Life Sciences Grade 12 P1 NSC November 2021 Memo (English)

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE GRADE 12 LIFE SCIENCES P1 NOVEMBER 2021 MARKING GUIDELINES MARKS: 150 These marking guidelines consist of 9 pages. Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P1 2 DBE/November 2021 NSC – 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. Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P1 3 DBE/November 2021 NSC – Marking Guidelines 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. 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/November 2021 NSC – Marking Guidelines SECTION A QUESTION 1 1.1 1.1.1 C 1.1.2 B 1.1.3 D 1.1.4 C 1.1.5 A 1.1.6 B 1.1.7 C 1.1.8 B 1.1.9 A (9 x 2) (18) 1.2 1.2.1 Ovulation 1.2.2 Synapse 1.2.3 Gestation 1.2.4 Tropism 1.2.5 Precocial development 1.2.6 Allantois 1.2.7 Seminiferous tubules 1.2.8 Abscisic acid (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 1.4.1 (a) Vas deferens/sperm duct (1) (b) Scrotum (1) (c) Penis (1) 1.4.2 (a) D Epididymis (2) (b) G Urethra (2) (c) E Testis (2) 1.4.3 A B E Any (2) (Mark first TWO only) (11) 1.5 1.5.1 (a) Cytoplasm (1) (b) Jelly layer (1) (c) Tail/ Flagellum (1) 1.5.2 Mitochondrion (1) 1.5.3 A and F (2) (Mark first TWO only) 1.5.4 Oogenesis (1) (7) TOTAL SECTION A: 50 Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P1 5 DBE/November 2021 NSC – Marking Guidelines SECTION B QUESTION 2 2.1 2.1.1 Motor /efferent neuron (1) 2.1.2 C  B  A (2) (Must be in the correct sequence) 2.1.3 - Impulses will be transmitted faster in neuron 1/ slower in neuron 2 - because of the presence of a myelin sheath in neuron 1/ absence of a myelin sheath in neuron 2 (3) 2.1.4 - Impulses from the receptor/sensory neuron - will be transmitted to the central nervous system but - the impulse will not reach the effector (3) (9) 2.2 2.2.1 Choroid (1) 2.2.2 - Holds the lens in position - Connects the lens to the ciliary body - Plays a role in accommodation Any (1) (Mark first ONE only) 2.2.3 (D/the yellow spot) has the highest concentration of cones (1) 2.2.4 - Part B/sclera is opaque/does not allow light to pass through/ white - part F/lens is transparent/allows light to pass into the eye OR - Part B/sclera is non-elastic/maintains the shape of the eye - part F/lens is elastic/able to change its shape (4) (Mark first ONE only) 2.2.5 - The circular muscles relax - The radial muscles contract - causing the pupil to dilate (3) 2.2.6 - The lenses in the spectacles will refract the light rays - The lens of the eye also refracts the light rays - The light rays will therefore be focused in front of the retina (3) (13) Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P1 6 DBE/November 2021 NSC – Marking Guidelines 2.3 2.3.1 Uterus (1) 2.3.2 - The thickened layer may cause an obstruction/blockage - which may prevent the passage of gametes - preventing fertilisation from taking place OR - The thickened layer may cause an obstruction/blockage - which may prevent the embryo from reaching the uterus/ implantation could occur in the Fallopian tube - which may lead to the death of the embryo/rupturing of the fallopian tube/miscarriage (3) 2.3.3 - A high concentration of progesterone - inhibits the pituitary gland from secreting FSH - Without FSH a follicle will not develop in the ovary - Therefore, oestrogen will not be secreted (4) (8) 2.4 - The pinna of the ear traps sound waves - The auditory canal directs the sound waves to the tympanic membrane - causing the tympanic membrane to vibrate - which causes the ossicles to vibrate and - pass the vibrations to the oval window/amplify the vibrations - (Pressure) waves are set up in the inner ear/perilymph/endolymph - The organ of Corti is stimulated - and converts the stimuli into impulses - which are transmitted