Life Sciences Grade 12 P1 Eastern Cape Prelim 2024 Memo

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE GRADE 12 SEPTEMBER 2024 LIFE SCIENCES P1 MARKING GUIDELINE MARKS: 150 This marking guideline consists of 10 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 are 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 the 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 provincial memo discussion 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 Hosted by www.ecexams.co.za.

Downloaded from hlayiso.com (EC/SEPTEMBER 2024) LIFE SCIENCES P1 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 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 A ✓✓ 1.1.2 B ✓✓ 1.1.3 C ✓✓ 1.1.4 A ✓✓ 1.1.5 C ✓✓ 1.1.6 B ✓✓ 1.1.7 D ✓✓ 1.1.8 A ✓✓ 1.1.9 C ✓✓ (9 x 2) (18) 1.2 1.2.1 Receptor ✓ 1.2.2 Chorion ✓ 1.2.3 Effector ✓ 1.2.4 Vasodilation ✓ 1.2.5 Concave ✓ 1.2.6 Mammary ✓ 1.2.7 Retina ✓ 1.2.8 Hypothalamus ✓ 1.2.9 Synapse ✓ / synaptic cleft (9 x 1) (9) 1.3 1.3.1 A only ✓✓ 1.3.2 None ✓✓ 1.3.3 Both A and B ✓✓ 1.3.4 A only ✓✓ (4 x 2) (8) 1.4.1 (a) D ✓ ‒ Cerebellum ✓ (2) (b) A ✓ ‒ Cerebrum ✓ (2) (c) B ✓ ‒ Medulla Oblongata ✓ (2) 1.4.2 - Vertebrae ✓ Prevent mechanical injury ✓ - Cerebral spinal fluid ✓ Cushioning the spinal cord acting as a shock absorber ✓/ prevent friction - Meninges ✓ Membranes hold the spinal cord in place ✓/ produce cerebral spinal fluid (Mark first TWO only) (Any 2 x 2) (4) Copyright reserved Please turn over Hosted by www.ecexams.co.za.

Downloaded from hlayiso.com (EC/SEPTEMBER 2024) LIFE SCIENCES P1 5 1.5 Diagram of sensory neuron Cell body Nucleus Cytoplasm Dendrite Myelin Axon sheath Axon Terminal Marking guideline: ✓ (T) Suitable title ✓✓✓ (L) Labels (Any 3) ✓ (D) Correct drawing (sensory neuron) (5) 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) SECTION B QUESTION 2 2.1 2.1.1 10 ✓ x 84 000 ✓=8 400 babies ✓ (3) 100 2.1.2 (a) - Thick plastic bag ✓ Encloses (protects) the developing foetus until delivery ✓ (Mark first ONE only) (2) (b) - Oxygenator ✓ Allows for gaseous exchange ✓ OR - Intravenous bag ✓ Provides nutrients ✓ (Mark first ONE only) (Any 1 x 2) (2) 2.1.3 - The developing foetus (organs) is allowed to continue developing/ ✓ Giving the organs sufficient time - its normal development ✓/ to develop fully/ for optimal development - Scientists can determine when the gestation period is over ✓/when to deliver the baby (3) 2.1.4 - Human foetuses could possibly be lost / destroyed ✓ - Acquiring consent from regulatory bodies ✓/parents - Fully informing donor parent(s) about the risks ✓ - Contrary to religious observances ✓ (Mark first TWO only) (Any 2 x 1) (2) 2.2 2.2.1 Internal ✓ fertilisation (1) 2.2.2 The male releases semen inside of the female’s body ✓ (1) 2.2.3 Vivipary ✓ (1) 2.2.4 - The baby kangaroo is able to develop within its mother’s pouch for an extended period of time ✓ / till 235 days - This gives greater protection ✓ against environmental threats (accept examples of threats) OR - The baby kangaroo latches onto a teat ✓ of the mother - Providing nutrition ✓ (Mark first ONE only) (Any 1 x 2) (2) 2.2.5 Baby kangaroo is … - blind ✓ - naked ✓ - relies on parent for nutrition ✓ (Any 2 x 1) (2) Copyright reserved Please turn over Hosted by www.ecexams.co.za.

Downloaded from hlayiso.com (EC/SEPTEMBER 2024) LIFE SCIENCES P1 7 2.3 2.3.1 (a) Vitreous humour ✓* / chamber - Contains nutrients for the inner eye ✓ - Maintains eyeball shape ✓ - Transparent to allow for transmission of light to retina ✓ (✓* compulsory + ✓ function) (2) (b) Cornea ✓* - Refraction of light ✓ - Protection ✓ of the eye - Allows light to enter the eye ✓ (✓* compulsory + ✓ function) (2) 2.3.2 - Light entering the eye will not be effectively regulated ✓ /controlled - To much light / to little could enter the eye ✓ - Distorting images that fall on the retina ✓ /causing blurred vision (3) 2.3.3 - Ciliary muscles contract ✓ - Suspensory ligaments slacken ✓ - Tension on the lens decreases ✓ - Lens becomes more convex ✓ / bulged - Refractive power of lens will increase ✓/ light rays are refracted more (a clear image is focused on the retina) (5) 2.4 2.4.1 (a) D ✓ ‒ Oval window ✓ (2) (b) B ✓ ‒ Cochlea ✓ (2) 2.4.2 - Change is speed/ direction of head ✓ - Stimulates the cristae ✓ - Stimulus is converted to an impulses ✓ - Impulse is transmitted to the cerebellum ✓ - Via the auditory nerve ✓ - The cerebellum sends impulses to voluntary / skeletal muscles ✓ to maintain balance (Any 4 x 1) (4) 2.4.3 - Long coiled structure ✓ Increased surface area to detect pressure vibrations of endolymph /✓ enhances the ability to detect low frequency sound OR - Presence of mechanoreceptors / organ of Corti ✓ To convert pressure vibrations into a nerve impulse ✓ OR - Contains fluid ✓/perilymph and endolymph Medium through which pressure vibrations are generated and moves through ✓ (Any 1 x 2) (2) Copyright reserved Please turn over Hosted by www.ecexams.co.za.

