LIFE SCIENCES PAPER 1
GRADE 12
NATIONAL SENIOR CERTIFICATE
SEPTEMBER 2018

SECTION A
QUESTION 1
1.1 1.1.1 C ✓✓
1.1.2 A ✓✓
1.1.3 D ✓✓
1.1.4 C ✓✓
1.1.5 B ✓✓
1.1.6 C ✓✓
1.1.7 A✓✓
1.1.8 C ✓✓
1.1.9 D ✓✓
1.1.10 C ✓✓
(10 x 2) (20)
1.2 1.2.1 Metaphase II ✓
1.2.2 Acrosome ✓
1.2.3 Insulin ✓
1.2.4 Homeostasis ✓
1.2.5 Follicle Stimulating Hormone ✓ / FSH
1.2.6 Cytokinesis ✓
1.2.7 Fallopian tube ✓/ Oviduct
1.2.8 Greenhouse effect ✓
1.2.9 Blastocyst ✓/Blastula
1.2.10 Amniotic fluid ✓ (10 x 1) (10)
1.3 1.3.1 A only ✓✓
1.3.2 A only ✓✓
1.3.3 B only ✓✓
1.3.4 A only ✓✓ (4 x 2) (8)
1.4 1.4.1 Sweat gland ✓ (1)
1.4.2 Diagrams 2 ✓ and 3 ✓ (2)
1.4.3 Diagram 3 ✓ (1)
1.4.4 Diagram 1 ✓ (1)
1.4.5 Hypothalamus ✓ (1)
1.5 1.5.1 Fishes ✓ (1)
1.5.2 Chimpanzees, ✓ Humans, ✓Crocodiles✓
(Mark the first TWO only) (2)
1.5.3 Snakes✓,Chickens✓
(Mark the first ONE only) (1)
1.5.4 Chimpanzees, ✓Humans, ✓ Whales ✓
(Mark the first TWO only) (2)
TOTAL SECTION A: 50

SECTION B
QUESTION 2
2.1 2.1.1

1. B ✓ (1)
2. C ✓ (1)

2.1.2

• No vibrations / no transmission of vibrations to the oval window✓
• hence no pressure waves created in the fluid of the cochlea✓
• hearing receptors not stimulated✓
• no impulses reach the cerebrum.✓ (Any 3) (3)

2.1.3

1. E ✓ B ✓ (2)
2. C ✓ (1)

2.1.4

• No impulses will be transmitted to the cerebellum ✓and therefore,
• no sense of balance will be achieved. ✓/ Speed and direction of head ✓movement will not be interpreted to maintain body balance.
  (Any 2) (2)

2.2
2.2.1

1. C ✓ (1)
2. A ✓ (1)

2.2.2

1. • The sperm will not be able to reach the urethra ✓
   • therefore, no sperm in semen ✓/ ejaculate/released during ejaculation.
   • hence no sperms transferred to vagina ✓
   • and no fertilisation will take place. ✓ (Any 3) (3)

2.3 2.3.1

1. Sclera✓ (1)
2. Yellow spot ✓ / Fovea centralis / fovea (1)
3. Choroid ✓ (1)

2.3.2 B ✓ and C ✓ (2)
2.3.3

• Suspensory ligaments are slack✓
• Lens is more convex✓
• Light is refracted more ✓
• Image forms in front of retina ✓/ is blurred (Any 3) (3)

2.3.4

• The powerful laser rays damage the photo-receptors ✓/ rods and cones in the retina
• cannot convert light stimulus to impulses ✓
• no impulses send to cerebrum via optic nerve ✓ (Any 2) (2)

2.4 2.4.1 Growth hormone ✓ (1)
2.4.2 Included many children ✓/ large sample (1)
2.4.3 175 x 100 = 41.18% or 41.2% (2)
         425
2.4.4

Marking guideline

(6)
2.5 2.5.1 The measure of the total amount of greenhouse gas emissions ✓ of an individual, population or company per year. ✓ (2)
2.5.2 By measuring the consumption of fuels such as petrol, diesel and oil. ✓ (1)
2.5.3

• Educate people about the effects of greenhouse gas emissions.✓
• Penalise companies whose carbon footprint is too large ✓
• Reforestation to remove excess carbon dioxide from the atmosphere ✓
• Use alternative sources of energy. ✓ (e.g. solar energy etc)
• Introduce programs to promote reusing and recycling by people. ✓

(Mark first TWO only) (Any 2) (2)
[40]

QUESTION 3
3.1
3.1.1

• Umbilical artery ✓
• Umbilical vein ✓ (Any order) (2)

3.1.2

(Mark the first ONE only) 1 x 2 + 1 mark for the table (3)
3.1.3 Diffusion ? (1)
3.1.4

