Life Sciences Grade 12 IEB Paper 1 2016 Memo

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE EXAMINATION NOVEMBER 2016 LIFE SCIENCES: PAPER I MARKING GUIDELINES Time: 3 hours 200 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 © 2016 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER I – MARKING GUIDELINES Page 2 of 10 QUESTION 1 1.1 COLUMN A COLUMN B [C] Genetic material formed by combining genes A Gonosomes from two or more sources. B Clones [G] Enzyme that breaks or cuts sections of DNA. C Recombinant DNA [I] When both forms of a gene in a cell are identical. [H] The physical outward expression of a pair of D Surrogate alleles. E Genotype [A] Chromosomes containing information relating to the sex of the individual. F Plasmid [L] Different forms of the same gene. G Restriction enzyme [J] A condition in which more than two sets of H Phenotype genes are present in a cell. I Homozygous [B] Genetically identical individuals. J Polyploidy [D] A mother who carries and gives birth to an individual that is not her own. K Ligase enzyme [F] A circular strand of DNA found in bacteria often L Alleles used to transfer genes to other organisms. 1.2 1.2.1 1.2.2 1.2.3 1.2.4 1.2.5 1.2.6 D (1) B (2) A (1) A (1) C (1) D (2) 1.3 STATEMENT A, B OR C 1.3.1 Infertility can be due to problems in both women and C men. 1.3.2 The majority of fertility problems in women are due to B endometriosis. 1.3.3 The single largest contributing factor to female infertility A relates to ovulation. 1.3.4 Stress contributes to female infertility. C 1.3.5 There may be factors affecting female fertility that are not A mentioned in the pie chart above. IEB Copyright © 2016 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER I – MARKING GUIDELINES Page 3 of 10 1.4 1.4.1 A: TSH B: Thyroxine 1.4.2 Increases/stimulates metabolic rate/rate of cellular respiration. 1.4.3 (a) Negative feedback mechanism/homeostasis. (b) Increased levels of thyroxine inhibit production of TSH so that no more thyroxine will be produced. 1.4.4 Growth Hormone/Somatotrophin, LH, FSH, Prolactin, MSH, ACTH, Oxytocin, ADH, ICSH (only mark first two) 1.5 1.5.1 Diploid 1.5.2 STRUCTURES NUMBER PRESENT Chromosomes 4 Homologous pairs 2 Bivalents 0 1.5.3 Diagram of a cell on Metaphase II Two chromosomes Double threaded One long and one short Lined up on equator Single file 1.6 1.6.1 ITEM ANSWER 1. Oviparous D 2. Viviparous 1. Sexual reproduction A 2. Asexual reproduction 1. External fertilisation B 2. Internal fertilisation 1. Courtship behaviour absent B 2. Courtship behaviour present 1. Evidence of parental care A 2. No parental care evident 1.6.2 Reproductive strategies are (structural, functional and behavioural) adaptations/mechanisms that improve the chances of successful fertilisation/survival of offspring. IEB Copyright © 2016 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER I – MARKING GUIDELINES Page 4 of 10 1.6.3 Parental care: by carrying the babies on her back she protects them from predation ensuring that greater numbers survive. Courtship/mating dance: ensures species specific mating and ensures that the fittest individuals are selected, which benefits the species. Internal fertilisation/female takes sperm into her body: increases the chances of fertilisation by protecting gametes and embryos from dangers of predation/dehydration. Ovoviviparity/the eggs are held inside the female body until they hatch inside the body. This protects eggs from predation/dehydration./Eggs are nourished by own yolk. 520 1.7 1.7.1 ×100 = 65% 800 1.7.2 Cultivar 1/2/3/4/5 has the greatest reproductive success./Cultivar which have most flowers will produce more apples. (concise statement) 1.7.3 (a) Independent: Variety/Cultivar (b) Dependent: reproductive success/number of flowers that develop into fruit/number of fruit that develop. 1.7.4 These results are not valid as the following controlled variables were not standardised: • Age of trees was not standardised • Conditions were different • Location was not identical • Exposure to pollinators was not standardised OR These results are valid: • The trees all belonged to the same species • All trees were grown in Western Cape • The same number of trees was selected • Random sampling 1.7.5 Use third column because all that matters is how much fruit you collect/because reproductive success can be determined by how much fruit you collect. OR Use column 4 because plants with higher reproductive success are better adapted to local conditions. OR Difficult to determine because we do not know which apples sell best or how much it costs to grow each cultivar. IEB Copyright © 2016 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER I – MARKING GUIDELINES Page 5 of 10 Which part of the Labelled 1.7.6 Name Function flower did it part originate from? Protection/nourishment of A Seed Ovule embryo/continuation of species. Flesh/fruit/swollen Aid in dispersal of B