Life Sciences Grade 12 Paper 2 NSC June 2021 Memo (English)

Downloaded from hlayiso.com SENIOR CERTIFICATE EXAMINATIONS/ NATIONAL SENIOR CERTIFICATE EXAMINATIONS LIFE SCIENCES P2 2021 MARKING GUIDELINES MARKS: 150 These marking guidelines consist of 13 pages. Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 2 DBE/2021 SC/NSC – Marking Guidelines 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 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/P2 3 DBE/2021 SC/NSC – Marking Guidelines 15. If units are not given in measurements Candidates will lose marks. Marking guidelines 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 learner's 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 memoranda. The provincial internal moderator must be consulted, who in turn will consult with the national internal moderator (and the Umalusi moderators where necessary). 20. Official marking guidelines Only marking guidelines 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/P2 4 DBE/2021 SC/NSC – Marking Guidelines SECTION A QUESTION 1 1.1 1.1.1 C 1.1.2 C/D 1.1.3 A 1.1.4 C 1.1.5 D 1.1.6 D 1.1.7 B (7 x 2) (14) 1.2 1.2.1 Hydrogenbond 1.2.2 Monohybridcross 1.2.3 Stem cells 1.2.4 Centriole/Centrosome 1.2.5 MetaphaseI/II 1.2.6 Haemophilia 1.2.7 Speciation 1.2.8 Punctuated equilibrium 1.2.9 Genetics (9 x 1) (9) 1.3 1.3.1 Both A and B 1.3.2 B only 1.3.3 A only (3 x (6) 2) 1.4 1.4.1 Locus (1) 1.4.2 A - chromatid C - centromere (2) 1.4.3 Crossing over (1) 1.4.4 Prophase I (1) 1.4.5 (a) Ggtt (2) (b) (Plant) height (1) (8) Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 5 DBE/2021 SC/NSC – Marking Guidelines 1.5.1 (a) Y (1) (b) X (1) 1.5.2 4/Four (1) 1.5.3 A; C; T; G (must be in correct order) (1) 1.5.4 - (DNA) replication - Transcription/Protein synthesis (2) (Mark first TWO only) (6) 1.6 1.6.1 (a) 4/Four (1) (b) 1/One (1) 1.6.2 IAi (2) 1.6.3 (a) Son 1 (1) (b) Mother (1) (c) Son 1 (1) (7) TOTAL SECTION A: 50 Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 6 DBE/2021 SC/NSC – Marking Guidelines SECTION B QUESTION 2 2.1 2.1.1 (a) GAC (1) (b) ACU (2) 2.1.2 (Gene) mutation (1) 2.1.3 - CTC on the DNA changed to CAC - Codons (on the mRNA) changed/GAG changed to GUG - Anticodons (on tRNA) changed/CUC replaced by CAC - which resulted in a different amino acid/ Val (4) 2.1.4 - The cells will not receive enough oxygen - resulting in reduced cellular respiration/ a person lacking energy/becoming tired/ anaemia (2) (10) 2.2 - Each tRNA carries an amino acid - When the anticodon on the tRNA - matches the codon on the mRNA - the tRNA brings the (required) amino acid to the ribosome - Amino acids become attached by peptide bonds - to form the (required) protein (6) 2.3 2.3.1 Autosomes (1) 2.3.2 Female (1) 2.3.3 - The gonosomes/chromosome pair 23 - are identical/XX (2) (Mark first ONE only) 2.3.4 The factors/alleles that control a characteristic separate (during meiosis) so that only one is present in each gamete (2) 2.3.5 - A person with Down syndrome will have 3 chromosomes - at position number 21 (2) (8) Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 7 DBE/2021 SC/NSC – Marking Guidelines 2.4 2.4.1 - The grey fur colour is an intermediate phenotype/a blend of black and white - This indicates that neither of the alleles is dominant (2) 2.4.2 P1 Phenotype Grey x Black Genotype BW x BB Meiosis G/gametes B, W x B, B Fertilisation F1 Genotype BB, BB, BW, BW* Phenotype Black Grey* P1 and F1 Meiosis and fertilisation *2 compulsory marks + any 4 OR P1 Phenotype Grey x Black Genotype BW x BB Meiosis Gametes B W Fertilisation B BB BW B BB BW 1 mark for correct gametes 1 mark for correct genotypes* F1 Phenotype Black Grey * P1 and F1 Meiosis and fertilisation *2 compulsory marks + any 4 (6) (8) Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 8 DBE/2021 SC/NSC – Marking Guidelines 2.5 2.5.1 - The dominant allele is always expressed (in the phenotype) when in the heterozygous condition OR - The dominant allele masks/hides the (phenotype of the) recessive allele (2) 2.5.2 (a) N (1) (b) Tt (1) 2.5.3 - J is a taster and therefore must have one dominant allele/T - Individual K is tt - Individual O is a non-taster/is homozygous recessive/tt - She must have inherited a recessive allele/t from each parent - Therefore, J must have one recessive allele/t OR - J is a taster and therefore must have one dominant allele/T - If J is homozygous dominant/TT - and K is homozygous recessive/tt - then it is not possible to have child (O) who is homozygous recessive/ tt - as she must have inherited a recessive allele/t from each parent Any (4) (8) [40] Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 9 DBE/2021 SC/NSC – Marking Guidelines QUESTION 3 3.1 3.1.1 - Bare fingertips/nails instead of claws - Opposable thumbs/ gripping ability - Fingerprints - Five fingers Any (1) (Mark first ONE only) 3.1.2 Differences between African apes and humans African apes Humans - Small cranium - Large cranium - Brow ridges are well - Brow ridges are not well developed developed - Large canines - Small canines - Palate is long and - Palate is small and semi- rectangular / U-shaped circular/ C-shaped - Large jaws - Small jaws - More protruding jaws/ - Less protruding jaws/non- prognathous prognathous - Cranial ridges present - No cranial ridge - Foramen magnum in a - Foramen magnum in a backward position forward position - Sloping face - Flat face - Less developed zygomatic - More developed zygomatic arch arch - Less developed chin - More developed chin - Diastema between the - No diastema between the teeth teeth (Mark first THREE only) Table 1 + (3 x 2) (7) 3.1.3 - Short and - wide/broad - Cup-shaped Any (2) (Mark first TWO only) (10) Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 10 DBE/2021 SC/NSC – Marking Guidelines 3.2 3.2.1 The number of cows producing milk with different fat content 100 93 90 80 Number of cows 70 66 61 60 50 40 30 20 15 11 10 0 2,6 - 3 3,1 - 3,5 3,6 - 4 4,1 - 4,5 4,6 - 5 Fat content (%) (6) Guideline for assessing the graph CRITERIA ELABORATION MARK Correct type of graph (T) Histogram drawn 1 Caption of graph (C) Both variables included 1 Axes labels (L) X- and Y-axis correctly 1 labelled with units Scale for X- and Y-axis (S) - Same width of bars for X-axis and 1 - Correct scale for Y-axis Plotting of bars (P) 1 to 4 bars plotted correctly 1 All 5 bars plotted correctly 2 3.2.2  x 100 = 4,47% (Accept 4,5) (3) 3.2.3 Continuous variation (1) 3.2.4 There is a range of intermediate phenotypes/the fat content % is a range (1) (11) Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 11 DBE/2021 SC/NSC – Marking Guidelines 3.3 3.3.1 Phylogenetic tree/cladogram (1) 3.3.2 Emu and Cassowary (2) (Mark first TWO only) 3.3.3 - A flightless common ancestor - existed on one continent - Due to continental drift the original population split - and each population evolved independently - as they experienced different environmental conditions - Each continent now has a different species of flightless bird Any (4) 3.3.4 - Allow time for them to interbreed/try to interbreed - If they produce infertile offspring/cannot interbreed, they are different species OR - Conduct DNA analysis and - check for differences (2) (9) 3.4 3.4.1 Survival of the owls (1) 3.4.2 The brown owls are less suited to survive than the white owls OR The white owls are more suited to survive than the brown owls (2) 3.4.3 - There is a decrease in the number of white owls because - there is less snow and - white owls will not be camouflaged/will be more visible to predators (3) 3.4.4 - They counted/sampled the number of owls at the beginning of the 4-month period - and again, at the end - Then they calculated the differencebetween the two numbers (3) 3.4.5 (Same): - Time period/4 months - Population - Season/winter - Method of calculation Any (1) (Mark first ONE only) (10) [40] TOTAL SECTION B: 80 Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 12 DBE/2021 SC/NSC – Marking Guidelines SECTION C QUESTION 4 Lamarck (J) - He would use his law of use and disuse - and law of inheritance of acquired characteristics - The ancestor of spider monkeys had short tails - The ancestors continually stretched/used their tails - to be able to hold on to tree branches - As a result, their tails became longer - and this characteristic was passed on to the next generation Any (6) Darwin (D) - Evolution occurs by natural selection - There was variation in the ancestral population - Some spider monkeys had short tails - and some had long tails - Those with short tails could not hold onto tree branches/fell on the ground - They died/were attacked by predators - The spider monkeys with long tails were able to hold on to tree branches/did not fall to the ground - and survived /were not attacked by predators - and reproduced - The characteristic for long tails was passed to the offspring Any (8) Artificial selection (A) - Humans select the spider monkeys with - the long tails - and mate them to produce offspring with long tails - This is repeated over many generations Any (3) Content: (17) Synthesis: (3) (20) Copyright reserved Please turn over

Downloaded from hlayiso.com Life Sciences/P2 13 DBE/2021 SC/NSC – Marking Guidelines ASSESSING THE PRESENTATION OF THE ESSAY Criterion Relevance (R) Logical sequence (L) Comprehensive (C) Generally All information provided is Ideas are arranged in a All aspects required by the relevant to the question logical/cause-effect essay have been sufficiently sequence addressed In this Only information relevant The description of the At least the following are essay in to describing the evolution evolution of long tails in provided when describing the Q4 of long tails in spider spider monkeys for each evolution of long tails in spider monkeys in terms of: of: monkeys: - Lamarck - Lamarck - Lamarck (J: 4/6) - Darwin - Darwin - Darwin (D: 5/8) - Artificial selection - Artificial selection - Artificial selection (A: 2/3) is included. is logical and sequential. There is no irrelevant information. Mark 1 1 1 TOTAL SECTION C: 20 GRAND TOTAL: 150 Copyright reserved