Life Sciences Grade 12 Paper 1 GP Prelim 2023 Memo (English)

Downloaded from hlayiso.com PREPARATORY EXAMINATION 2023 MARKING GUIDELINES LIFE SCIENCES (PAPER 1) (10831) 12 pages

Downloaded from hlayiso.com 10831/23 PRINCIPLES RELATING TO THE MARKING OF LIFE SCIENCES 1. If more information than marks allocated is given Stop marking when maximum number of marks is reached and place a wavy line and 'max' in the right-hand margin. 2. If, for example, three reasons are required and five are given Mark only the first three irrespective of whether all or some are correct/incorrect. 3. If whole process is given when only part of it is required Read all and credit relevant part. 4. If comparisons are asked for and descriptions are given Accept if 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 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, provided it does not mean something else in Life Sciences or if it is out of context. 13. If common names given in terminology Accept provided it was accepted at the memo discussion meeting. 2

Downloaded from hlayiso.com 10831/23 14. If only letter is asked for and only name is given (and vice versa) No credit. 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 appears 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. 19. Changes to the marking guidelines No changes must be made to the marking guidelines without consulting the provincial internal moderator. 3

Downloaded from hlayiso.com 10831/23 SECTION A QUESTION 1 1.1 1.1.1 B  1.1.2 A  1.1.3 D  1.1.4 A  1.1.5 B  1.1.6 A  1.1.7 D  1.1.8 C  1.1.9 B  1.1.10 A  (10 x 2) (20) 1.2 1.2.1 Vulva 1.2.2 Adrenal  gland 1.2.3 Homeostasis  1.2.4 Cataract  1.2.5 Copulation  1.2.6 Fallopian tubes  1.2.7 Carbon dioxide  1.2.8 Goitre  1.2.9 Morula  (9 x 1) (9) 4

Downloaded from hlayiso.com 10831/23 1.3 1.3.1 None  1.3.2 A only  1.3.3 Both A and B  (3 x 2) (6) 1.4 1.4.1 (a) A  – Placenta  (Mark first ONE only) (2) (b) C  – Vagina  D  – Cervix  (Mark first ONE only) (2) (c) B  – Amniotic fluid  (Mark first ONE only) (2) (6) 1.5 1.5.1 Reflex arc  (1) 1.5.2 (a) A  (1) (b) E  (1) (c) B  (1) 1.5.3 C, D, F  (accept any order) (1) 1.5.4 Dendrite  (1) 1.5.5 Vertebrae  Meninges  Cerebrospinal fluid  (Mark first TWO only) Any (2) 1.5.6 Myelin sheath  (1) (9) TOTAL SECTION A: [50] 5

Downloaded from hlayiso.com 10831/23 SECTION B QUESTION 2 2.1 2.1.1 Impairment of mental/physical performance/May pose a serious risk to health (1) 2.1.2 0,4 – 0,49 L.h-1  (1) 2.1.3 – The hypothalamus/osmoreceptors is/are stimulated  – and sends impulses to the pituitary gland /hypophysis – to secrete more ADH.  – ADH increases the permeability of the renal tubules – of the kidney. – More water is reabsorbed into surrounding blood vessels.  – The water level in the blood increases to normal  levels. – Less urine is produced /Urine becomes more concentrated /Less water is lost through urine. Any (5) 2.1.4 – Sweating increases  causing the – body temperature to decrease.  – This is because more evaporation of sweat,  causes – more cooling of the skin surface/blood beneath skin surface.  (4) 2.1.5 – Make shifts shorter/at cooler times of the day/morning and night.  – Provide clothing/shade that helps to keep workers cooler. – Supply sufficient (cold) water/fluids for workers.  Any (2) (13) 6

Downloaded from hlayiso.com 10831/23 2.2 2.2.1 (a) A – Liver  B – Pancreas  (2) (b) Insulin  (1) 2.2.2 A regulatory substance in the body that stimulates cells to bring about change. /A protein/chemical messenger in the body. (2) 2.2.3 – Excess glucose cannot be converted to glycogen  – in the liver/organ A – thus, the glucose level in the blood remains above normal /blood glucose levels are high – the person has diabetes. Any (3) 2.2.4 Thyroxin  Adrenalin  Glucagon  (3) (11) 2.3 2.3.1 Phototropism  (1) 2.3.2 Auxins  (1) 2.3.3 A  and B  (2) 2.3.4 – Because the stem is exposed to unilateral light /light from one side only, – auxins/the hormone are/is destroyed by the light /move away from light. – causing the auxins/ hormone concentration to be high on the dark side /side away from the light – therefore, cells are stimulated to elongate/grow on the dark side. /side away from the light. – The auxin/ hormone concentration is low on the side receiving light  – therefore, cells are not stimulated to elongate/ grow on this side. / side facing the light – Therefore, the plant bends/grows towards the light. Any (4) 7