• The placenta will not be fully functional ✓ / there is less surface area for diffusion and therefore,
• less oxygen/ nutrients will be supplied to foetus ✓
• leading to under development ✓
• causes the accumulation of metabolic waste products ✓ in the foetus/less diffusion of wastes to the mother
• causing blood to be highly toxic ✓and this
• results in the miscarriage / death of the foetus ✓(Any 3) (3)

3.2 3.2.1 High/low levels of abscisic acid in the seeds inhibits/promotes germination ✓
OR
Abscisic acid has no effect on germination.
OR
Low/high levels of abscisic acid in the seeds inhibits/promotes germination (2)
3.2.2

1. The percentage germination of seeds ✓ (1)
2. Presence /absence of abscisic acid ✓ (1)

3.2.3

• Equal number of seeds used in tray A and B ✓
• Same soil used in both trays ✓
• Seeds were exposed to same environmental conditions ✓/ examples of same environmental conditions
• Data collected from both trays at the same time ✓

(Mark the first TWO only) (Any 2) (2)
3.2.4 0 ng/g ✓/ anything less than 10 ng/g (1)
3.3 3.3.1 Metaphase 1 ✓ (1)
3.3.2 Homologous pairs of chromosomes are arranged on the equator. ✓ (1)
3.3.3

• During prophase1✓
• chromatids of homologous chromosomes over lap at chiasmata✓/ chiasma
• and exchange genetic information ✓ between them
• This process is called crossing over. ✓ (Any 3) (3)

3.3.4

• They have the same length ✓
• Centromeres at the same position
• Have alleles for the same gene at the same locus. ✓

(Mark the first TWO only) (2)
3.4 3.4.1 River B ? (1)
3.4.2 The indicator changed colour from red to cloudy yellow. ✓ (1)
3.4.3 - Faeces of people / raw sewage gets into the river ✓/ burst sewage pipe releases raw sewage into the river. (1)
3.4.4

• E. coli live in the human intestine ✓
• 37°C is body temperature ✓
• therefore, it is the optimal temperature ✓for these bacteria for growth and multiplication. (Any 2) (2)

3.4.5

• decrease oxygen in water ✓
• causes decomposition ✓
• which uses oxygen ✓ (Any 2) (2)

3.5 3.5.1 The use of a natural enemy ✓/insect/disease to control its number/ reduce numbers of a pest species. ✓ (2)
3.5.2 As the biological control agent’s numbers increase, the number of the pest decreases.✓✓ (2)
3.5.3

• No harmful chemicals would be used ✓
• which could cause possible damage to the crops ✓/ environment / cause land, water and air pollution and primary consumers/organisms which fed on the crops.

OR

• No damage to rest of environment ✓
• because research is done to ensure the control agent will not become a pest. ✓ (2)

3.6
3.6.1

• Blood glucose level remained very high for a long period of time✓/ Blood glucose level did not drop to its initial value (baseline value) after 2 hours.
• Initial glucose level at time 0 minute is higher in patient 2 than patient 1. ✓ (2)

3.6.2

• Patient 1 is able to convert glucose into glycogen and store in the liver and muscles ✓
• This glycogen will be converted to glucose when the blood glucose level drops below its normal level. ✓ (2)

[40]
TOTAL SECTION B: 80

SECTION C
QUESTION 4
Reflex action

• The (pain) receptors in the skin are stimulated ✓
• and converted stimulus into an impulse ✓
• The impulse travels via the sensory neuron ✓
• to the spinal cord ✓
• In the spinal cord, the sensory neuron makes a synaptic contact ✓
• with the interneuron. ✓
• Which makes synaptic contact with motor neuron ✓ and
• transmits the impulse
• to the muscles of the leg ✓/ effectors
• The muscles respond by contracting ✓
• causing him to lift the leg ✓
• This is known as reflex action. ✓
• The path of the impulse along each neuron is from dendrite ✓
• to cell body ✓
• to axon ✓ (Any 9) (9)

Significance

• The reflex action allows for al rapid ✓ /quick
• involuntary response ✓ / without thinking about it
• to the stimulus ✓
• to prevent damage to the body ✓ (Any 3) (3)

Neural pathway

• Photo-receptors/rods and cones✓
• in the retina are stimulated ✓
• by the light/ stimulus
• Nerve impulses are generated ✓ and
• transmitted via optic nerve ✓
• to the cerebrum ✓
• where the image of the crab is interpreted✓/  vision occurs. (Any 5) (5)

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

ASSESSING THE PRESENTATION OF THE ESSAY

TOTAL SECTION C: 20
GRAND TOTAL: 150