LIFE SCIENCES PAPER 2
GRAD 12
NATIONAL SENIOR CERTIFICATE EXAMINATIONS
MEMORANDUM
MAY/JUNE2021 

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.
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.

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 2)
(6)
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

1. Ggtt✓✓(2)
2. (Plant) height✓ (1)

(8)
1.5.1

1. Y✓(1)
2. X✓ (1)

1.5.2
1.5.3
1.5.4 4✓/Four(1)
A; C; T; G✓ (must be in correct order)

• (DNA) replication✓
• Transcription✓/Protein synthesis
  (Mark first TWO only) (2) (6)

1.6
1.6.1

1. 4✓/Four(1)
2. 1✓/One (1)

1.6.2 IAi✓✓ (2)
1.6.3

1. Son 1✓(1)
2. Mother✓(1)
3. Son 1✓ (1)

(7)
TOTAL SECTION A: 50

SECTION B
QUESTION 2
2.1
2.1.1

1. GAC✓(1)
2. 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
  (Mark first ONE only)(2)

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)

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

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

1. N✓(1)
2. 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]

QUESTION 3
3.1
3.1.1

• Bare fingertips✓/nails instead of claws
• Opposable thumbs✓/ gripping ability
• Fingerprints✓
• Five fingers✓ Any
  (Mark first ONE only) (1)

3.1.2

(Mark first THREE only) Table 1 + (3 x 2)
(7)
3.1.3

• Short✓ and
• wide✓/broad
• Cup-shaped✓ Any
  (Mark first TWO only) (2)

(10)
3.2
3.2.1
(6)
Guideline for assessing the graph

3.2.2
¹¹/₂₄₆ 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)
3.3
3.3.1 Phylogenetic tree✓/cladogram (1)
3.3.2 Emu✓ and Cassowary✓
(Mark first TWO only) (2)
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
  (Mark first ONE only)
  (10)

[40]
TOTAL SECTION B: 80

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

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

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

Content:(17)
Synthesis:(3)
(20)

ASSESSING THE PRESENTATION OF THE ESSAY

TOTAL SECTION C: 20
GRAND TOTAL: 150