Life Sciences Grade 12 P2 Eastern Cape Prelim 2024 Memo

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE GRADE 12 SEPTEMBER 2024 LIFE SCIENCES P2 MARKING GUIDELINE MARKS: 150 This marking guideline consists of 11 pages. Hosted by www.ecexams.co.za.

Downloaded from hlayiso.com 2 LIFE SCIENCES P2 (EC/SEPTEMBER 2024) PRINCIPLES RELATED TO MARKING LIFE SCIENCES 1. If more information than marks allocated is given Stop marking when maximum marks is reached and put a wavy line and ‘max.’ in the right-hand margin. 2. If, for example, three reasons are required and five are given Mark the first three irrespective of whether all or some are correct/incorrect. 3. If whole process is given when only a part of it is required Read all and credit the relevant part. 4. If comparisons are asked for but descriptions are given Accept if the differences/similarities are clear. 5. If tabulation is required but paragraphs are given Candidates will lose marks for not tabulating. 6. If diagrams are given with annotations when descriptions are required Candidates will lose marks. 7. If flow charts are given instead of descriptions Candidates will lose marks. 8. If sequence is muddled and links do not make sense Where sequence and links are correct, credit. Where sequence and links are incorrect, do not credit. If sequence and links become correct again, resume credit. 9. Non-recognised abbreviations Accept if first defined in answer. If not defined, do not credit the unrecognised abbreviation but credit the rest of the answer if correct. 10. Wrong numbering If answer fits into the correct sequence of questions but the wrong number is given, it is acceptable. 11. If language used changes the intended meaning Do not accept. 12. Spelling errors If recognisable, accept the answer, provided it does not mean something else in Life Sciences or if it is out of context. Copyright reserved Please turn over Hosted by www.ecexams.co.za.

Downloaded from hlayiso.com (EC/SEPTEMBER 2024) LIFE SCIENCES P2 3 13. If common names are given in terminology Accept, provided it was accepted at the national memo discussion meeting. 14. If only the letter is asked for but only the name is given (and vice versa) Do not credit. 15. If units are not given in measurements Candidates will lose marks. Marking guideline will allocate marks for units separately. 16. Be sensitive to the sense of an answer, which may be stated in a different way. 17. Caption All illustrations (diagrams, graphs, tables, etc.) must have a caption. 18. Code-switching of official languages (terms and concepts) A single word or two that appear(s) in any official language other than the learners' assessment language used to the greatest extent in his/her answers should be credited if it is correct. A marker that is proficient in the relevant official language should be consulted. This is applicable to all official languages. Copyright reserved Please turn over Hosted by www.ecexams.co.za.

Downloaded from hlayiso.com 4 LIFE SCIENCES P2 (EC/SEPTEMBER 2024) SECTION A QUESTION 1 1.1 1.1.1 B ✓✓ 1.1.2 D ✓✓ 1.1.3 A ✓✓ 1.1.4 A ✓✓ 1.1.5 B ✓✓ 1.1.6 C ✓✓ 1.1.7 C ✓✓ 1.1.8 D ✓✓ 1.1.9 C ✓✓ (9 x 2) (18) 1.2 1.2.1 Karyotype ✓ 1.2.2 Chloroplast ✓ 1.2.3 Chiasma ✓/chiasmata 1.2.4 (Blood group) O ✓ 1.2.5 Locus ✓/loci 1.2.6 Template ✓ 1.2.7 Down syndrome ✓/trisomy 21 1.2.8 (Weak) hydrogen ✓ bonds 1.2.9 Haploid ✓ (9 x 1) (9) 1.3 1.3.1 B only ✓✓ 1.3.2 A only ✓✓ 1.3.3 A only ✓✓ (3 x 2) (6) 1.4.1 Genetic engineering ✓ (1) 1.4.2 Plasmid ✓ (1) 1.4.3 Enzyme ✓ (1) 1.4.4 (a) Promotes skeletal and muscular growth ✓ (1) (b) Produces insulin ✓ (1) 1.4.5 Bacteria: - Reproduce very rapidly ✓ - Reproduce asexually ✓/by mitosis - Exists everywhere ✓ - Are simple organisms ✓ - DNA is in the form of a plasmid ✓ (Mark first TWO only) (2) 1.4.6 Attach the gene for human growth hormone to structure X ✓/plasmid (1) Copyright reserved Please turn over Hosted by www.ecexams.co.za.

