Edexcel A Level Biology Paper 1 Mark Scheme June 2022 | Advanced Biochemistry | Microbiology and Genetics

Edexcel A Level Biology Paper 1 Mark Scheme June 2022 | Advanced Biochemistry | Microbiology and Genetics.A description that makes reference to three of the following: • (contact between sperm and secondary oocyte results in) acrosome reaction (1) • meiosis is completed (1) • cortical reaction takes place (1) • fusion of sperm {nucleus / genetic material} with {nucleus genetic material} of ovum (1) ACCEPT ovum / egg cell / female gamete description e.g. enzymes are released from the acrosome DO NOT ACCEPT if described after cortical reaction or fusion of two cells ACCEPT description e.g. cortical granules are released that {hardens the membrane / forms a fertilisation membrane} ACCEPT egg cell / nuclei of the gametes (3) Question Number Answer Additional Guidance Mark 3(a) The only correct answer is A B is incorrect because Plasmodium is the genus name not the species name C is incorrect because Plasmodium causes malaria not Puccinia D is incorrect because Plasmodium causes malaria not Puccinia (1) Question Number Answer Additional Guidance Mark 3(b) A description that makes reference to three of the following: • {gene / DNA / genetic material} coding for toxin isolated (from the spiders) (1) • using {restriction enzymes / (restriction) endonucleases} (1) • (spider) gene inserted into fungus using a {vector / named vector} (1) • genetically-modified fungi {identified / cloned / cultured} (1) ACCEPT mRNA isolated and used to synthesise the gene / base sequence of gene determined and used to synthesise a gene ACCEPT in context of vector DNA e.g. virus / plasmid / gene gun / injection ACCEPT replicate / reproduce (3) Question Number Answer Additional Guidance Mark 3(c) An explanation that makes reference to three of the following: • not unethical as mosquitoes not killed (1) • risk of other organisms being affected by the genetically-modified fungus is avoided (1) • organisms that feed on mosquitoes will not lose their food supply (1) • some people believe that modifying DNA is {wrong / unethical} (1) ACCEPT converse for other approach e.g. toxins could harm other organisms, transfer of genes into other organisms ACCEPT unknown risks ACCEPT biodiversity maintained / ecosystems not disrupted / food chain not disrupted