A-LevelBiologyGenetic technology9700/42 · May/June 2021 · Q49 Marks

(a) Genetic technology involving the creation of recombinant DNA can be used to treat different human diseases. These include diseases such as diabetes that may have multiple causes and inherited disorders that are caused by a single gene. (b) A new application of recombinant DNA technology uses the genetic modification of a plant to prevent disease. It aims to prevent the most common source of food-borne disease, which is caused by eating food contaminated with pathogenic Escherichia coli bacteria. Scientists genetically modified edible spinach plants to produce colicins. Colicins are antimicrobial proteins that can kill pathogenic E.coli. Colicins are normally made by other bacteria. An experiment was carried out to test this application by spraying an extract of genetically modified (GM) spinach in buffer solution onto raw meat contaminated with pathogenic E.coli. The meat was stored at 10°C for varying lengths of time before the numbers of viable (living) pathogenic E.coli bacteria were counted. Fig. 4.1 shows the results. [Figure 4.1]

(a)Outline two different ways of using recombinant DNA technology to treat these diseases. diabetes single gene disorder[2]
(b)(i)With reference to Fig. 4.1, evaluate the effectiveness of using GM spinach spray on raw meat to prevent food-borne disease.[4]
(b)(ii)Regulatory authorities may not approve the use of GM spinach spray on raw meat to protect consumers. Discuss the concerns that may stop regulatory authorities approving this application of recombinant DNA technology.[3]

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Mark scheme

Marking points from the official mark scheme (May/June 2021). The mark or mark type is shown in brackets.

[2] diabetes: insulin from (GM) bacteria; A ref to, yeast / animal cells single gene disorder: gene therapy or insert, functional / normal / dominant, allele into, target / somatic / stem, cells or genome; A gene R replacing one allele with another
[4] any four from: valid 1 GM spinach decreases number of, bacteria / E.coli or GM spinach has lowest number of, bacteria / E.coli ; 2 at all times (meat is stored) or the longer the time stored the more effective it is or most effective after 72 hours ; 3 data quote comparing no treatment or buffer alone with GM spinach extract at stated time ; not valid 4 no treatment / buffer alone, (also) decrease number of, bacteria / E.coli or GM spinach does not kill all, bacteria / E.coli ; 5 meat should not normally be left at 10°C or people unlikely to eat meat left at, 10°C / for 72 hours ; 6 does not test effect on people / AW ;
[3] any three from: 1 may alter, taste / texture / quality, of meat; 2 may be unsafe for humans / allergies / side effects ; 3 may harm, gut / beneficial, bacteria or may increase growth of, non-colicin sensitive / other, bacteria ; 4 contaminate food labelled as organic / AW ; 5 E.coli / bacteria, may develop resistance to, (spray / colicins); R GM spray / colicins, cause mutation 6 AVP; e.g. may decrease food hygiene practices in, meat factories / abattoirs / restaurants / food outlets ;

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