Downloaded from hlayiso.com 8 LIFE SCIENCES P2 (EC/SEPTEMBER 2024) 2.5 2.5.1 Geotropism ✓ (1) 2.5.2 Due to rotation of clinostat - Gravity will be even on all sides ✓ / there will be no effect of gravity - Auxins will be evenly distributed ✓ in the root tip - Causing even cell elongation ✓ /growth - Causing the root to grow horizontal ✓ /not to bend (Any 3 x 1) (3) 2.5.3 - Auxin moves to the dark/shaded side ✓ of the stem - High concentration of auxin stimulates growth ✓ - Leading to increased cell growth/elongation ✓ on that side - The stem bends towards the light ✓ (Any 3 x 1) (3) 2.5.4 - Mechanical ✓ /thorns - Chemical ✓ (2) [50] Copyright reserved Please turn over Hosted by www.ecexams.co.za.

Downloaded from hlayiso.com (EC/SEPTEMBER 2024) LIFE SCIENCES P1 9 QUESTION 3 3.1 3.1.1 - 20 rats were placed into each group ✓ To ensure a large sampling size ✓ OR - Testing done 3 time over 90 days ✓ So experiment was repeated ✓ OR - Blood serum samples were harvested at random ✓ In order to obtain an average ✓ (Mark the first ONE) (Any 1 x 2) (2) 3.1.2 - By using rats of the same reproductive ages ✓ - Giving the rats the same amount of water ✓ (Mark the first ONE) (Any 1 x 1) (1) 3.1.3 - Testosterone level ✓ /amount of testosterone (1) 3.1.4 - It is the control / To allow us to compare results ✓ - To show the decrease in testosterone ✓ - Is due to microplastics ✓ - And not the water ✓ (Any 3 x 1) (3) 3.1.5 As microplastics accumulate in an organism’s body (rats), fertility rates will drop ✓✓ OR Fewer microplastics within an organism’s body (rat) will cause a higher fertility rate ✓✓ (2) 3.1.6 - Under the influence of testosterone ✓ - diploid cells in the seminiferous tubules ✓ of the testes - undergo meiosis ✓ - to form haploid sperm cells ✓ (4) 3.1.7 - Low testosterone levels ✓ would result in a - decrease in spermatogenesis ✓/less sperm will be formed/mature (2) 3.2 3.2.1 (a) Adrenal glands ✓ (1) (b) Pancreas ✓ (1) 3.2.2 To maintain level of thyroxin ✓ within narrow limits ✓ in the body (2) 3.2.3 Exocrine - due to its secretion ✓/pancreatic juice - into a duct ✓ Endocrine - secretion of hormone ✓/glucagon/insulin - directly into the blood ✓ (4) Copyright reserved Please turn over Hosted by www.ecexams.co.za.

Downloaded from hlayiso.com 10 LIFE SCIENCES P2 (EC/SEPTEMBER 2024) 3.2.4 - Gland C secretes the hormone adrenalin ✓ - increases conversion of glycogen to glucose ✓ - increase in blood glucose levels ✓ - increase in breathing rate ✓ - more oxygen diffuses into blood stream ✓ - increases heart rate ✓ - dilates blood vessels to skeletal muscles ✓ - more blood reaches skeletal muscles ✓ (Any 5 x 1) (5) 3.2.5 (a) pituitary gland ✓ / hypophysis / Part A (1) (b) Acromegaly ✓ (1) 3.3.1 (a) Ovaries ✓/ graafian follicle /developing follicle (1) (b) Corpus luteum ✓ (1) 3.3.2 - Day 14 ✓ (1) 3.3.3 - LH levels had spiked ✓/peaked (1) 3.3.4 - Implantation/ fertilisation has occurred ✓ - The corpus luteum does not degenerate ✓ /continues to produce progesterone (2) 3.3.5 - High levels of progesterone ✓ - Will inhibit the pituitary gland ✓ - From secreting FSH ✓ - No follicles will be stimulated to develop ✓ (4) 3.4 3.4.1 - Chemoreceptors in the carotid artery are stimulated ✓ by the drop in pH - Impulses are sent to the medulla oblongata ✓ /medulla oblongata is stimulated - The medulla oblongata stimulates the heart ✓ - to beat faster ✓ causing - more carbon dioxide to be taken to the lungs ✓ - the breathing muscles ✓ /intercostal muscles and diaphragm - contract more actively ✓ and - the rate/depth of breathing increases ✓ - more carbon dioxide is exhaled ✓ - The carbon dioxide level in the blood decrease ✓ /returns to normal. (Any 7 x 1) (7) 3.4.2 - The athlete would develop hyperthermia ✓ - Proteins/enzymes may denature ✓ - He/she may lose consciousness ✓ - leading to permanent damage ✓/death (Any 3 x 1) (3) [50] TOTAL SECTION B: 50 GRAND TOTAL: 150 Copyright reserved Please turn over Hosted by www.ecexams.co.za.