Downloaded from hlayiso.com 10831/23 2.3.5 – As auxins are removed  – plants are kept short /fruit is closer to the ground – fruit is easier to pick /harvest. – Therefore, requires less costly equipment/saves on labour costs. OR – As auxins are removed  – There will be more lateral branches/lateral branches are longer – they can carry more fruit /higher yields. – Therefore, more income from sales.  Any (3) (11) 2.4 2.4.1 Right  side (1) 2.4.2 Decreased pupil size  Drooping eyelid  Decreased sweating  (Mark first ONE only) Any (1) 2.4.3 Cerebrum  (1) 2.4.4 Autonomic  nervous system (1) 2.4.5 As pupil is too small it cannot dilate enough to let more light in  there is a greater risk of having an accident at night , because it will be difficult to see in the dark /dim light. Any (2) 2.4.6 Adrenalin Parasympathetic nervous system increases heart rate decreases heart rate constricts blood vessels in the dilates blood vessels in skin/vasoconstriction skin/vasodilation dilates pupils constricts pupils increases blood pressure decreases blood pressure widens bronchioles narrows bronchioles decreases peristalsis increases peristalsis causes relaxation of the bladder causes contraction of the bladder wall wall stimulates sweat secretion less sweat is secreted (Mark first TWO only) Any (2 x 2) + 1 Table (5) 8

Downloaded from hlayiso.com 10831/23 2.4.7 Accommodation * – Ciliary muscles contract  – Suspensory ligaments slacken  – Tension on the lens decreases  – Lens becomes more convex  – Increasing the refractive power of the lens  – Forming a (clear) image on the retina  Any (3 + 1* compulsory) (4) (15) [50] QUESTION 3 3.1 3.1.1 Deepening of the voice ✓/larynx enlarges Broadening of the chest ✓/shoulders More muscular physique✓ Penis/testes/sex organs enlarge ✓ (Mark first TWO only) Any (2) 3.1.2 To determine the relationship between the density of beard growth and the concentration/level of testosterone. ✓✓ OR To determine the effect of testosterone levels on beard density✓✓ (Must include “to” and both variables) (2) 3.1.3 All males should have the same: – Age ✓ – Diet ✓ – Health ✓/level of activity – Race ✓ – Environment ✓ (Mark first THREE only) Any (3) 3.1.4 0,52 + 0,53 + 0,52 + 0,51 + 0,53 0,261  OR 5 5 = 0,522  µg  (accept 0,52 or 0,5) (3) 3.1.5 Rejected ✓* A greater density of beard growth was not shown to correspond with an increased testosterone level. ✓/Even when density of hair growth was more, testosterone levels remained similar. (1* compulsory + 1) (2) (12) 9

Downloaded from hlayiso.com 10831/23 3.2 3.2.1 C – Primary follicle  (1) 3.2.2 Ovarian ✓ cycle (1) 3.2.3 C; B; A ; E; D  (Mark first FIVE only) (2) 3.2.4 Diagram of an ovum Criteria Elaboration Symbol Mark Drawing Correct representation of an ovum D (1) (single, round cell with a nucleus) Labels ANY correct labels as shown in the L sketch above. • One correct label (1) • Two correct labels (2) Caption Structure identified as an ovum C (1) TOTAL (4) (4) 3.2.5 (a) FSH  and LH  (2) (b) Oestrogen  and progesterone  (2) 3.2.6 – The degeneration of the corpus luteum✓ – leads to a decrease in progesterone.✓ – The endometrium is no longer maintained ✓/shed/menstruation occurs. – Thus, FSH increases ✓ causing the next cycle to start. Any (3) (15) 10

Downloaded from hlayiso.com 10831/23 3.3 3.3.1 (a) Ossicles  (1) (b) Cochlea  (1) 3.3.2 – Sound waves cannot be (effectively) converted to vibrations by the eardrum/tympanic membrane – and the ossicles do not vibrate /vibrate less – therefore, the oval window does not vibrate /vibrates less – no/little pressure waves form in the cochlea – The Organ of Corti picks up little or no stimulus  – and little or no impulse is carried by the auditory nerve  – with little or no interpretation occurring in the cerebrum Any (4) 3.3.3 The person can hear 15 dB /normal dB range/0-25 dB range (1) 3.3.4 Minimum audible sound intensity over a 12 month period Minimum audible sound intensity (dB) 90 78 80 70 60 50 41 40 30 30 20 15 10 0 3 6 9 12 Time (Months) CRITERIA: Guidelines for assessment of ELABORATION MARK the graph Correct type of graph (T) Bar graph drawn 1 Caption for graph (C) Both variables included 1 Axes labels (L) X- and Y-axis correctly labelled with units 1 Scale for X- and Y-axis (S) Equal space and width of bars on X-axis AND Correct scale for Y-axis 1 Plotting of points (P) 1 to 3 co-ordinates plotted correctly 1 All coordinates plotted correctly 2 (6) (13) 11

Downloaded from hlayiso.com 10831/23 3.4 3.4.1 (a) C (1) (b) A (1) (c) B (1) 3.4.2 The Eustachian tube  allows air to move into and out of the middle ear.  (2) 3.4.3 – Cristae  – in the ampullae/semi-circular canals are stimulated  – by a change in the speed and direction of the body/head – the stimulus is converted into an impulse  – the impulses are sent via the auditory nerve  – to the cerebellum  – the cerebellum then sends impulses to the skeletal muscles  to restore the balance. Any (5) (10) [50] TOTAL SECTION B: 100 TOTAL: 150 12