# Life Sciences Grade 12 Paper 2 NSC June 2017 Memo (English)

> Grade 12 Life Sciences Paper 2 memorandum from the NSC June Exam 2017 (English), 11 pages. Read online or download the free PDF.

- Page: https://www.hlayiso.com/library/life-sciences-p2-may-june-2017-memo-eng/ac055537-b682-4f91-8ae5-b842212979ad
- Updated: 2026-09-27
- Subject: Life Sciences
- Grade: Grade 12
- Document type: Memorandum
- Year: 2017
- Exam period: NSC June Exam
- Paper: 2
- Curriculum: CAPS
- Pages: 11

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Life Sciences · Grade 12 · NSC June Exam · 2017. Memorandum, 11 pages. Read online or download the PDF.

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                     SENIOR CERTIFICATE EXAMINATIONS

                                  LIFE SCIENCES P2

                                           2017

                                MARKING GUIDELINES

                                                                       MARKS: 150

                      These marking guidelines consist of 11 pages.

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Life Sciences/P2                              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.

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Life Sciences/P2                             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 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 memorandum
    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 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.

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Life Sciences/P2                                 4                                DBE/2017
                                       SCE – Marking guidelines

SECTION A
QUESTION 1
1.1       1.1.1       A
          1.1.2       B
          1.1.3       A
          1.1.4       C
          1.1.5       C
          1.1.6       NO CORRECT ANSWER
          1.1.7       D
          1.1.8       C
          1.1.9       D
          1.1.10      C                                                       ( 9 x 2)      (18)
1.2       1.2.1       Locus
          1.2.2       Australopithecus
          1.2.3       Pedigree diagram
          1.2.4       Peptide bond
          1.2.5       Interphase
          1.2.6       (Homo) habilis
          1.2.7       Stem/ meristematic cells
          1.2.8       Artificial selection/selective breeding                  (8 x 1)       (8)
1.3       1.3.1       Both A and B
          1.3.2       Both A and B
          1.3.3       None                                                     (3 x 2)      (6)
1.4       1.4.1       B- Cranium 
                      C- Brow ridge                                                          (2)

          1.4.2       Canine                                                                 (1)

          1.4.3       (a) I ; II                                (Mark first TWO only)       (2)
                      (b) II                                     (Mark first ONE only)       (1)
                      (c) III                                     (Mark first ONE only)      (1)
                      (d) III                                    (Mark first ONE only)       (1)

          1.4.4       C                                                                      (1)

          1.4.5       III  I  II                                                          (2)
                                                                                              (11)

1.5       1.5.1       100%                                                                   (1)

          1.5.2       Non-haemophiliac female /Normal female                                 (1)

          1.5.3       (a) XhY                                                                (1)
                      (b) XH Xh                                                             (2)
                                                                                              (5)

                                                                     TOTAL SECTION A: 50

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Life Sciences/P2                              5                                   DBE/2017
                                    SCE – Marking guidelines

QUESTION 2

2.1       2.1.1       mRNA/messenger RNA                                                      (1)

          2.1.2       (a) Nitrogenous base                                                    (1)
                      (b) Ribose                                                              (1)

          2.1.3       - The double stranded DNA molecule unwinds
                      - and unzips/separates
                      - when the hydrogen bonds break 
                      - One strand is used as a template
                      - to form mRNA
                      - using free RNA nucleotides from the nucleoplasm
                      - The mRNA is complementary to the DNA/A-U, C-G
                      - This process is controlled by enzymes                   Any 5         (5)
                                                                                               (8)

2.2       2.2.1       - Crossing over
                      - Random arrangement of chromosomes/                   OR
                        Independent/random assortment of chromosomes          meiosis
                      - Random fertilisation
                      - Random mating                                            Any 3        (3)
                      (Mark first THREE only)

          2.2.2       - Continuous variation occurs when there is a range of phenotypes
                        for the same characteristic/has intermediate forms,
                      - whereas discontinuous variation occurs when phenotypes fit into
                        separate or distinct categories/with no intermediate forms            (2)
                                                                                               (5)

2.3       2.3.1       (a) GGT                                                                 (1)
                      (b) AAA                                                                 (1)
                      (c) UCA                                                                 (1)

