in part (d) was used during the Ebola outbreak of 2014 to develop a drug called ZMapp. The drug was only used to treat two Americans who had been working as medics in Africa. Its use was controversial because the drug had not been tested on humans. At the time there were only a few doses of ZMapp available. Apart from the fact that drug had not been fully tested, give one reason why using the drug in the way described could be considered unethical. (1)

Answer 57

* the americans had no more right to treatment than the africans * accept mouse welfare/rights