LIFE SCIENCES PAPER 1
GRADE 12
MEMORANDUM
SEPTEMBER 2016
NATIONAL SENIOR CERTIFICATE

SECTION A
QUESTION 1
1.1
1.1.1 B ✓✓
1.1.2 B ✓✓
1.1.3 A ✓✓
1.1.4 A ✓✓
1.1.5 B ✓✓
1.1.6 D ✓✓
1.1.7 A ✓✓
1.1.8 B ✓✓
1.1.9 C ✓✓
1.1.10 A ✓✓
(10 x 2)
(20)
1.2
1.2.1 Axon ✓
1.2.2 Receptors/Sense organs ✓
1.2.3 Carbon footprint ✓
1.2.4 Deforestation ✓
1.2.5 Biodiversity ✓
1.2.6 Autonomic nervous system ✓
1.2.7 Glucagon ✓
1.2.8 Blastocyst ✓/Blastula
1.2.9 Meninges ✓
1.2.10 Cerebellum ✓ (10 x 1) (10)
1.3
1.3.1 None ✓✓
1.3.2 A only ✓✓
1.3.3 B only ✓✓ (3 x 2) (6)
1.4
1.4.1 Reflex action✓(1)
1.4.2

1. A ✓ (1)
2. F ✓ (1)

1.4.3 D Synapse ✓ (1)
1.4.4

1. E ✓ (1)
2. B ✓ (1)
3. C ✓ (1)

1.5
1.5.1

1. F ✓ (1)
2. D ✓ (1)
3. E ✓ (1)
4. C ✓ (1)

1.5.2

1. 1 Centromere ✓ (1)
2. 2 Chiasmata ✓ (1)
3. 3 Chromatid ✓ (1)

TOTAL SECTION A: 50

SECTION B
QUESTION 2
2.1
2.1.1

1. A Seminal vesicle ✓
   Produces a nutrient-rich ✓fluid to energise sperm cells (2)
2. C Vas deferens✓/Sperm duct
   Transports the sperm ✓ from the epididymis to the ejaculatory duct/urethra. (2)

2.1.2 B Prostate gland ✓ (1)
2.1.3

1. Part E ✓ (1)
2. Part D ✓ (1)

2.1.4 Penis ✓ (1)
2.1.5 No sperm can be released through ✓
the penis which will result in no fertilisation ✓
to take place and no offspring ✓ will be produced/no reproduction. (3)
2.2
2.2.1
Boys have faster reaction✓ time than the girls. ✓ OR
Girls have lower reaction✓ time than the boys. ✓ OR
Both boys and girls✓ have the same reaction time. ✓(2)
2.2.2

1. Reaction time ✓ (1)
2. Gender ✓ (1)

2.2.3

• Each trial was repeated for 5 times for each of the participants ✓
• Relatively large sample size was taken ✓ (about 67% of the class participated in the trials) (2)

2.2.4

• Same group of learners used ✓
• Same person dropping the ruler✓
• Same meter ruler ✓
• Same time of the day ✓ (Any 2 x 1) (Mark first two only) (2)

2.2.5 Many attempts gives the participants a reasonably good practice session and therefore, their reaction time improves with practice. ✓ (1)
2.3
2.3.1 A site where (solid wastes) domestic and industrial wastes are buried. ✓ (1)
2.3.2 R120 000 000 ✓/one hundred and twenty million rands (1)
2.3.3

• Energy can be saved ✓by recycling because the raw materials used to manufacture certain waste materials such as glass do not have to be dug from the earth and melted together at very high temperatures.
• Reduces environmental pollution ✓because manufacturing of new products use large quantities of fossil fuels as a source of energy. (2)

2.3.4

• Re-use shopping bags✓/using an item for the same purpose more than once.
• Reduce ✓/avoiding the purchase of items that have unnecessary packaging around them. (2)

2.3.5

• Decomposition of organic ✓/household waste
• causes the release of greenhouse gases ✓ such as CO₂ and methane
• that trap more heat from the sun ✓causing increased global warming
• cause enhanced greenhouse effect. ✓ (Any 2 x 1)(2)

2.3.6

Mark allocation of graph:

(6)
NOTE:
If a line graph is drawn – marks will be awarded for the “title and labels for X and Y axis” only
If a histogram is drawn – marks will be lost for the “type of graph and correct scale” only

2.3.7

1. plastic (1)
2. cans (1)

2.4
2.4.1

• A karyotype is a computerised diagram ✓ of all the chromosomes. ✓
• Complete set of chromosomes in a cell (during metaphase) showing the number, size and shape✓ of all the chromosomes.
  (Any 1 x 2) (2)

Related Items

2.4.2 Eutrophication is the increase in the amount of nutrients ✓ from various sources, washed into the rivers and water reservoirs ✓ causing excessive growth ✓ of aquatic weeds ✓ and algae. ✓ (Any 2 x 1) (2)
[40]

