Life Sciences Grade 12 IEB Paper 2 2018 Memo

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE EXAMINATION NOVEMBER 2018 LIFE SCIENCES: PAPER II MARKING GUIDELINES Time: 2 hours 100 marks These marking guidelines are prepared for use by examiners and sub-examiners, all of whom are required to attend a standardisation meeting to ensure that the guidelines are consistently interpreted and applied in the marking of candidates' scripts. The IEB will not enter into any discussions or correspondence about any marking guidelines. It is acknowledged that there may be different views about some matters of emphasis or detail in the guidelines. It is also recognised that, without the benefit of attendance at a standardisation meeting, there may be different interpretations of the application of the marking guidelines. IEB Copyright © 2018 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER II – MARKING GUIDELINES Page 2 of 9 SECTION A QUESTION 1 1.1 1.1.1 A sequence of nucleotides/piece/section of DNA/order of nitrogenous bases on a chromosome coding for a trait/ polypeptide/protein. 1.1.2 Gregor Mendel did experiments to show how inheritance of characteristics/traits occurs, he discovered rules "factors" controlling characters for dominance and recessiveness of characteristics/traits, he was the first to show this. Discovered rules of segregation of genes and independent assortment of alleles for different characteristics by breeding experiments done on pea plants with contrasting characteristics worked out ratios of inheritance. 1.2 It occurs on the short arm of chromosome 22. 1.3 Met-Hb cannot be turned back into haemoglobin. Met-Hb accumulates, resulting in colour change of blood to blue/met-Hb is blue and therefore person looks blue. 1.4 1.4.1 F 1.4.2 F 1.4.3 T 1.5 1.5.1 Inheritance of a pair/two abnormal alleles results in the condition. The strain of the blue colour disappeared as the allele spread to families where it was unlikely to be paired with a similar allele. From pedigree – any example of children with condition and parents without condition (Luna Fugate) 1.5.2 Luna Fugate couldn't have it if it was sex linked as her father did not express it. Alva would have been affected as his mother would have passed affected X if sex linked It is on chromosome 22 which is an autosome / not on X or Y. It occurs on an autosome. IEB Copyright © 2018 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER II – MARKING GUIDELINES Page 3 of 9 1.6 Gametes: B b B b (or show this on the Punnett square/genetic cross). All genotypes correct; one to three genotypes correct (then phenotype is wrong). B b B BB Bb b Bb bb Phenotype: 25% chance of blue child. 75% chance of normal child (can also express as a ratio 1:3 blue : normal or fraction ¼ blue, ¾ normal). If pupil has incorrect gametes (B B and b b for example, or if sex linked), carry error forward and mark Punnett accordingly; no marks for phenotype. (cannot break up phenotype into "normal", "carrier" and "affected". If they do, only one mark given for correct percentage/ratio of sufferer – 25%) 1.7 Substitution one nucleotide/nitrogenous base has been replaced with another/C replaced by T. 1.8 30 000/3 = 10 000 (accept 9 999 if they have taken into account stop codon not coding for an amino acid or 9 998 if they have also taken into account demethylation of protein after translation (removal of methionine brought by start codon). 1.9 1.9.1 "Fugates married other Fugates" "Sometimes they married first cousins" "They married the people who lived closest to them even if they had the same last name" "All lived in isolation … It was natural that a boy married the girl next door." "Martin Fugate's descendants … all over the area." 1.9.2 Yes – it is important to acknowledge the existence of the people. It is in the public domain already. Most people in the story are dead anyway, not judgmental about inbreeding. No – there is a risk of discrimination. No evidence that consent has been given (consent needs to be given). Invasion of privacy. IEB Copyright © 2018 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER II – MARKING GUIDELINES Page 4 of 9 QUESTION 2 2.1 2.1.1 Producing copies of an organism/of individual cells that are genetically identical to the original. 2.1.2 Modified genome/DNA of organisms made by either inserting/ combining foreign DNA or DNA that has been edited/changed to contain foreign DNA. 2.2 Polymerase chain reaction (PCR) 2.3 2.3.1 B 2.3.2 A 2.3.3 A 2.4 Frog DNA/genes codes for characteristics that are different to dinosaurs as the sequence of nucleotides is different./Genes are different in different organisms/therefore codes for wrong (frog) proteins. 2.5 2.5.1 GUG CUG AAU 2.5.2 Val – Leu – Asn 2.6 1/57 × 100 = 1,75% or 1.8 2.7 Graph showing the number of bucardo from 1899–2000/ declining numbers of bucardo from 1899 – 2000 Number Time 2.8 2.8.1 Diploid 2.8.2 Haploid 2.8.3 Meiosis 2.8.4 Nucleus IEB Copyright © 2018 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER II – MARKING GUIDELINES Page 5 of 9 2.9 Ethical problems Ethical benefits Animals will be restricted to living in Bringing back animals may be zoos/laboratories. beneficial for the environment. Money should be spent on saving Our responsibility to bring back rare animals. species we caused to go extinct. CRISPR is potentially dangerous/ Development of new techniques unethical to edit DNA. could benefit animals/humans in future. They may be targets for hunters. Can be used to save species from becoming extinct May become extinct again – threats Restriction of animals to zoos/ are still present. laboratories for their protection Unethical to do this for the sake of seeing if it can be done. Problem with choosing which animals to bring back from extinction Health concerns for animals – dying soon after birth/breathing difficulties etc. IEB Copyright © 2018 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER II – MARKING GUIDELINES Page 6 of 9 SECTION B QUESTION 3 There is good evidence for a genetic cause for transgenderism NO – not genetic: no there is not good YES – Genetic: there is good evidence evidence – other influences have more/ other evidence SOURCE A SOURCE A Can be genetic changes/mutations Environmental (e.g. difference in brain influencing transgender. structure)/psychological/societal/hormonal X / Y chromosome differences influences. Brains determine gender (therefore