Ovary/receptacle ovary wall seed. QUESTION 2 2.1 2.1.1 Protein synthesis 2.1.2 (a) C (b) B (c) A 2.1.3 C E D A B or C E A B D or CEADB (2 or 0) 2.1.4 UCG/GAU/UAC 2.2 2.2.1 (a) 12 (b) 12 (c) 4 (d) 2 (e) 4 (f) 2 2.2.2 (a) To map out/sequence/identify location of all the genes in the human genome/to work out the base pair of all genes in the human genome. (b) Enabled the development of gene therapy/treatment in the treatment of genetic conditions. Allowed for the identification of faulty genes in a human genome and thus assists in diagnosing causes of certain diseases/conditions. Assists doctors in selecting correct medicines to treat certain patients. Study how genes influence human development. Develop new drugs to treat genetic diseases. Provide insight into human origins and evolution. 2.3 2.3.1 Type 1 = Insertion Type 2 = Deletion Type 3 = Substitution IEB Copyright © 2016 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER I – MARKING GUIDELINES Page 6 of 10 2.3.2 The wrong amino acid would be inserted so incorrect protein would be made. 2.3.3 • Beneficial mutation. • The individuals who carried this mutation would be selected for as they were better adapted to the changing condition/have an advantage. • They would thus survive and pass on their genes to the next generation causing species to evolve/change over time to form a new species. • Those who did not have favourable mutation would die under unfavourable conditions. (max 4) OR • Harmful mutation. • The individuals who carried this mutation would die out as they were less adapted to the changing condition/were at a disadvantage. • They would thus not pass on their genes to the next generation. • Those who did not have unfavourable mutation would survive. • Direction/pathway of speciation changes/altered as gene pool would change (although this event alone is not enough to cause speciation). (max 4) 2.3.4 (a) Parent Genotypes: Nn x Nn N n gametes N NN Nn combinations n Nn nn F1 genotype: 1 NN: 2 Nn: 1 nn F1 phenotype: 1 Normal: 2 carriers: 1 Tay-Sachs sufferer or 3 normal: 1 sufferer (b) Don't start a family. (no mark) The odds are too high of having a Tay-Sachs baby. Too much heartache when dies./Very expensive to have a sick baby as there are medical costs, etc. OR Yes, try for a baby. (no mark) Only 25% chance of getting disease worth trying as odds are in your favour. Medical advances every day. Might find a cure, etc. Do IVF but only select 'healthy' embryos for implantation. (c) (i) It amplifies the DNA/makes millions of copies of the required DNA. (ii) It allows sufficient DNA purpose of DNA analysis/to be produced for testing in a short period of time, thus allowing for quicker/speedier diagnosis . IEB Copyright © 2016 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER I – MARKING GUIDELINES Page 7 of 10 QUESTION 3 3.1 3.1.1 (a) False (b) False (c) True (d) False 3.1.2 Membrane barrier prevents many micro-organisms from entering foetal blood. Membrane prevents mixing of maternal and foetal blood, which may be different types. Prevents high pressure of maternal blood from entering delicate foetal vessels. Secretes progesterone to prevent detachment from endometrium/keep anchored to uterus. (mark first 2) 3.1.3 Table comparing blood in maternal arteries and blood in the umbilical arteries. Maternal Arteries Umbilical Arteries Amt of Oxygen High Low Amt of CO2 Low High Amt of Nutrients High Low Amt of Metabolic waste Low High Table format complete. (Design of table may vary but must be comparative points. Only mark first 3. If points aren't matching up, only mark 1 side of table.) 3.1.4 (a) As the placenta detaches from the wall there will not be a fresh blood supply/oxygen supply so baby dies./Mother will lose lots of blood and could die. (b) Caesarean section involves cutting the abdominal and uterine wall to deliver baby. Vaginal delivery is non-surgical and involves the mother pushing the baby out through the vagina. (c) Birth defects/cerebral palsy can result from this condition. Parents might try to sue the doctor even though it is not his/her fault. 3.2 3.2.1 A: Birth control pill/injection/patch/implant. B: Sterilisation/Tubal ligation. C: Vasectomy/Sperm plug. D: Condom/Coitus interruptus/Abstinence/Female condom/withdrawal. E: Diaphragm/Dutch Cap/Spermicides. F: IUD/Copper T/Morning-after pill/loop/mirena. IEB Copyright © 2016 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER I – MARKING GUIDELINES Page 8 of 10 3.2.2 Type Advantage Disadvantage Usually permanent can't Sterilisation (male or Permanent – no need to reverse if change your female) take daily mind/requires operation Very safe if used Affects hormone levels so correctly/no Contraceptive Pill can have side effects/have interruption of sex/ to remember to take daily available free at clinics Protects against Can burst/leak/interrupts Condom STIs/Cheap/free at sex/reduced sensation clinics Woman can insert prior