Life Sciences Grade 12 Paper 2 Free State June 2025 Memo

education Department of Education FREE STATE PROVINCE GRADE 12 LIFE SCIENCES P2 JUNE 2025 TOTAL: 150 MARKING GUIDELINES These marking guidelines consist of 10 pages. Copyright reserved Please turn over

Life Sciences 2 June 2025 Grade 12 Paper 2 Marking Guidelines PRINCIPLES RELATED TO MARKING LIFE SCIENCES abe 10. 14: 12: 13. 14. 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. If, for example, three reasons are required and five are given Mark the first three irrespective of whether all or some are correct/incorrect. If whole process is given when only a part of it is required Read all and credit the relevant part. If comparisons are asked for but descriptions are given Accept if the differences/similarities are clear. If tabulation is required, but paragraphs are given Candidates will lose marks for not tabulating. If diagrams are given with annotations when descriptions are required Candidates will lose marks. If flow charts are given instead of descriptions Candidates will lose marks. 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. 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. Wrong numbering If answer fits into the correct sequence of questions but the wrong number is given, it is acceptable. If language used changes the intended meaning Do not accept. Spelling errors If recognisable, accept the answer, provided it does not mean something else in Life Sciences or if it is out of context. If common names are given in terminology Accept, provided it was accepted at the memo discussion meeting. If only the letter is asked for but only the name is given (and vice versa) Do not credit. Copyright reserved Please turn over

Life Sciences 3 June 2025 Grade 12 Paper 2 Marking Guidelines 15. If units are not given in measurements Candidates will lose marks. Memorandum 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 learner's 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

Life Sciences 4 June 2025 Grade 12 Paper 2 Marking Guidelines SECTION A QUESTION 1 ab 11s Bvv 13152 Bvv 1.1.3 Dvv 1.1.4 C vv a a a} Cvv 1:1:6 Bvyv AST Bvv 1.1.8 A vv (8x2) (16) 2 Interphase v 20 12:2 Haemophiliav 1.2.3 DNA profilingY 1.2.4 Centriole / CentrosomeY 1.2.5 (Weak) hydrogen bonds¥ 1.2.6 HomozygousY¥ 1.2.7 Ribosev (1x7) (7) 1.3 1:31 A only¥v 1.3.2 Nonev v 1.3.3 Bonlyvv (3 x 2) (6) 1.4 1.4.1 a) YY (1) b) Xv (1) 1.4.2 Double helixy (1) 143 ACTG(VV) (2) 1.4.4 MitochondriaY (2) ChloroplastY (1) 1.4.5 Thyminev /(T) (1) 1.4.6 Fourv/4 (9) Copyright reserved Please turn over

Life Sciences 5 June 2025 Grade 12 Paper 2 Marking Guidelines 1.5 1:5:1 Dihybrid (crossing) ~ (4). 1.5.2 (a) BBhhy ¥ (2) (b) bhY/ bh bh bh bh (1) (c) Brown hair colour and short hairy ¥ (2) (6) 1.6 16.1 4/Foury (1) 1.6.2 2/1 Two : (1) 1.6.3 - They are the same/ similar size/length. - They have the same/ similar shape. ¥ - They have genes for the same characteristics. ¥ - They have alleles of a specific gene on the same locus. ¥ - They have centromeres in the same position. VW (2) (Mark first TWO only) (Any TWO) (1) 1.6.4 Centromerev (1) 1.6.5 Diploid cellv (6) TOTAL SECTION A: (50) QUESTION 2 2.1. -It is the arrangement of the (complete set of an individual’s) 4 chromosomesY -According to the number and shapev of the chromosomes. (2) Autosomes ¥ (1) 2:1: 2 Femalev ¥ (2) 2.1. | -3 chromosomesv / an extra chromosome 3 - at position number 21 ¥ (2) (7) 2.1 4 - The factors/alleles that control a characteristic separate Vv - during meiosis ¥ - so that only one factor/allele is present in each gamete ¥ (3) 2:2 Translation’ (1) RibosomeY (1) 2.3. a) Peptide Bondy (1) 1 b) tRNAV / transfer RNA (1) Copyright reserved Please turn over

Life Sciences 6 June 2025 Grade 12 Paper 2 Marking Guidelines 2.3. 3v/three (1) 2 a) Tryptophany (1) 2.3. 3 b) ACCYY (2) c) 2v (1) 2.3% 4 - The codon on the mRNAY - will change from UUA to UUGY 2:3: - The anticodon on the tRNA will bring the same amino acid v/ 5 Leucine to the ribosome - The sequence of the amino acids would not change ¥ - Therefore, there will be no effect on the protein formedv/ same protein will form (5) (14) 2.4 - The DNA double helix unwindsY and - (the double strand) unzips/weak hydrogen bonds breakY - to form two separate strandsY - One strand is used as a templateY - To form mRNAY - Using free RNA nucleotidesv from the nucleoplasm - The mRNA is complementary to the DNA “/A compliments U,G compliments C Any 6 (6) 2.5. Striped fury (1) - In Breeding pair 1v 2:5: - both parents are spotted fury /none of the parents are striped fur 2 - but striped fur appears in the phenotype of the offspringyY OR - In cross 1¥ -The ratio spotted fur to stripe fur is 3:1” -The smaller portion represents the recessive alle striped fur Vv (3) A gene mutation is a change in the sequence of nucleotides in a Copyright reserved Please turn over