genetic). Brains (our way of thinking) determine Cannot choose or change gender (therefore gender (therefore environmental issue). must have genetic basis. Takes 4 years to appear therefore must be Gender is a continuous characteristic – environmental. therefore genetic. Gender set by age 4 SOURCE B SOURCE B The higher percentage of identical twins who If genetic, then we would expect 100% of are both transgender supports a genetic identical twins to be transgender if one twin origin was transgender, therefore not a genetic 38% are transgender. cause. Only 38% of identical twins both being transgender (low) SOURCE C SOURCE C Common phase in adolescent life Common phase in adolescent life (Only SOME youth are "trying out" Youth are trying out transgender – most are transgender – not explain all cases) going through a phase or other emotional reasons By puberty or adulthood most identify as their biological sex (most have outgrown gender confusion) Most children outgrow transgender. More transgender present simply due to increase in acceptance. SOURCE D SOURCE D Gender is not the body we are born into Gender is not the body we are born into (gender indicates a genetic component) Parents, family and friends, media role models, culture, learning and conditioning. SOURCE E SOURCE E Studies based on very small sample size. Studies based on very small sample size. Testosterone release may be influenced by Differences in brain structure due to genetics hormones. White matter pattern in females due to environment (therefore transgender activity changes brain structure) Long-term exposure to stress diet or drugs can alter brain structure. IEB Copyright © 2018 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER II – MARKING GUIDELINES Page 7 of 9 SOURCE F SOURCE F Two decades of brain research (looking for Only 13 individuals have unique alleles of evidence of genetic origin therefore there RYR. must be something to it) Transgender often occurs in children very early on, therefore unlikely it's environmental. CYP17A1 and CYP19A1 genes possible contenders. Unique alleles of RYR3 gene has been found in some transgender individuals. Male transgenders more likely than non- transgender to have different receptor gene for testosterone, therefore reduces testosterone action, also works less efficiently at communicating testosterone message to cells. masculinise/feminise Another study found differences in the ER beta gene resulting in a lack of oestrogen receptors in female transgenders. SOURCE G SOURCE G Substances (e.g. medicines/pesticides) that inhibit testosterone function known to feminise fish. Oestrogen mimics can cause feminisation of fish, found in chemicals such as the pill. Substances can enter through contaminated water SOURCE H SOURCE H Foetal hormone insensitivity – AIH. Foetal hormone insensitivity – AIH. CAH – genetic causes for hormones cause Incorrect sex assigned at birth. females to have male sex organs. Hormonal medications taken during Intersex pregnancy can affect genitalia development. OWN: any extension of nature vs nurture. Own experiences can be brought in if appropriate. Genetic disorders – Klinefelters/Turners syndrome. Epigenetics Consuming hormone disrupters Total: 100 marks IEB Copyright © 2018 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER II – MARKING GUIDELINES Page 8 of 9 Note: Essay should be 2½ to 3 pages in length. Time allocation suggestion: Reading of sources 10 min.; Planning 10 min.; Writing essay 40 min. Possible mark 1 mark 2 marks 3 marks 4 marks (40) • Decision given • Decision given • Decision given • Key points present for • Key points developed for • Key points developed for Planning and against the and against the and against the argument argument argument 6 ×2 • Source references identified (e.g. Source A/own information) • Vague • Clear decision made Decision • Changed position within 2 essay • Up to ¼ of potential • Up to ½ of potential • Up to ¾ of potential • Source detail – very Use of knowledge detail in sources used to detail in sources used to detail in sources used to close to full potential from sources 8 support argument support argument support argument used to support ×2 argument • Some facts given • Many facts given beyond • Some facts given • Many facts given beyond beyond the source to the source to support beyond the source to the source to support Use of own support argument argument support argument argument 4 knowledge • Facts integrated into the • Facts integrated into the argument argument • Repetition mostly • Repetition mostly avoided avoided • Some minor digression • Some minor digression Content Relevance • Supporting argument • Supporting argument 2 relevant relevant • Quality of source extracts acknowledged IEB Copyright © 2018 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER II – MARKING GUIDELINES Page 9 of 9 Possible mark 1 mark 2 marks 3 marks 4 marks (40) • Writing consists of facts • Maximum if no clear • Supports the position • Strongly supports a clear with little linkage or decision in support • Reasoning is clear position reasoning • Reasoning correct, but • Minor errors in flow • Reasoning is very clear Quality of argument • Reasoning incorrect hard to follow • Linkage sometimes and succinct supporting • Ordinary: some linkage missed • Flow is logical 8 decision ×2 evident • Compelling with regular linkage • Well-integrated argument • One to two counter • Three to four counter • Integration of one to two • Integration of three to Fairness – counter opinions given from the opinions given from the counter opinions from four counter opinions opinions to 4 sources sources the sources into from the sources into decision argument argument • Writing is almost • Tone, language, • Tone is consistent and • Tone is mature and unintelligible terminology weak suited to scientific suited to scientific • Tone, language, • Introduction and language language terminology unscientific conclusion present • Good and appropriate • Excellent and and very weak language and appropriate language Presentation 4 • Introduction and/or terminology and terminology conclusion not present • Mostly appropriate • Correct paragraphing paragraphing with good transitions • Introduction and • Interesting introduction, conclusion have merit satisfying conclusion Scientific merit Essay shows academic rigour, accurate reasoning, insight and cohesiveness. 2 IEB Copyright © 2018