Downloaded from hlayiso.com (EC/SEPTEMBER 2024) LIFE SCIENCES P2 5 1.5 1.5.1 Punctuated equilibrium ✓ (1) 1.5.2 - (Niles) Eldredge ✓ - (Stephen) Gould ✓ (2) 1.5.3 (a) 1✓ (1) (b) 2✓ (1) (c) 1✓ (1) 1.5.4 A ‒ organisms do not evolve/change ✓/remain the same B ‒ organisms rapidly evolve/change ✓ (2) 1.5.5 Biological ✓evolution (1) TOTAL SECTION A: 50 Copyright reserved Please turn over Hosted by www.ecexams.co.za.

Downloaded from hlayiso.com 6 LIFE SCIENCES P2 (EC/SEPTEMBER 2024) QUESTION 2 2.1 2.1.1 Prophase I ✓ (1) 2.1.2 (a) Centriole ✓/centrosome (1) (b) Homologous ✓ chromosomes (1) (c) Anaphase II ✓ (1) 2.1.3 6✓ (1) 2.1.4 DNA is made-up of: - deoxyribose sugar ✓ - phosphate ✓ and - nitrogenous base ✓ (Any 2) (2) 2.1.5 - DNA replication ✓* - Chromosomes which were single threads become double ✓ - each chromosome will now consist of two chromatids joined by a centromere - Doubling the genetic material ✓ Compulsory mark ✓* 1 + Any 2 (3) 2.1.6 - Part D/spindle fibre attaches to homologous chromosomes✓ - At the centre ✓/equator of the cell - Causing random arrangement ✓ of homologous chromosomes - Leading to further genetic variation ✓/new combinations (Any 3) (3) 2.2 Translation ✓* - Each tRNA carries a specific amino acid ✓ - When the anticodon on the tRNA matches ✓ - the codon on the mRNA ✓ - then tRNA brings the required amino acid to the ribosome. ✓ - Amino acids become attached to each other by peptide bonds. ✓ Compulsory mark ✓* 1 + Any 4 (5) 2.3 2.3.1 - Human embryos ✓ - Umbilical cord ✓ - Bone marrow ✓ - Placental tissue ✓ - Adult stem cells ✓ - Teeth ✓ - Skin ✓ - Amniotic fluid ✓ (Mark first TWO only) (2) 2.3.2 Macular degeneration ✓ (1) 2.3.3 4 ✓/four (1) Copyright reserved Please turn over Hosted by www.ecexams.co.za.

Downloaded from hlayiso.com (EC/SEPTEMBER 2024) LIFE SCIENCES P2 7 2.3.4 (a) Valine ✓ (1) (b) - the DNA triplet will be ACG ✓ instead of ACC - the codon will be UGC ✓ instead of UGG - the amino acid will be cysteine ✓ instead of tryptophane (3) (c) mRNA mRNA Guidelines for marking the drawing. Criteria Mark Correct caption (H) 1 Criteria One strand drawn (D) Mark 1 Heading 3 nucleotides (H) in correct positions drawn 1 (N) 1 Correct codon / 3 correct nitrogenous1 bases (C) One strand drawn (D) 1 (4) Correct codons (C) 2.4.1 - A gene ✓1-5 codons correct 2 - Guidelines for marking the drawing. located on chromosomes 1‒22 ✓/non-sex chromosomes - Two copies of the mutated gene/allele cause the condition ✓ (Any 2) (2) 2.4.2 H✓ (1) 2.4.3 - Child H inherited one recessive allele ✓/b - From each parent ✓ (2) 2.4.4 Complete ✓ dominance (1) 2.4.5 - K, L, M are heterogygous ✓/Bb - And therefore unaffected ✓ with Leigh sydrome - The dominant allele/B masks the expression of the recessive allele ✓/b (3) Copyright reserved Please turn over Hosted by www.ecexams.co.za.

Downloaded from hlayiso.com 8 LIFE SCIENCES P2 (EC/SEPTEMBER 2024) 2.5.1 Female ✓ with fragile X syndrome ✓ (2) 2.5.2 - Fragile X syndrome is caused by a dominant allele on the X- chromosome ✓/XR - Both males and females need only one dominant allele ✓/XR to be affected (2) 2.5.3 P1 Phenotype Male with x Female without fragile X ✓ fragile X ✓ Genotype XRY x XrXr Meiosis G/gametes XR , Y x Xr , Xr ✓ Fertilisation F1 Genotype XRXr ; XR Xr ; XrY ; XrY ✓ Phenotype 2 females with fragile X : 2 males without fragile X syndrome ✓ They have a 0% ✓*chance of having a son with fragile X syndrome. OR P1 Phenotype Male with x Female without fragile X ✓ fragile X ✓ Genotype XRY x XrXr Meiosis G/gametes XR , Y x Xr , Xr ✓ Fertilisation Gametes XR Y F1 X r R X X r Xr Y X r R X X r Xr Y Correct genotypes ✓ Phenotype 2 females with fragile X : 2 males without fragile X syndrome ✓ They have a 0% ✓*chance of having a son with fragile X syndrome. P1 and F1 ✓ Meiosis and fertilisation ✓ Any 6 + *1 Compulsory (7) [50] Copyright reserved Please turn over Hosted by www.ecexams.co.za.