Can become dislodged Diaphragm/Dutch Cap to sex/no hormones during sex/consultation involved with DR required Not very reliable unless Spermicide Cheap and easy to use used with another method Stays in for many years Can cause bleeding or IUD/Copper T so no need for daily discomfort/Ethical issues contraception (killing of life) Don't have to remember Injection/Patch/Implant Side effects daily/woman has control/injection – free No need for Coitus interruptus Not reliable contraceptive devices Guarantee of no Abstinence No sex pregnancy or STIs 1 advantage and 1 disadvantage of 1 type of contraception (mark independently of Question 3.2.1.) Advantage of all these methods is prevention of pregnancy 3.2.3 FSH is released from pituitary gland, which causes maturation of follicle/ primary follicle to develop into a Graafian follicle. The pituitary then releases luteinizing hormone, which causes the egg to be released from Graafian follicle/ovulation. 3.2.4 (a) Sperm is just the male gamete, whereas semen includes male gametes and fluids released into the sperm ducts along the way. (b) Fertilisation involves fusion of egg and sperm whereas implantation involves the embryo becoming embedded in the endometrium. (c) Cervix is neck of uterus/junction of vagina and uterus whereas vagina is the receiving chamber open to exterior/birth canal/where penis enters to deposit sperm. (d) Conception involves the formation of a new life/fusion of egg and sperm/start of pregnancy whereas contraception is a method used to prevent formation of a new life/fusion of egg and sperm. IEB Copyright © 2016 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER I – MARKING GUIDELINES Page 9 of 10 QUESTION 4 4.1 4.1.1 107 per 100 000 population 4.1.2 Graph A shows that the effectiveness of chloroquine had dropped from 30% in 1976 to almost 0% in 1980. Graph B shows that by 1980 the number of malaria deaths was rising from 107 per 100 000 to about 120 per 100 000. 4.1.3 Within the population of Plasmodium there was variation. Some individuals were more resistant to CQ than others. The individuals that were least resistant would have died when CQ was administered leaving the more resistant variety to survive and reproduce and pass on their resistant genes to their offspring. Over time the population changed to becoming more and more resistant to CQ. (max 6) 4.1.4 (a) Asexual reproduction involves a mitotic process where new individuals give rise to new individuals without gamete formation and fusion/type of reproduction that leads to no variation. Sexual reproduction involves meiosis and the production of haploid gametes that fuse together to form a new individual/type of reproduction that leads to variation. (b) Sexual reproduction because it would result in variation through crossing over/variety in gametes, which is necessary for natural selection. Asexual reproduction leads to clones which have no variation. 4.2 4.2.1 Find fossils/Study the anatomy of fossils/date fossils/establish evolutionary relationships between fossils/classification of fossils. 4.2.2 H. naledi 4.2.3 Foramen magnum situated further forward under the skull. 4.2.4 Mrs Ples/Australopithecus africanus OR Little Foot/Australopithecus prometheus. 4.2.5 It is rich in fossils that are hominids/hominins and evidence suggests that this might have been the birthplace of modern man/ancestral hominins. 4.2.6 When Homo erectus moved up north out of Africa to Europe a group stayed behind in Africa. They evolved further and then moved up to Europe in a second wave of migration dominating all Homo species that were in Europe. IEB Copyright © 2016 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER I – MARKING GUIDELINES Page 10 of 10 4.3 4.3.1 Allopatric speciation/Separation by Geographical Isolation 4.3.2 Two ancestral populations because separated by geographical barrier. no gene flow Genetic variation/mutations occurred in each population. Environmental conditions on either side were slightly different. Natural selection occurred favouring certain genotypes, which were thus passed on to next generations. These differences became more pronounced until the two groups were so different that they were unable to reproduce. 4.3.3 Divergent evolution/Adaptive Radiation because they come from the same ancestral species but have changed to suit their specific environments. 4.3.4 (a) Behavioural isolation/their courtship was different/snapped instead of mating. (b) Organisms might breed at different times of the year so when one species is fertile the other species is not. Organisms might have developed structures that do not allow copulation between the two species. Organisms might require different environmental conditions for mating, e.g. in water or on land and so they will be unable to mate. Adaptation to different pollinators so unable to transfer pollen effectively. (Accept examples) Total: 200 marks IEB Copyright © 2016