Life Sciences a6 Grade 12 Paper 2 Marking Guidelines gene/ DNAYY Law of dominancev P1 Phenotype : Spotted fur x Spotted fury Genotype Nn x Nnv Meiosis G/gametes N x N nv Fertilization F1 Genotype NN, Nn, Nn, nn ¥ Phenotype ratio: 3 Spotted: 1 striped *v P1 and Fiv June 2025 (2) (1) Meiosis and fertilization’ *Compulsory 1 + Any 5 OR Pi Phenotype Spotted fur x Spotted fur V Genotype Nn x Meiosis G/gametes N, on x Gametes | N n Fertilisation N NN Nn 1 Mark tor correct gametes 1 Mark tor correct Genotypes F; Genotype NN, Nn, Nn, nn Phenotype 3 Spotted fur: 1 Striped fur v* Pi and Fi¥ Meiosis and fertilisation V *Compulsory 1 + Any 5 Copyright reserved (6) (13) Please turn over

Life Sciences 8 June 2025 Grade 12 Paper 2 Marking Guidelines 26.1 2v (1) 26.2 5-X®Xv¥v (2) 2.6.3 - Males have only one X chromosomev/ XY sex chromosomes - If this chromosome carries the recessive allelev/ (X‘) - the male will suffer from Lesch-Nyhan syndrome ¥ - Females have two X chromosomesv/XX and - will only suffer from Lesch-Nyhan syndrome when they carry two recessive alleles on both X chromosomesv /(X' X') - A dominant allele on one of the X-chromosomes will mask the effectY Any 4 (4) (7) Total Queston 2 [50] QUESTION 3 3.1.1 FatherBY (1) 3:12 - Allthe DNA profile bars/bands of the children that do not match the motherv, match the DNA profile bars/bands of Father BY OR - All DNA profile bands of the mother and Father BY - match all the children’s DNA profile bandsv (2) 3.1.3 Child 1 and 2vv (2) 3.1.4 - Blood groups cannot identify with certainty who is the father v/ 3.1.5 blood groups can only eliminate men who are not the father - Because many males have the same blood group. ¥ - Each person’s DNA profile is unique. ¥ (3) - To identify organisms/dead people from their remainsv Copyright reserved Please turn over

Life Sciences Grade 12 Paper 2 9 June 2025 Marking Guidelines To test for the presence of specific alleles v for genetic conditions/Identification of genetic disorders To establish matching tissues for organ transplantsY Identification of suspects in a crime ¥ Tracing missing persons ¥ (Mark first two only ) Any 2 (2) 3.1.6 - Mark the samples clearly“ to ensure that the samples are not mixed upY - Wear a mask and glovesY ,DNA must not get contaminatedv - Use new and clean/sterilized apparatusY to ensure no contamination from previous tests. ¥ - Check the access of persons/Only authorized persons may have accessv so that no one can tamper with the samples. (Mark first ONE Only) (Any 1 x 2) (2) (12) 3.2.1. Anaphase 1 (1) 3.2.2. - Chromosome of (homologous pair) is being pulled to the opposite poles ¥ (1) 3.2.3 a) CentrioleY (1) b) Spindle fibery (1) 3.2.4 3v/three (1) (5) 3.3 Mitosis Meiosis Mitosis occurs in body | Meiosis occurs in sex cells¥ cellsv Both karyokinesis and cytokinesis occurs once.v Both karyokinesis and cytokinesis occurs twice.~ Two daughter cells are formed.v Four daughter cell are formed.v Daughter cells are genetically identical to one another and to the parent cellv¥ Daughter cells are genetically different from each other and from the parent cellv Chromosome number remains constantv Chromosome number is halvedv Crossing over does not occurY Crossing over occursY (Mark first THREE only ) Copyright reserved ( Any 3X2) Please turn over Y for TABLE (7)

Life Sciences 10 June 2025 Grade 12 Paper 2 Marking Guidelines 3.4.1 3.4.2 3.4.3 3.4.4 3.4.5 3.5.1 3.5.2 3.5.3 3.5.4 3.6.1 3.6.2 What is the effect of temperature on the frequency of meiotic recombination in barley plants?v Vv (2) a) Temperaturey (1) b) Frequency of meiotic recombinationY (1) - Same amount of waterY - Same light intensityY - Same barley plant varietyY - Same precise method of counting ¥ (Mark first THREE only) ( Any 3) (3) - Genetic material is exchanged.v (1) -The production of haploid gametes¥ - It maintains a constant chromosome number from one generation to the next.v - Itincreases genetic variation Vv (any 2) (2) (Mark first TWO only) (10) Undifferentiated cells that can develop into any other type of cellVv (2) MitosisY (1) -It can help to replace and repair damaged cells V after an injury or infection - Embryonic stem cells can differentiate into any cell typev - Some diseases and disorders can also be treated. v/ Leukemia and Parkinsons can be treated (Mark first TWO only) (Any 2) (2) Bone marrow /blood/heart/adipose tissue/brain (Mark first ONE only) (Any 1) (1) (6) - Blood groups/the gene for blood groups is controlled by three allelesv/ I*, 15, i - Each person can only inherit two allelesv/One allele from each parent Vv - The I and I allele are dominant v - over the i allele ¥ - The combination I*i and I*I produce blood group AY - The combination |°i and I°I° produces blood group BY - The combination II? produces blood group ABY - The combination ii produces blood group OY (6) - The Mother is heterozygous for blood group Av / I*i Copyright reserved Please turn over

Life Sciences 11 June 2025 Grade 12 Paper 2 Marking Guidelines - Ther father is heterozygous for blood group Bv/ I°i - The child is homozygous for blood group Ov /ii (4) - And receive the recessive allelew/i form each parent a [50] TOTAL SECTION B: 100 GRAND TOTAL: 150