Life Sciences Grade 12 IEB Paper 1 2017 Memo

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE EXAMINATION NOVEMBER 2017 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 © 2017

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER I – MARKING GUIDELINES Page 2 of 9 QUESTION 1 1.1 COLUMN A COLUMN B [E] Characterised by a high birth rate and a A Predation high death rate. B Primary succession [F] Number of organisms per cubic metre. C Carrying capacity [A] An ecological relationship where one organism hunts and kills another organism D Resource partitioning for food. E Less-developed [H] Growth curve characterised by rapid country increases in number usually followed by extinction phase. F Population density [C] The maximum number of individuals an G Emigration environment can sustain. H Geometric [I] Flora and fauna in an ecosystem. I Community [L] Development of new vegetation after a fire. J More-developed [D] Organisms sharing an ecosystem in such a country way that they reduce competition. K Quadrat [K] A method of population estimation. L Secondary [G] A population parameter that has no effect in succession a closed population. 1.2 Question 1.2.1 1.2.2 1.2.3 1.2.4 1.2.5 1.2.6 Answer B D A C A B 1.3 Statement A, B or C 1.3.1 Alcohol is also responsible for low birthweight in C newborn babies 1.3.2 Smoking during pregnancy increases the chance of low A birthweight babies. 1.3.3 All low birthweight babies have mothers who smoke. B 1.3.4 There are more babies born whose birthweight is 2 000– A 2 499 g than babies whose birthweight is 1 000–1 499 g. 1.3.5 Smoking during pregnancy can cause brain damage to C the child. IEB Copyright © 2017 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER I – MARKING GUIDELINES Page 3 of 9 1.4 1.4.1 1. Tail/contractile fibres/axoneme/flagellum 2. Middle piece/neck/mid piece 3. Head 4. Acrosome 5. Nucleus 6. Mitochondrion (or plural) Mitochondrial spiral or coil 1.4.2 1 and 6/2 1.4.3 To swim to/reach/move to egg quickly / whilst egg/sperm are viable 1.4.4 (a) Water/Saline solution/fructose/no caffeine/mucous/alkaline fluid/fluid from reproductive accessory glands (b) To compare (implied) with experiment to ensure that it is the caffeine/ independent variable causing the effect. 1.4.5 (a) Caffeine (or no caffeine/amount or concentration) (b) Sperm motility (c) Number of sperm/amt of fluid/person donating sperm/time in petri dish/ age or freshness of sperm, pH, etc. 1.4.6 The acrosome needs to burst to dissolve membrane so that nucleus can enter/penetrate/combine with the ovum/fuse with egg 1.5 1.5.1 Item Term Answer 1. TT Heterozygous B 2. Tt 1. Different forms of the same gene Alleles A 2. Identical forms of a gene 1. Non-coding DNA of an organism Genome D 2. Photograph of all the chromosomes 1. Homologous chromosomes are different in size Autosome B 2. Homologous chromosomes are the same size 1. Only expressed in phenotype if in homozygous form Recessive C 2. Suppressed by a dominant gene 1.5.2 (a) P (any letter capitalized) = allele for Polydactyly/affected and p (lower case of same letter) = allele for normal/unaffected (any letter but must be cap for Polydactyly) (b) Individual Genotype 1 pp 2 Pp 4 Pp IEB Copyright © 2017 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER I – MARKING GUIDELINES Page 4 of 9 (c) Individual Gender Phenotype 3 Male Polydactyly/affected 5 Female Normal/unaffected (d) A mutation on a non-sex (1-22) chromosome which suppresses a normal/recessive gene expression. /can be expressed if only 1 gene is present/expressed in the heterozygous (e) P genotypes Pp × pp p p (method mark) (1 mistake =1, 2 or more P Pp Pp =0) gametes – (method p pp pp mark) F1 genotype 1 Pp : 1 pp (accept percentages and fractions) (assume the 1) (if only 1:1 can get mark if Punnet square is correct) F1 phenotype 1 Polydactyly /affected : 1 normal/unaffected (assume the 1) 1.6 1.6.1 P = MC/R = 23 × 29 / 11 = between 60 – 61 (60.6 accepted) 1.6.2 Only mark first 3 Make sure tags don't harm rats Make sure tags are securely on/can't fall off Make sure tags are not too conspicuous/affect recapture or predation Tags don’t affect motility Tags don’t affect behaviour Technician wears gloves to not leave human smell behind Technicians need to protect themselves from picking up disease/ being bitten 1.6.3 (a) A – very rapid