Life Sciences Grade 12 Eastern Cape June 2025 Memo (English)

NATIONAL SENIOR CERTIFICATE GRADE 12 JUNE 2025 LIFE SCIENCES MARKING GUIDELINE MARKS: 150 This marking guideline consists of 11 pages.

2 LIFE SCIENCES (EC/JUNE 2025) PRINCIPLES RELATED TO MARKING LIFE SCIENCES 1. If more information than marks allocated is given . 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. 13. If common names are given in terminology Accept, provided it was accepted at the national standardisation meeting. 14. If only the letter is asked for but only the name is given (and vice versa) Do not credit. Copyright reserved Please turn over

(EC/JUNE2025) LIFE SCIENCES 3 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

4 LIFE SCIENCES (EC/JUNE 2025) SECTION A QUESTION 1 1.1 1.1.1 D 1.1.2 B 1.1.3 B 1.1.4 A 1.1.5 B 1.1.6 D 1.1.7 D 1.1.8 B 1.1.9 C (9 x 2) (18) 1.2 1.2.1 Peripheral nervous system 1.2.2 Multiple sclerosis 1.2.3 Interphase 1.2.4 Precocial development 1.2.5 Convex lenses 1.2.6 Centriole /centrosome 1.2.7 Retina 1.2.8 Synapse (8 x 1) (8) 1.3 1.3.1 Both A and B 1.3.2 A only 1.3.3 B only (3 x 2) (6) 1.4.1 (a) Menstruation (1) (b) Ovulation (1) 1.4.2 (a) LH /Luteinising hormone (1) (b) Progesterone (1) 1.4.3 (a) Ovarian cycle (1) (b) Uterine cycle (1) 1.4.4 Ovary (1) 1.4.5 (a) Ovum (1) (b) Endometrium (1) Copyright reserved Please turn over

(EC/JUNE2025) LIFE SCIENCES 5 1.5 1.5.1 Cytoplasm (1) 1.5.2 (a) Peptide (1) (b) mRNA / messenger RNA/ messenger Ribonucleic acid (1) 1.5.3 (a) Anticodon (1) (b) tRNA / transfer Ribonucleic acid (1) (c) Ribosome (1) 1.5.4 ACC (1) 1.5.5 2 Amino acid (2) TOTAL SECTION A: 50 Copyright reserved Please turn over

6 LIFE SCIENCES (EC/JUNE 2025) QUESTION 2 2.1 2.1.1 - An arrangement of black bars/lines/stripes representing DNA fragments of a person OR - The pattern of the bars that indicate the sequence of bases on a DNA strand. OR - A set of genetic characteristics that results from forensic DNA analysis of several DNA markers. (2) 2.1.2 B (1) 2.1.3 - A child received DNA from both parents - The DNA profiles of the mother, child and the possible father are determined - A comparison of the DNA bands of the mother and the child is made - DNA bands - then the possible father is the biological father - then the possible father is not the biological father (6) 2.1.4 - To identify individuals from their remains - To identify family relationships other than paternity, e.g. siblings or cousins - To test for the presence of specific alleles/ genes that cause a genetic disorder - To establish matching tissues for organ transplants (Any 2 x 1) (2) 2.2 2.2.1 45 (1) 2.2.2 Gonosomes /sex chromosomes (1) 2.2.3 - Edwards syndrome have three copies of chromosome 18 instead of the usual two - Down syndrome have three copies of chromosome 21 instead of the usual two (2) Copyright reserved Please turn over

(EC/JUNE2025) LIFE SCIENCES 7 2.2.4 - During Anaphase I / II - Non-disjunction occurs - in chromosome pair 18 /chromatids of chromosome 18 which - will lead to the formation of a gamete with an extra chromosome number 18 /2 chromosomes number 18 - If this gamete fuses with a normal gamete - a zygote with 3 chromosomes number 18 will form - The fusion between an abnormal gamete (24 chromosomes) and a normal gamete (23 chromosomes) may lead to Edwards syndrome (Any 6 x 1) (6) 2.3 2.3.1 Co-dominance (1) 2.3.2 - The alleles are equally dominant - both are expressed in the phenotype (2) 2.3.3 P1 Phenotype Speckled feathersx Speckled feathers Genotype BW x BW Meiosis G/gametes B W x B W Fertilisation F1 Genotype: BB ; BW ; BW; WW * Phenotype: 1 black : 2 speckled : 1 white * P1 and F1 Meiosis and fertilisation *two compulsory marks and Any 4 OR P1 Phenotype Speckled feathers x Speckled feathers Genotype BW x BW Meiosis G/gametes B , W x B, W Fertilisation Gametes B W F1 B BB BW W BW WW Correct gametes Correct genotypes * Phenotype 1 black : 2 speckled : 1 white * P1 and F1 Meiosis and fertilisation *two compulsory marks and Any 4 (6) Copyright reserved Please turn over