by the auditory nerve - to the cerebrum for interpretation Any (7) Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P1 7 DBE/November 2021 NSC – Marking Guidelines 2.5 2.5.1 Chorion (1) 2.5.2 - Acts as a shock absorber - It prevents desiccation/dehydration - It helps to keep the temperature within a narrow range - It facilitates free movement of the foetus Any (2) (Mark first TWO only) 2.5.3 - The zygote divides by mitosis - to form a (solid) ball of cells - called the morula - which develops into a hollow ball of cells - called the blastula/blastocyst Any (4) 2.5.4 - Acts as a micro-filter/protect against pathogens - Removal of harmful metabolic waste - Produces antibodies - Maintains the endometrium Any (2) (Mark first TWO only) 2.5.5 Umbilical vein (1) 2.5.6 - In humans the developing foetus receives nutrients from the mother’s blood - via the placenta/umbilical vein - In oviparous organisms the developing embryo receives nutrients from the yolk/albumen Any (3) (13) [50] Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P1 8 DBE/November 2021 NSC – Marking Guidelines QUESTION 3 3.1 3.1.1 Cerebellum (1) 3.1.2 - Connects the two hemispheres of the brain - Allows for communication between the two hemispheres of the brain Any (1) (Mark first ONE only) 3.1.3 D Cerebrum (2) 3.1.4 (a) Adrenalin (1) (b) - More air/oxygen will be inhaled - Blood will be pumped faster - therefore, transporting more oxygen and glucose to the skeletal muscles - which will increase the rate of cellular respiration/metabolism (4) (c) - Part B/the medulla oblongata is stimulated - and sends impulses to the heartand to - the breathing muscles/ intercostal muscles and diaphragm - More blood is transported to the lungs - and the carbon dioxide is exhaled faster (4) - and the carbon dioxide levels return to normal Any (13) 3.2 3.2.1 50°C (1) 3.2.2 As the temperature increases the average rate of blood-flow to the skin increases (2) 3.2.3  x 100 = 175% OR  x 100 = 175% (3) 3.2.4 - As the temperature increases from 20 °C to 45 °C - vasodilation occurs/blood vessels dilate - to increase the rate of blood flow /more blood flows to the skin - so that more heat/ sweat can be lost (4) 3.2.5 - Less blood flows to the skin at low temperatures - Less oxygen/nutrients reach the cells of the tissue and the cells may die OR - Less blood flows to the skin at low temperatures - More carbon dioxide/waste products accumulate in the cells of the tissue and the cells may die (2) (12) Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P1 9 DBE/November 2021 NSC – Marking Guidelines 3.3 3.3.1 - The pituitary gland is stimulated - to secrete less TSH - Low TSH levels causes the thyroid gland - to secrete less thyroxin - Thyroxin levels return to normal (5) 3.3.2 - The rate of metabolism/respiration in the body decreases - Less glucose will be broken down - and more glucose will be converted and stored as (3) fat/glycogen (8) 3.4 3.4.1 Stem growth (1) 3.4.2 - To remove the source of auxins - The tip produces auxins Any (1) 3.4.3 To increase the reliability/validity of the results (1) 3.4.4 B and C (2) 3.4.5 - The presence of auxins in the tip of the stem - stimulate upward growth - and inhibit development of lateral branches (3) 3.4.6 (a) Gibberellins (1) (b) Abscisic acid (1) (10) 3.5 3.5.1 Internal fertilisation (1) 3.5.2 - Internal fertilisation increases the chances of fertilisation - Ovovivipary/ eggs retained inside the female’s body where they are protected (Mark first TWO only) (2 x 2) (4) 3.5.3 - To increase the chances of fertilisation/ the survival of the eggs/ number of offspring - As eggs may be lost to predators/environmental factors etc - Since there is external fertilisation Any (2) (7) [50] TOTAL SECTION B: 100 GRAND TOTAL: 150 Copyright reserved