5 (a) Pigs are farm animals used for livestock in some parts of the world. The first genetically modified (transgenic) pigs were produced in 1985. Foreign DNA was injected directly into the nuclei of zygotes. The foreign DNA was made up of two components: • the gene coding for human growth hormone • a section of mouse DNA that, in the presence of metal ions, allows transcription to begin.

Mark scheme

Marking points from the official mark scheme (May/June 2018). The mark or mark type is shown in brackets.

1. [2] any two from: (transgenic pigs – ora for normal pigs) 1 GH (concentration) higher / GH always present not just at certain times ; 2 hGH, works for longer / broken down less quickly (than pig GH); 3 increase in cell signalling; 4 increased / activates, (growth) gene, expression / transcription ; 5 increased / stimulates, cell division / mitosis; 6 (make) more, muscle / bone / fat;
2. [3] any three from: 1 (mouse DNA/ it) is, the promoter ; 2 (where) RNA polymerase / transcription factor(s), bind ; 3 controls / allows / ensures / is needed for, gene expression / gene activation / mRNA production / hGH production; 4 gene can be, switched on / transcribed, by adding metal ions; 5 idea of controlling, when / where / how much, the gene is, expressed / transcribed ;
3. [3] NO arguments (any two to question max three): 1 few offspring / don't pass on gene(s) / unsustainable / assisted reproduction is expensive (as problem with mating) ; 2 cost of healthcare / less growth / die young (due to ulcers); 3 people may, avoid / refuse to buy / pay less for, GM food ; 4 (GM) production cost, expensive / outweighs benefits (as 1% success); YES arguments (any two to question max three): 1 greater yield / more meat (as higher, body mass / muscle); 2 higher price / worth more money, as more muscle to fat ; 3 sell / slaughter / process, earlier / at younger age;
4. [2] any two from: unethical/not good/not right, because: 1 pigs, suffer / have (stomach) ulcers / experience pain; 2 pigs cannot, behave normally / move much / exercise / keep fit / socialise / mate ; ethical/good/right, because: 1 more / better quality, meat / food, for humans ; 2 pigs suffer less than (normal) pigs given hGH by injection ;
5. [2] any two from: success rate (in altering gene) is, greater / 100% (instead of 1%); (only) specific gene is altered / targets gene more precisely; (unwanted) gene is, removed / deleted / disabled / knocked out;
6. [3] one or two arguments about statement's truth to question max 3: 1 not selective breeding as, DNA / genes, manipulated / altered / changed / removed ; 2 not selective breeding as IVF is used ; 3 not selective breeding as no, crossing and, selection (of offspring) / repetition ; 4 not genetic engineering as no new gene is put into, organism / zygote ; one or two reasons why more acceptable to question max 3: 5 no foreign gene inserted / no cross-species gene transfer ; 6 (only) one / single, gene, altered / silenced ; 7 (application) reduces, suffering of/ (viral) disease in, pigs ;