8 LIFE SCIENCES (EC/JUNE 2025) 2.4 2.4.1 (a) Medulla oblongata (1) (b) Corpus callosum (1) 2.4.2 A (1) 2.4.3 Behind and below the cerebrum (2) 2.4.4 (a) - Part A/ cerebrum which receives and interprets sensations from sense organs - Part A/ cerebrum was not injured (2) (b) - The learner (occasionally) experience difficulty balancing when kicking - due to no coordination of voluntary movements by cerebellum / decreased muscle tone (2) 2.5.1 (a) Semi-circular canals (1) (b) Tympanic membrane / eardrum (1) 2.5.2 (a) F (1) (b) B (1) 2.5.3 Part C/ Oval window transfers pressure wave to the inner ear. / Receives vibrations from the ossicle/ middle ear Part E/ Round window receives pressure waves from the inner ear / transfers pressure waves to the middle ear / eustachian tube (2) 2.5.4 Organ of Corti /hair cells (1) 2.5.5 - Air will not be move in /out of middle ear - to equalise pressure on both sides of the tympanic membrane - Tympanic membrane/ossicles may not vibrate freely - This may lead to the tympanic membrane bursting - and therefore, could lead to hearing loss /deafness (Any 4 x 1) (4) [50] Copyright reserved Please turn over

(EC/JUNE2025) LIFE SCIENCES 9 QUESTION 3 3.1 3.1.1 - Amniotic fluid (1) 3.1.2 - Shock absorber, protects the foetus from mechanical damage - Thermoregulation prevents extreme temperature changes - Moist environment to prevent desiccation - Free movement within the womb, promoting muscular and skeletal development - Environment provides the medium in which the foetus moves /breathes / swallows (Any 1 x 2) (2) (Mark first ONE only) 3.1.3 - After implantation the chorion develops many finger-like outgrowths - called chorionic villi - The endometrium - together with the chorionic villi forms the placenta - The umbilical artery and the umbilical vein develops inside a hollow tube to form the umbilical cord between the foetus and the placenta (Any 6 x 1) (6) 3.1.4 Increased progesterone and oestrogen concentrations: - inhibits the pituitary gland from - secreting FSH and - secreting LH - therefore, no Graafian follicle will develop - No ovulation will take place / No ovum will be present for fertilisation (Any 4 x 1) (4) 3.1.5 - The Fallopian tube is unable to provide the space - and there is no endometrium /blood supply - to provide nutrients /oxygen OR remove waste products - in order for the embryo to develop (4) 3.2 3.2.1 - Breast development - Start of menstruation - Widening of the hips - Growth of pubic hair - Growth of underarm hair (Any 2 x 1) (2) (Mark first TWO only) 3.2.2 - Under the influence of testosterone - diploid cells in the seminiferous tubules of the testes - undergo meiosis - to form haploid sperm cells (4) Copyright reserved Please turn over

10 LIFE SCIENCES (EC/JUNE 2025) 3.3 3.3.1 - sperm and ova are in close contact to increase the chance of fertilisation taking place - gametes not exposed to predators / water currents / desiccation to increase chance of fertilisation - does not rely on water for gamete transport increase possibility of fertilisation taking place - reduces the risk of gametes being lost or wasted, increasing chance of fertilisation (Any 2 x 2) (4) 3.3.2 parental care increases the chances of offspring survival (1) 3.4 - Less light would enter the eye / pupil - Less light would fall on the retina / receptors would be stimulated less - The image would not be clear (3) 3.5 3.5.1 Wheat without insect poison gene that was grown in the field (1) 3.5.2 Ensuring that any differences in yield are due to genetic modification ONLY /and not external factors (1) 3.5.3 (70 50) = 20 (arbitrary units) (2) 3.5.4 - Non-GM plants may be better suited to the local environment (specific climates, soil, or farming practices), while GM plants may not always be as well-suited to local conditions. - Non-GM plants may be better equipped to handle stresses (like drought, competition with weeds, nutrient limitations) while GM plants may not always be as well-suited to local conditions. - Non-GM plants may maintain more natural or symbiotic relationships with beneficial soil organisms, giving them an advantage in nutrient uptake and overall health. - Non-GM plants contributes to biodiversity and help maintain a balanced ecosystem - GM plants, especially, can disrupt local ecosystems by affecting non- target insects and other organisms - GM crops can lead to the rise of weeds that are resistant to pesticides (insect poison) - decreasing their effectiveness. (Any 1 x 2) (2) 3.5.5 Insect poison reduces insect populations numbers and biodiversity. (1) 3.6 3.6.1 To determine the relationship between different blood groups and risk to specific diseases. (2) 3.6.2 - Determine the sample size - Decide on the age-group of the participants - Decide on diseases to be tested for (Any 2 x 1) (2) (Mark first TWO only) 3.6.3 500 individuals participated (1) Copyright reserved Please turn over

(EC/JUNE2025) LIFE SCIENCES 11 3.6.4 Guideline for assessing graph: CRITERIA MARK Bar graph is drawn (T) 1 Caption of the graph includes both variables (C) 1 Correct labels on the X-axis and Y-axis with correct unit on the Y-axis (L) 1 Correct scale for Y-axis and bars of equal width and spaces for X-axis (S) 1 Plotting (P) correctly done for: 1 3 blood types 1 All 4 required blood types 1 (6) - Bar graph or line graph drawn Lose marks for type of graph and scale - Transposed axes: Can get full credit, if axes labels are also swapped and bars are horizontal. If labels are not corresponding, then lose marks for labels and scale - Check that the plotting is correct for the given labels [50] TOTAL SECTION B: 100 GRAND TOTAL: 150 Copyright reserved Please turn over