LIFE SCIENCES
PAPER 2
GRADE 12 
NSC PAST PAPERS AND MEMOS
FEBRUARY/MARCH 2018

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.
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.

MEMORANDUM 

SECTION A
QUESTION 1 
1.1
1.1.1 A✔✔
1.1.2 B✔✔
1.1.3 C✔✔
1.1.4 B✔✔
1.1.5 A✔✔
1.1.6 C✔✔
1.1.7 C✔✔
1.1.8 C✔✔
1.1.9 A✔✔ ( 9 x 2) (18) 
1.2
1.2.1 tRNA✔/transfer RNA  
1.2.2 Cloning✔
1.2.3 Stem✔cells 
1.2.4 Incomplete dominance✔
1.2.5 Artificial selection✔/selective breeding 
1.2.6 Chiasma✔
1.2.7 Ribosome✔
1.2.8 Biodiversity✔ (8 x 1) (8) 
1.3
1.3.1 B only✔✔
1.3.2 Both A and B✔✔
1.3.3 A only✔✔ (3 x 2) (6) 
1.4
1.4.1 DNA✔/Deoxyribonucleic acid (1)
1.4.2

• Nucleus✔/chromosome
• Mitochondria✔
  (Mark first TWO only) (2) 

1.4.3

1. Nucleotide✔ (1) 
2. Guanine✔ (1) 
3. Phosphate✔ (1) 
4. Hydrogen✔ bond  (1) 

1.4.4 Double helix✔ (1) 
1.4.5 DNA replication✔ (1) (9)
1.5
1.5.1 Phylogenetic✔ (1) 
1.5.2

1. 5✔ (1) 
2. 4✔ (1) 

1.5.3 (Paranthropus) robustus✔ and (Paranthropus) boisei✔(2) 
1.5.4 

1. Accept any value in the range 4,3 to 4,5 million years   ago✔/mya (1) 
2. 1 mya✔ (1) 

1.5.5 

1. Homo neanderthalensis✔ (1) 
2. Homo habilis✔ (1) (9)

TOTAL SECTION A: 50 

SECTION B
QUESTION 2
2.1
2.1.1 Homologous chromosomes✔ (1) 
2.1.2 45✔(1) 
2.1.3 Gonosomes✔(1) 
2.1.4 The presence of a Y chromosome✔/XY chromosome (1) 
2.1.5 Chromosome✔mutation (1) 
2.1.6 

• Non-disjunction occurred✔/A homologous pair of chromosomes failed to separate
• at position 21✔
• during Anaphase✔
• resulting in one gamete with 24 chromosomes✔/an extra  chromosome/2 chromosomes at position 21
• The fertilisation of this gamete with a normal gamete✔/gamete  with 23 chromosomes/1 chromosome at position 21
• results in a zygote with 47 chromosomes✔
• There are 3 chromosomes✔/an extra chromosome at position  21/ this is Trisomy 21 Any 6 (6) (11)

2.2
2.2.1 

1. 3✔
2. 3✔  

2.2.2  

1. Hearing✔/Normal 
2. Hh✔

2.2.3 

• Lyall inherited one recessive allele✔
• from each parent✔

2.2.4 
 (7)  (13)
2.3
2.3.1 

• Fossil✔/ ‘the first fossil’
• Cultural✔/ ‘stone tools’/’animal remains’ (2)
  (Mark first TWO only) 

2.3.2 83 000 years✔(1) 
2.3.3 Australopithecus✔(1) 
(Mark first ONE only) 
2.3.4

• The jaw was more prognathous✔/protruding and
• larger✔than in humans
• The jaw was more rectangular✔
• The palate shape was less rounded✔/U-shaped/rectangular
• The canines were larger✔
• Large spaces✔/diastema between the teeth Any 3 (3)
  (Mark first THREE only)

2.3.5

• A more forward✔position
• of the foramen magnum✔(2)
  (Mark first ONE only) 