          2.3.2       (a) 1                                                                   (1)
                      (b) 198                                                                 (1)
                      (c) 66                                                                  (1)

          2.3.3       - One of the base triplets on the DNA has changed
                      - from ACG to ACC
                      - The triplet ACG codes for the amino acid cysteine
                      - while the triplet ACC codes for the amino acid tryptophan
                      - resulting in a change in the sequence of amino acids      Any 4       (4)
                                                                                               (10)

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Life Sciences/P2                               6                                    DBE/2017
                                     SCE – Marking guidelines

2.4       2.4.1       (a)   Temperature                                                        (1)
                      (b)   Number of clover plants that survived/percentage survival          (1)

          2.4.2       - Repeat the investigation
                      - Set up more greenhouses at each temperature
                      - Use a larger sample of clover plants
                      - Increase the period of the investigation                   Any 2       (2)
                      (Mark first TWO only)

          2.4.3       They counted the number of clover plants that survived and divided
                      it by the original number/200
                      then multiplied it by 100                                                (2)

          2.4.4       - The hypothesis will be accepted
                      - because there are more clover plants/higher percentage
                        survival
                      - at the higher temperature
                                               OR
                      - The hypothesis will be accepted
                      - because there are fewer clover plants/ lower percentage
                        survival
                      - at the lower temperature                                               (3)

          2.4.5       - The bitter tasteof the cyanide in the clover plants
                      - prevents herbivores/predators from feeding on them                     (2)

          2.4.6       - The mutation caused variation amongst the clover plants
                      - Some produce cyanide and
                      - others do not produce cyanide
                      - The cyanide-producing plants are killed at lower temperatures
                      - The non-cyanide-producing plants survive at the lower
                         temperatures and reproduce
                      - The allele for cyanide production is not passed on to the next
                        generation
                      - decreasing the number of cyanide producing clover plants in
                        the next generation                                         Any 6       (6)
                                                                                                (17)
                                                                                                [40]

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Life Sciences/P2                                  7                                  DBE/2017
                                        SCE – Marking guidelines

QUESTION 3
3.1       3.1.1        - A pair of chromosomes that are similar in length
                       - Carry genes for the same characteristics
                       - Have alleles at the same loci
                       - Have the same centromere position
                       - One is obtained from each parent                          Any 2         (2)
                       (Mark first TWO only)

          3.1.2        Spindle fibre                                                             (1)

          3.1.3        (a) 8                                                                     (1)
                       (b) 4                                                                     (1)

          3.1.4
                     chromatid                                                cell membrane

                                                                               nuclear membrane

                                                                              centrosome
          nucleoplasm
                                                                              chromosome

                                                                             cytoplasm

                                                                      centromere

                                                Telophase I

         Criteria to mark diagram
          Single cell is drawn                           (S)           1
          Only 2 replicated chromosomes in drawing        (T)          1
          One replicated chromosome longer than the other (L)          1
          Caption                                                      1
          Any TWO correct labels                                       2
                                                                                                  (6)
          3.1.5        (a)   RrTt                                                                (1)

                       (b)   RT, rt                                                             (2)
                                                                                                  (14)

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Life Sciences/P2                                 8                                                        DBE/2017
                                       SCE – Marking guidelines

3.2
                     P1              Phenotype       Blood type A            x            Blood type B*
                                     Genotype                  IAi           x            IBi*
                     Meiosis
                                     G/gametes              IA, i            x            IB, i 
                     Fertilisation
                     F1              Genotype              IAIB;     IA i;          IBi       ii

                                     Phenotype           Blood type AB                    Blood type O 

                     P 1 and F 1 
                     Meiosis and fertilisation

                                                         OR

                     P1              Phenotype       Blood type A            x            Blood type B*
                                     Genotype                  IAi           x            IBi*

                     Meiosis
                                                    Gametes                   IA                     i
                     Fertilisation                     IB                    A B
                                                                             I I                    I i
                                                                                                     B

                                                        i                    IA i                    ii

                                                      1 mark for correct gametes
                                                      1 mark for correct genotypes

                     F1              Phenotype      Blood type AB and Blood type O 

                     P 1 and
                     F1                                                                                             (6)
                     Meiosis and fertilisation
                                                                     *compulsory 2 + any 4