Downloaded from hlayiso.com (EC/SEPTEMBER 2024) LIFE SCIENCES P2 9 QUESTION 3 3.1 3.1.1 There are two characteristics being crossed ✓ (1) 3.1.2 Artificial selection ✓/ Selective breeding (1) 3.1.3 To obtain a desired characteristic ✓ (1) 3.1.4 (a) bbhh ✓✓ (2) (b) BH Bh Bh bh ✓(1–3 correct) ✓✓ (All 4 correct) (2) 3.1.5 9 : 3 : 3 : 1 ✓✓ OR 9 baby hair coat with smooth hair 3 baby hair coat with curly hair ✓✓ 3 black hair coat with smooth hair 1 black hair coat with curly hair (2) 3.2 3.2.1 Non-existent by 2035 ✓ (1) 3.2.2 (a) - Habitat loss ✓ - Overfishing of their main food sardines ✓ (Mark first TWO only) (2) (b) - Breeding at different times of the year ✓ - (Species-specific) courtship behaviour ✓ (Mark first TWO only) (2) 3.2.3 (a) - Less sardines will be sold ✓/decrease in profit - leading to unemployment ✓/job losses OR - Money will be spent on other expensive sources of protein ✓ /meat - Reducing spending on other food items ✓ (Mark first ONE only) (1 x 2) (2) (b) - More sardines/food will be available ✓ - More African penguins will survive ✓/not die (Mark first ONE only) (1 x 2) (2) 3.3 - If a population of a single species becomes separated by a geographical barrier ✓ (sea, river, mountain, lake) - then the population splits into two. ✓ - There is now no gene flow between the two populations. ✓ - Since each population may be exposed to different environmental conditions✓/the selection pressure may be different - natural selection occurs independently ✓ in each of the two populations - such that the individuals of the two populations become very different from each other ✓ - genotypically and phenotypically. ✓ - Even if the two populations were to mix again ✓ - they will not be able to interbreed ✓ - The two populations are now different species. ✓ (Any 7 x 1) (7) Copyright reserved Please turn over Hosted by www.ecexams.co.za.

Downloaded from hlayiso.com 10 LIFE SCIENCES P2 (EC/SEPTEMBER 2024) 3.4 3.4.1 Australopithecus Africanus ✓ (1) 3.4.2 (a) C ✓ (1) (b) D ✓ (1) (c) A ✓ (1) 3.4.3 - Shape of B/pelvis is shorter and wider than that of primitive apes ✓ - and slightly taller and narrow compared to the human ✓ pelvis. (2) 3.4.4 - The cranium size increased ✓ in modern humans - To allow more intelligence ✓/process more information (2) 3.4.5 (a) Genetic ✓/mtDNA (1) (b) - Fossils of Australopithecus were found in Africa ONLY ✓ this suggest that ancestors of homo sapiens originated in Africa ✓ (2) 3.5 3.5.1 To determine if the individuals who made the Laetoli footprints walked using a human-like bipedalism or a more ape-like movement (bent-knee, bent-hip). ✓ (1) 3.5.2 Toe depth ✓ (1) 3.5.3 - Obtain permission from participants. ✓ - Decide on sample size. ✓ - Decide on the measuring tool ✓/materials to be used. - Decide on how results will be recorded. ✓ - Decide on time ✓/date to conduct the investigation (Mark first THREE only) (3) 3.5.4 - Investigation was done once ✓/not repeated - Sample size consists of 8 participants ✓ (2) 3.5.5 Ape-like movement ✓ (1) 3.5.6 2,2 ✓ 2 ✓ times 11 (2) Copyright reserved Please turn over Hosted by www.ecexams.co.za.

Downloaded from hlayiso.com (EC/SEPTEMBER 2024) LIFE SCIENCES P2 11 3.5.7 TYPE OF FOOTPRINT TOE DEPTH (cm) Ape-like movement 6 Human-like bipedalism 2,2 Laetoli 1,1 Criteria for marking the table. Criteria Mark allocation Correct table format (T) (Separation of columns) 1 Column headings (H) 1 Data entered (E) 1–2 data sets are entered correctly 1 All 3 data sets are entered correctly 2 (4) [50] TOTAL SECTION B: 100 GRAND TOTAL: 150 Copyright reserved Please turn over Hosted by www.ecexams.co.za.