Life Sciences Grade 12 Paper 1 NSC June 2017 Memo (English)

Downloaded from hlayiso.com SENIOR CERTIFICATE EXAMINATIONS LIFE SCIENCES P1 2017 MARKING GUIDELINES MARKS: 150 These marking guidelines consist of 10 pages. Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P1 2 DBE/2017 SCE – Marking Guidelines 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. 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. Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P1 3 DBE/2017 SCE – 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 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 memorandum No changes must be made to the memoranda without consulting the provincial internal moderator who in turn will consult with the national internal moderator (and the Umalusi moderators where necessary). 20. Official memoranda Only memoranda bearing the signatures of the national internal moderator and the Umalusi moderators and distributed by the National Department of Basic Education via the provinces must be used. Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P1 4 DBE/2017 SCE – Marking Guidelines SECTION A QUESTION 1 1.1 1.1.1 C 1.1.2 D 1.1.3 B 1.1.4 D 1.1.5 C 1.1.6 B 1.1.7 A 1.1.8 B 1.1.9 B 1.1.10 D (10 x 2) (20) 1.2 1.2.1 Biodiversity 1.2.2 Carbon footprint 1.2.3 Thermalpollution 1.2.4 Eutrophication 1.2.5 Testosterone 1.2.6 Vas deferens/sperm duct 1.2.7 Aldosterone 1.2.8 Prolactin 1.2.9 Cytokinesis (9 x 1) (9) 1.3 1.3.1 A only (2) 1.3.2 B only (2) 1.3.3 Both A and B (2) (3 x 2) (6) 1.4 1.4.1 (a) D Synapse (2) (b) C Interneuron/Connector neuron (2) (c) A Dendrite (2) 1.4.2 (a) E (1) (b) F (1) (8) 1.5 1.5.1 (a) Zygote (1) (b) Morula (1) (c) Placenta (1) 1.5.2 (a) Fertilisation (1) (b) Implantation (1) 1.5.3 (a) 46/23 pairs (1) (b) 23 (1) (7) TOTAL SECTION A: 50 Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P1 5 DBE/2017 SCE – Marking Guidelines SECTION B QUESTION 2 2.1 2.1.1 - The hatchling's eyes are closed - The hatchling can't move - The hatchling can't feed on its own - The hatchling has no feathers/wings are not developed (Any 2) (2) (MARK FIRST TWO ONLY) 2.1.2 - Foetus develops inside the uterus for greater protection - Food is supplied by the mother and is therefore supplied for a longer period (Any 1 x 2) (2) (MARK FIRST ONE ONLY) 2.1.3 - More yolk allows for greater development of the chick - so that it can be more independent after hatching (2) (6) 2.2 2.2.1 Macular degeneration/Retina cells die (1) 2.2.2 14.1/142 x 100 = 9.93% (Accept 9.9 and 10%) (3) 2.2.3 L The number of people suffering from cataracts, short- sightedness and long sightedness 40 Number of people (millions) 34.1 T 35 P 30 24.4 25 20 14.1 15 10 5 0 Cataract CataractShort-sightedness Short-sightedLong-sightedness Long-sighted S Eye disorder/disease Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P1 6 DBE/2017 SCE – Marking Guidelines Mark allocation of the graph Criteria Mark allocation Bar graph drawn for 3 relevant diseases (T) 1 Title of graph 1 Correct scale for X-axis (equal width and 1 spacing of the bars) and Y-axis (S) Correct label and unit for X-axis and Y-axis 1 (L) Plotting of the bars (P) 0: No bars plotted correctly 1: 1 to 2 bars plotted correctly 2: All 3 bars plotted correctly NOTE: If a line graph is drawn – marks will be lost for the ‘type and scale' If a histogram is drawn – marks will be lost for the 'type of graph and correct scale' (6) 2.2.4 (a) Cataract (1) (b) Short-sightedness (1) (12) 2.3 2.3.1 (a) Crop yields are dropping (1) (b) Water supplies are decreasing (1) 2.3.2 395 parts per million/ppm (Accept 394 – 396 ppm) (2) 2.3.3 - Decreased photosynthesis - Less CO 2 used from the atmosphere - therefore more carbon dioxide accumulates in the atmosphere - This leads to the enhanced greenhouse effect causing more global warming (Any 3) OR - Burning of forests - releasing CO 2  - leading to the enhanced greenhouse effect causing more global warming (3) (7) 2.4 - An excessive growth of water hyacinths on the surface of the water will block out the light/deprive submerged plants of sunlight - this limits photosynthesis/disrupts food chains/food webs - Alien plants outcompete the indigenous species/Alien plants have no natural enemies - this may lead to some of the indigenous species becoming eliminated/ disruption of the food chain/web - The great demand of alien plants on natural resources, - results in less resources being available for the indigenous species (3 x 2) (6) (MARK FIRST THREE ONLY) Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P1 7 DBE/2017 SCE – Marking Guidelines 2.5 2.5.1 Centriole (1) 2.5.2 Metaphase II (1) 2.5.3 - Single chromosomes - arranged at the equator of the cell (2) 2.5.4 - There is a random arrangement of chromosomes at the equator/the chromosomes flip over - Causing the chromosomes in the gametes to be different/Chromatids move in different combinations into each gamete (2) 2.5.5 (a) 6 (1) (b) 3 (1) 2.5.6 Crossing over (1) (9) [40] Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P1 8 DBE/2017 SCE – Marking Guidelines QUESTION 3 3.1 3.1.1 Does drinking coffee containing caffeine increase stamina?  (2) 3.1.2 (a) Amount of caffeine/Presence or absence of caffeine (1) (b) - Stamina - By measuring the average duration of cycling (2) 3.1.3 The average cycling time of the cyclists/stamina increased with the use of caffeine (2) 3.1.4 - Decaffeinated coffee serves as a control - to eliminate any other factor that may cause an increase in stamina/to confirm that caffeine causes the change (2) 3.1.5 - Knowing whether caffeine is taken or not - may subconsciously influence the performance of the participants. OR - The participants may think they have more stamina if they know that they are taking caffeine and - this may influence their performance (2) 3.1.6 - If too little time passes between the exercise tests, the participants may be tired - which will influence their stamina for the second cycle test and therefore the validity of the investigation OR - The participants must be equally rested for both tests - to ensure the validity of the investigation OR - The cyclist may perform better in the second test because they are better warmed up if the time between the tests is too short. - This may influence the validity of the investigation ( Any 1 x 2) (2) (13) 3.2 3.2.1 (a) Oestrogen (1) (b) Progesterone (1) 3.2.2 - It increases - the thickness of the endometrium/the blood vessels in the endometrium/the amount of glandular tissue in the endometrium (2) 3.2.3 (a) Release of an ovum from the ovary/Graafian follicle (2) (b) Day 14 (1) (c) LH/Luteinizing hormone (1) Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P1 9 DBE/2017 SCE – Marking Guidelines 3.2.4 - High levels of hormone B/progesterone will inhibit - the secretion of FSH OR - No new ova/mature follicles - are required during pregnancy (2) 3.2.5 - The progesterone - levels decreased - because the corpus luteum degenerated (3) (13) 3.3 3.3.1 Geotropism/gravitropism (1) 3.3.2 - Auxins - accumulate at the lower part of the stem - because of gravity - The higher concentration of auxins at the lower part of the stem stimulates cell elongation/growth on the lower side of the stem - The lower concentration of auxins at the upper part of the stem inhibits cell elongation/growth on the upper side of the stem (Any 4) (4) 3.3.3 - The leaves and stem will be carried in such a way that they receive maximum sunlight - for photosynthesis OR - Exposes the flowers more favourably - for pollination/seed dispersal (2) 3.3.4 The roots will grow downwards/towards gravity (1) (8) 3.4 3.4.1 Hypothalamus (1) 3.4.2 - As the level of ADH in the blood increases the tubular reabsorption of water increases OR - As the level of ADH in the blood decreases the tubular reabsorption of water decreases (2) 3.4.3 - On a cold day the body loses less water through sweating/ the blood has more water than normal - The hypothalamus sends impulses to the - pituitary gland - to secrete less ADH (Any 3) (3) (6) [40] TOTAL SECTION B: 80 Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P1 10 DBE/2017 SCE – Marking Guidelines SECTION C QUESTION 4 Thermoregulation - Receptors in the skin detect the stimulus - Send the impulses to the hypothalamus of the brain - The hypothalamus sends impulses to the blood vessels of the skin - Blood vessels constrict (become narrow)/vasoconstriction occurs - Less blood flows to the skin - Less heat is lost from the skin - Less blood is sent to the sweat glands - Sweat glands become less active/Less sweat is released - There is less evaporation of sweat - and less cooling of the skin Max (8) Hearing - The pinna traps the sound waves - and directs them into the auditory canal/meatus - This causes the tympanic membrane to vibrate - The vibration is transmitted to the auditory ossicles/(malleus, incus, stapes) - The ossicles amplify the vibration - and transmit it to the oval window - The oval window vibrates - creating pressure waves - in the endolymph - which stimulates the Organ of Corti - The stimulus is converted to an impulse - The impulse is transmitted via the auditory nerve - to the cerebrum - where sound is interpreted Max (9) Content: (17) Synthesis: (3) (20) ASSESSING THE PRESENTATION OF THE ESSAY Relevance Logical sequence Comprehensive All information provided is relevant to Ideas arranged in a logical/ Answered all aspects required the question cause-effect sequence by the essay in sufficient detail Only information regarding: The sequence of events in At least the following points - Thermoregulation in cold thermoregulation and hearing is should be included: conditions and in the correct order. - Thermoregulation in cold - Hearing is described conditions (5/8) No irrelevant information. - Hearing (6/9) 1 mark 1 mark 1 mark TOTAL SECTION C: 20 GRAND TOTAL: 150 Copyright reserved