steep/exponential/accelerating growth as there are abundant resources/name resource/favourable conditions for reproduction/below carrying capacity/ little environmental resistance. B – slower growth/decelerated as resources are starting to be limiting or name one resource/ approaching carrying capacity./ environmental resistance increasing/ conditions unfavourable for reproduction/increased competition (b) food/space/build-up of toxins/disease/predation/shelter/ water/competition IEB Copyright © 2017 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER I – MARKING GUIDELINES Page 5 of 9 QUESTION 2 2.1 2.1.1 DNA unwinds H bonds break /sugar-phosphate backbones move apart. Free (RNA ) nucleotides link onto corresponding bases S-P (backbone) links/joins up by dehydration synthesis. mRNA detaches from DNA. If continue to describe translation max 3 2.1.2 mRNA moves to ribosome where codons are read tRNA links anticodon onto corresponding codon bringing with it a specific amino acid link up to form peptide bonds of a protein thus the sequence of codons determines the sequence of amino acids. 2.1.3 Tyr – Pro – Asp (If sequence is incorrect -1) 2.2 2.2.1 Ligase 2.2.2 Yeast reproduces quickly and thus makes many copies of the desired gene Cheap Simple eukaryotic cell-similar to humans Readily available Unicellular so simple mitotic division Asexually – offspring identical 2.2.3 DNA which has had foreign DNA/DNA from another organism inserted into it / DNA which has had foreign genes mixed with other genes. 2.2.4 HB antigen (desired) gene isolated/extracted Extract plasmid Host DNA plasmid cut open Insertion of HB gene into host DNA plasmid (Recombinant) plasmid put into yeast cell Yeast cell cultivated in fermentation tank copies made of yeast/ yeast reproducing HB antigen extracted from tank/HB antigen produced /HB vaccine formed Any order/sequence accepted 2.3 2.3.1 Cells blood/DNA/saliva/sperm/from criminal left at scene DNA Profile created DNA tested/DNA fingerprint produced Match to DNA in database/suspect 7−8 2.3.2 6 9 × 3 000 = 180 –270 100 2.3.3 Using DNA technology increases the success rates in the fight against crime/suspected arrests/suspect convicted/suspects identified. If question or aim (max 1) 2.3.4 (17–19%) – (6–9%) = 8–13% 2.3.5 SUPPORTING - increase success rate in fight against crime IEB Copyright © 2017 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER I – MARKING GUIDELINES Page 6 of 9 - will prevent reoffenders from going undetected - will allow criminals to be identified from crime scene evidence paternity/lost children/ identification of dead/establish ancestry (first 2) OPPOSING - very expensive - invasion of privacy /infringe on individual rights (must only refer to collection process) - other, more pressing needs in the country - technical process compromised/human error/ contamination - hacking into system to swap identities (first 2) 2.3.6 DNA can be used to put you in/get you out of jail/in criminal court. DNA can be opened and altered/DNA can be unlocked by technology/DNA can open gates to understanding / 2.4 b, c, d [both correct (2)/only 1 correct (1)/2 correct plus 1 incorrect (1)/3 correct plus 1 incorrect (1)] (include a = subtract 1 if more than 2 options given) QUESTION 3 3.1 3.1.1 A group of organisms of the same species occupying a definable area close enough for random interbreeding. 3.1.2 Shark nets /Baited hooks (culling) /Poaching /Overfishing / Limited genetic diversity. 3.1.3 Reduction in smaller fish causing decline in the Cape Seal population which is prey of great white shark. 3.1.4 Loss of hybrid vigour as no new genes coming into gene pool. Shrinking gene pool/small gene pool/become genetically similar This makes them more prone to disease/genetic mutations finding expression. Inability to adapt to changing environment 3.1.5 Census needs to count each individual or mark recapture requires a sample, which is very hard to find as sharks live deep under sea, so difficult to find and have large territory so impossible to cover whole area. Move fast/time consuming/mark recapture less expensive or resource/reliability of counting because no tagging IEB Copyright © 2017 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER I – MARKING GUIDELINES Page 7 of 9 3.1.6 Declare protected areas where no fishing allowed. Lift shark nets