QUESTION 3
3.1
3.1.1 Tropism ✓ (1)
3.1.2 Auxin ✓ (1)
3.1.3

• Brings about bending reaction in plants known as tropism ✓
• Promote cell division ✓
• Responsible for cell elongation ✓
• Responsible for apical dominance ✓
• Promote root development ✓ (Any 2 x 1) (Mark first only) (2)

3.1.4 It promotes cell elongation ✓ at the growing tip of the stem. (1)
3.1.5

• Under the influence of gravity ✓ the auxins tends to accumulate on the lower side of the root. ✓
• The growth on the lower side is inhibited ✓ by the increased concentration ✓ of auxins✓
• On the upper side of the root the auxin concentration is less, ✓ these cells therefore elongate more  causing
• the root to bend and grow downwards. ✓ (6)

3.2

• When the level of thyroxin is too low ✓
• the pituitary gland is stimulated ✓
• to secrete more TSH ✓ and
• the increased level of TSH ✓ causes
• the thyroid gland ✓
• to secrete more thyroxin ✓ and
• thyroxin level of the blood is raised to the normal level ✓
• When the thyroxin level of the blood is too high ✓
• the pituitary gland secretes less TSH ✓
• little or no thyroxin is secreted ✓ and
• the thyroxin level is thus reduced to normal limits. (6)

3.3
3.3.1 As humans get older, there is a progressive decline in the secretion of growth hormone. ✓✓ (2)
3.3.2 The amounts of growth hormone secreted between the ages of 13 and 19 is comparatively higher ✓ than the amounts of hormone secreted during the rest of the life of the person. (1)
3.3.3

1. Gigantism ✓ (1)
2. Dwarfism ✓ (1)

3.3.4

• The rapid development of stronger muscles ✓
• Growth in size and mass of skeletal system ✓ (Any 1 x 1)(1)

3.4
3.4.1

• The endocrine disrupters/malfunctioning of endocrine glands
• Life style/life style variations/driving a vehicle for prolonged periods (Any 1 x 1) (1)

3.4.2

• Long distance drive extends the period sitting at a fixed position causing male reproductive organ to remain tightly squeezed between the thighs for a considerable period of time. ✓
• As the temperature rises ✓ in the area, the scrotum is unable to pull the testis away from the body due to lack of spacing,
• hence the testes remain in contact with the body and maintain a higher temperature causing a disruption of spermatogenesis. ✓ (3)

3.4.3 The low sperm count reduces the chances of fertilisation✓ and may lead to male infertility. ✓ (2)
3.4.4

• Use of very tight under wear ✓
• sitting in a hot water tub for a long time as daily routine. ✓ (Any 1 x 1) (1)

3.5
3.5.1 This is the process of maintaining the internal environment ✓ at a constant optimal state ✓ (2)
3.5.2 Skin ✓ (1)
3.5.3

• Enzymes regulate normal functioning of the body.✓
• High temperatures cause the enzymes to denature ✓
• and low temperatures inactivate ✓ enzymes temporarily. (Any 2 x 1) (2)

3.6 3.6.1

• High levels of salts in the body fluids causes the secretion of aldosterone ✓
• from the adrenal gland ✓
• decreases. ✓
• Less sodium is thus reabsorbed ✓by the blood capillaries
• allowing more sodium to be excreted ✓
• The amount of sodium in the blood decreases back to normal✓ (4)

3.6 .2 ADH ✓ (1)
[40]

TOTAL SECTION B: 80

SECTION C
QUESTION 4
Pupillary mechanism ✓

• The circular muscles of the iris contract. ✓
• The radial muscles relax. ✓
• The pupil constricts. ✓
• The amount of light entering the eye is reduced. ✓ (Max 4) (4)

Accommodation ✓ for near vision

• Ciliary muscles contract. ✓
• The suspensory ligaments become slack. ✓
• The tension on the lens decreases.✓
• The lens becomes more convex. ✓
• The refractive power of the lens is increased. ✓
• A clear image of the near object is now formed on retina. ✓ (Max 5) (5)

Role of adrenalin
The excitement and panic triggered the secretion of hormone adrenalin causing:

• An increase in the rate of breathing ✓ so that more oxygen is obtained quickly. ✓
• Liver to convert more glycogen to glucose. ✓
• An increase in the rate of heart beat and the blood pressure✓ so that oxygen, glucose and thyroxin can be carried away quickly to the skeletal muscles and brain. 
• Dilation of blood vessels of muscles, heart and brain✓ so that more blood can be taken to these parts. ✓
• Constriction of blood vessels of digestive system and skin ✓ so that less blood is sent to these parts and more blood becomes available for heart, brain and skeletal muscles. ✓
• An increase in the tone of skeletal muscles ✓ so that they can function more effectively. ✓
• Increases the metabolic rate of the cells in the brain and skeletal muscles so that more energy is released for muscular activity and clear thought. ✓ (Any 4 x 2)(8)
  
  

ASSESSING THE PRESENTATION OF THE ESSAY

Content: (17)
Synthesis: (3)

TOTAL SECTION C: 20
GRAND TOTAL: 150