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Life Sciences/P2                               9                                      DBE/2017
                                     SCE – Marking guidelines

3.3       3.3.1       DNA profiling (DNA fingerprinting)                                         (1)

          3.3.2       Male 3                                                                     (1)

          3.3.3       - The bands of the child’s DNA is a combination of the DNA from
                        each parent 
                      - Three bands are identical to that of the mother
                      - The remaining (three) bands correspond with that of male 3               (3)

          3.3.4       - To investigate crimes/resolve disputes
                      - To identify organisms from their remains
                      - To identify missing persons
                      - To identify family relationships other than paternity e.g. siblings
                         or cousins
                      - To test for the presence of specific alleles/genes that cause a
                        genetic disorder
                      - To establish matching tissues for organ transplants          Any 2       (2)
                      (Mark first TWO only)                                                       (7)

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Life Sciences/P2                              10                                  DBE/2017
                                    SCE – Marking guidelines

3.4       3.4.1       Genetic engineering/modification/manipulation/recombinant DNA
                      technology                                                               (1)

          3.4.2       - Can kill other useful insects
                      - Can cause pollution
                      - May cause harm to consumers of the produce
                      - Development of insecticide-resistant organisms         Any 1          (1)
                      (Mark first ONE only)

          3.4.3       - Use the same field/greenhouse
                      - Use the same number of plants
                      - Use the same species of wheat
                      - Measure the crop yield over the same period
                      - Use same techniques of measuring the crop yield        Any 2          (2)
                      (Mark first TWO only)

          3.4.4       50                                                                      (1)

          3.4.5       Difference in yield: (70 – 45) = 25                                    (2)

          3.4.6       - In the greenhouses high yield
                      - In the fields low yield                                               (2)

          3.4.7       - The conditions in the greenhouse can be controlled 
                      - whereas there are many variations in the conditions for wheat
                        grown in fields
                                                    OR
                      The environmental conditions/ (examples) in the greenhouse
                      may have differedfrom that in the field                                 (2)

          3.4.8       - Expensive/research money could be used for other needs
                      - Potential health impacts
                      - Interfering with nature
                      - Not sure of long-term effects
                      - Did not increase the yield                        Any 2               (2)
                      (Mark first TWO only)
                                                                                               (13)
                                                                                               [40]

                                                                          TOTAL SECTION B: 80

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Life Sciences/P2                               11                                     DBE/2017
                                     SCE – Marking guidelines

SECTION C
QUESTION 4
Differences
- A species is a group of organisms with similar characteristics D
- that are able to interbreed D
- to produce fertile offspring D
- A population is a group of organisms of the same species D
- found in the same habitat D
- at the same time D

Speciation by geographic isolation
- A population of organisms becomes split S
- by a geographical barrier S/example of a geographical barrier.
- The two populations cannot interbreed S/there is no gene flow between the two.
- Natural selection occurs independently S in each population.
- Due to different environmental conditions S on either side of the barrier,
- the two populations become genotypically and phenotypicallyS
- different S from each other.
- Even if the geographical barrier is removed, the individuals will not be able to
  interbreed S
- We say that the original population has now become two separate speciesS

Effect of speciation and extinction on biodiversity
- Since there is an increase in the number of species B
- speciation increases B biodiversity
- Extinction results in the loss of the number of species B
- therefore results in a decrease B in biodiversity                                Any 17
                                                                                   Content:        (17)
                                                                                  Synthesis:        (3)
                                                                                                  (20)
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 sequence essay         have       been
                                                                       sufficiently addressed
In this      Only information relevant   All the information regarding At least:
essay in     to the differences between the differences between        - 4 correct points for the
Q4           population and species;     population and species, the   differences,
             the description of          description of speciation and - 5 for the description of
             speciation and effect of    the effect of speciation and  speciation and
             speciation and extinction   extinction on biodiversity is - 2 for effects of speciation
             on biodiversity is given    given in a logical manner     and extinction on
                                                                       biodiversity
Mark                       1                             1                            1

                                                                          TOTAL SECTION C: 20
                                                                             GRAND TOTAL: 150

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