and find other methods to protect bathers. Introduce new individuals to existing populations to allow gene flow. Start shark breeding programmes. Start seal breeding programmes Greater consequences for shark fishing - legislation Education programmes about extinction (Mark only first 2) 3.2 3.2.1 Predation/Predator-prey 3.2.2 (a) A dotted line (b) Lower numbers and graph lags behind prey graph or prey has higher numbers and peaks/drops before predator 3.3 3.3.1 (a) 1-2 billion (b) 10–11 billion 3.3.2 Increase food production (from GMO) improved agriculture / food preservation Find cures for disease/better medical care vaccines Build high-rise buildings Area cleared Better sanitation Desalination of water Better utilisation of non-renewable energy sources 3.3.3 We need to slow down population growth before it is too late/ If we continue to grow at such a rapid rate/exponentially otherwise we will hit extinction phase/many people will die/we will not be able to provide food for everyone. 3.4 3.4.1 r-strategist 3.4.2 By producing so many young there is a good chance that at least some will survive (No parental care) so parents can protect/feed themselves better ensuring survival Less energy expenditure in developing offspring so can invest energy in other survival strategies/reproduce again (First 2) 3.5 3.5.1 Non-coding DNA because coding DNA is almost identical or non- coding is unique as it codes for essential hormones/enzymes etc. whereas non-coding DNA has no purposeful sequence 3.5.2 DNA sample extracted from horns  PCR to amplify samples of DNA DNA profile/fingerprint created for rhino  compared to rhODIS/rhino DNA database  if match is found then criminals can be arrested/criminals convicted or used in court IEB Copyright © 2017 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER I – MARKING GUIDELINES Page 8 of 9 QUESTION 4 4.1 4.1.1 Letter of Name of flower part Letter of pear part flower part G none/blank/ A Petal corolla not present C Ovule/ovum/egg F Ovary/ovary wall/ E D receptacle/carpals 4.1.2 (a) Genetically Modified Organism genetically modified (b) They would need to locate/the gene that coded for the enzyme, that caused the browning process and the prevent expression silence/remove of the gene/silence the gene/ deactivate the gene. 4.2 4.2.1 FSH 4.2.2 follicle ruptured/Ovulation occurred on day 14 so the follicle no longer contained the ovum (egg) 4.2.3 (a) From days 5–14 (25) the follicle secretes oestrogen From days 15–25 the follicle secretes progesterone (First 2 hormones marked) (b) Oestrogen – causes endometrium to build up/development of secondary sexual characteristics or specific one/stimulates release of LH/inhibit FSH Progesterone – maintenance of endometrium/vascularisation and glandularisation of endometrium prepares uterus for pregnancy. Inhibits FSH and LH. 4.3 4.3.1 They allow for erection of penis, which enables sperm to be placed deep inside female body increasing chances of successful fertilisation. 4.3.2 Component Importance Fluid/water Allow sperm to swim Sugar/Sucrose/fructose Provide energy for sperm to swim (seminal fluid) Alkaline/buffer/mucous Neutralise vaginal acidity/acidity in urethra (prostate fluid) Lubricant/mucous (cowpers/ Allow penis to penetrate vagina/ viscosity – pre-ejaculatory fluid) sperm stick IEB Copyright © 2017 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER I – MARKING GUIDELINES Page 9 of 9 Sperm/gametes Provides genetic material for fertilisation/ to fuse with ovum (egg)/carry male chromosomes prostaglandin Muscular contraction Enzymes/ protein Penetrate Prostate fluid Neutralise vaginal acidity/acidity in urethra Cowpers fluid Allow penis to penetrate vagina/ viscosity – sperm stick Seminal fluid Provide fluid and energy for sperm to swim Vitamin and minerals Nourish the sperm 4.4 4.4.1 Hormone 1: Glucagon Hormone 2: Insulin 4.4.2 Islets of Langerhans in the Pancreas 4.4.3 Hormone 2 causes glucose in blood to be absorbed by liver/body cells and converted into glycogen lowers blood sugar level 4.4.4 (a) Type 2 the cells are insulin resistant whereas in Type 1 the body does not produce insulin insulin dependant / beta cells are destroyed/ not enough insulin (b) The way that people live – their habits e.g. Poor diet/lack of exercise causes this type to develop Total: 200 marks IEB Copyright © 2017