2.3.6

• Opposable thumbs✔
• Bare fingertips✔
• Nails✔instead of claws
• Pentadactyl✔hand Any 2 (2)
  (Mark first TWO only) 

Guideline for assessing the table 

(5) (16) [40]

QUESTION 3 
3.1 
3.1.1 Blood group A✔
3.1.2

• 40 ✔ x 5 000 000 ✔
  100             1
  = 2 000 000✔/2 million 

3.1.3

• The alleles IAand IB✔
• are equally dominant✔  

3.1.4

• When phenotypes fit into separate or distinct categories✔
• with no intermediate phenotypes✔

3.1.5

1. i✔
2. Blood group O✔

3.2
3.2.1

• It is characterised by long periods of little or no change✔
• alternating with short periods of rapid change✔
• during which new species may form✔ 

3.2.2 They contain toxins✔ which kill the snakes OR Too large✔ to be swallowed Any 1 
3.2.3

• Having a smaller jaw✔
• means cane toads cannot be consumed✔
• thereby protecting the snakes from ingesting the toxins✔ 

3.2.4

• Since the snakes' jaws were used less ✔/not used
• the snakes developed smaller jaws✔
• This characteristic (of a smaller jaw) was inherited by the   offspring✔
• Over many generations the jaw of the snake became smaller✔  

3.3
3.3.1 Dihybrid✔ cross 
3.3.2

1. Red✔
2. Short✔
3. Red✔ and Tall✔
4. ffhh✔✔

3.3.3

• When two organisms with pure breeding✔
• contrasting traits✔are crossed 
• all the individuals of the F1 generation will display the dominant   trait✔
  OR
• If an organism is heterozygous✔
• the dominant allele✔
• will determine the phenotype✔

3.4
3.4.1

1. Exposure to insecticide✔
2. Number of insects that survived✔/survival rate of insects 

3.4.2

• Sample size✔/300 insects 
• Size of containers✔
• Conditions✔
• Concentration of insecticide✔
• Volume of insecticide✔
• Time period✔/24 hours Any 3
  (Mark first THREE only) 

3.4.3

• They only conducted the investigation once✔/did not repeat
• They used a small sample/only 300 insects✔  
• They used only two storage bins✔ Any 2
  (Mark first TWO only) 

3.4.4

• Insects that were previously exposed to the insecticide had a  higher survival rate✔✔
  OR
• Insects that were not previously exposed to the insecticide had a  lower survival rate✔✔ [40] 

TOTAL SECTION B: 80

SECTION C    
QUESTION 4 
MUTATIONS AND PROTEIN SYNTHESIS 

•  A mutation is a change in the nucleotide/nitrogenous base sequence✔
• of a DNA molecule✔/a gene 
• since mRNA is copied from the DNA molecule✔
• during transcription✔
• This will result in a change in the codons✔
• As a result, different tRNA✔ molecules
• carrying different amino acids✔ will be required
• The sequence of amino acids changes✔
• resulting in the formation of a different protein✔
• If the same amino acid ✔is coded for
• there will be no change✔in the protein structure Any 9 (9) 

MUTATIONS AND EVOLUTION IN PRESENT TIMES 

• In a population of insects✔/bacteria/HI viruses/Galápagos' finches
• mutations are a source of variation✔
• which may make some organisms more resistant✔/better suited
• to insecticides✔/antibiotics/antiretroviral medication/ drought 
• Those individuals that are not resistant/suited will die✔ whereas
• those that are resistant/ well suited, will survive✔
• to pass the resistant allele/resistance on to their offspring✔
• This is known as natural selection✔
• As a result, individuals of the future generations will be resistant to the insecticides✔/antibiotics/antiretroviral medication/adapted to drought Any 8  (8) 

Content (17) 
Synthesis (3) (20) 

ASSESSING THE PRESENTATION OF THE ESSAY 

TOTAL SECTION C: 20 
 GRAND TOTAL: 150