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.

MEMORANDUM

SECTION A
QUESTION 1
1.1
1.1.1 C
1.1.2 B
1.1.3 B
1.1.4 D
1.1.5 B
1.1.6 C
1.1.7 B
1.1.8 D (8 x 2) (16)
1.2
1.2.1 Vasodilation
1.2.2 Hypothalamus
1.2.3 Negative feedback
1.2.4 Parasympathetic system
1.2.5 Aldosterone
1.2.6 Synapse
1.2.7 Placenta (7 x 1) (7)
1.3
1.3.1 None
1.3.2 A only
1.3.3 A only (3 x 2) (6)
1.4
1.4.1

1. A (1)
2. E (1)
3. B (1)
4. F (1)

1.4.2 Spinal cord (1)
1.4.3 Reflex action (1)
1.4.4 Brain and the spinal cord (2)
1.4.5

1. C (1)
2. D (1)

1.5
1.5.1 

1. A – Vagina (1)
2. B – Cervix (1)
3. F – Uterus (1)

1.5.2

1. C endometrium (2)
2. D Ovary (2)
3. E Fallopian tube (2)

1.5.3 Sperm will not be able to fertilise the ovum / sperm will not be able to reach ovum and cause fertilisation (1)
1.5.4 Both ovaries release ova alternately (1)
TOTAL SECTION A: 50

SECTION B
QUESTION 2
2.1
2.1.1

1. Prophase I (1)
2. Metaphase I (1)

2.1.2

1. A – Centromere (1)
2. B – Homologous chromosomes / Chromosomes (1)
3. D – Centriole (1)

2.1.3

• Homologous chromosomes lie side by side
• Chromatids from the paternal and maternal chromosomes
• Establish contact points called chiasmata and
• Exchange genetic material between chromatids and
• This is known as crossing over (Any 4) (4)

2.1.4

• Homologous chromosomes randomly arrange themselves
• on either side of the equator and this
• leads to the formation of new combinations of genetically
• different chromosomes
• in the daughter cells (gametes) causing variation* in the next generation (1* compulsory point + any 2) (3)

2.2
2.2.1 Altricial development (1)
2.2.2

• Eyes closed
• no down feathers covering the body / bodies naked
• unable to feed themselves
  (Mark first THREE only) (3)

2.2.3

• Complete dependence on parents until fully developed
  OR
• unable to defend/move
• therefore, they are an easy target for predation (Any 1) (1)

2.2.4

• The egg yolk that supplies nutrients to the developing embryo is small therefore,
• the hatchlings are unable to develop fully before hatching (2)

2.3
2.3.1 Long/far-sightedness (Hypermetropia) (1)
2.3.2

• Eye ball is too rounded
• due to the inability of the lens of the eye to become more convex
• therefore, the image of the near object that falls on the retina is blurred while
• the most clearly focussed image falls behind the retina(4)

2.3.3

• It can be corrected with a convex lens
  (Mark first ONE only) (1)

2.3.4

• The radial muscles of the iris contract
• the circular muscles relax
• the pupil dilates
• the amount of light entering the eye is increased (4)

2.4
2.4.1 Luteinizing hormone (LH) (1)
2.4.2 The highest level of LH causes ovulation (1)
2.4.3 13th day of the cycle (1)
2.4.4

• High level of oestrogen / an increase in level of oestrogen causes the endometrium to become more
• vascular and spongy/thicker (2)

2.4.5 Progesterone (1)
2.4.6

• The maintenance of high levels of progesterone / hormone B after 28 days indicates pregnancy
• hormone B / progesterone is required to maintain pregnancy / maintain the endometrium (2)

2.4.7

• High levels of progesterone inhibit the secretion of FSH in order to stop the development of new follicles and
• cause ovulation / no new ova produced
• during pregnancy / disrupts pregnancy (3)

[40]

QUESTION 3
3.1
3.1.1 Thyroid gland (1)
3.1.2 Treatment of thyroxin / substance tadpoles were treated with (1)
3.1.3

• Quantity of NaOH and thyroxin treatment
• Time of treatment/ feeding
• Time of collecting data
• Size of tadpoles
• Type of nutrients
• Quantity of nutrients
• Level of activity / area of captivity
• Environmental conditions
• Method of determining the body mass
  (Mark first TWO only) (Any 2) (2)

3.1.4 The initial body mass taken before the treatment (1)
3.1.5

• High levels of thyroxin in the body
• increase the rate of metabolism
• More glucose will be oxidised / more of their fuel reserves are used up
• to release more energy / allowing them to be more active
• this leads to drop in the body mass (4)

3.1.6

• When the thyroxin level drops below normal limits
• pituitary gland / hypophysis is stimulated
• Pituitary gland secretes more TSH
• High TSH level stimulates the thyroid gland
• The thyroid gland secretes more thyroxin
• The thyroxin level thus increases
• Thyroxin level returns to normal (5)

3.2
3.2.1

1. B – Medulla oblongata (1)
2. C – Corpus callosum (1)
3. E – Cerebellum (1)

3.2.2

1.                    
   • It conducts impulses between the brain and the receptors / effectors
   • Serves as a reflex centre for actions such as blinking, sneezing, coughing etc. (Any 1) (1)
     (Mark first ONE only)
2.                        
   • Cerebro-spinal fluid in the central canal supplies nutrients and oxygen for nerve cells / removes CO₂ and waste products from the nerve cells / protects the brain and spinal cord against physical injury
     (Mark first ONE only) (1)

3.2.3

1.                        
   • During a haemorrhage, the blood leaks out of the blood capillaries
   • and this disrupts the supply of oxygen and nutrients to the nerve cells / removal of CO₂ and metabolic waste causing them to die / causes excessive pressure (3)
2.                      
   • Loss of sensation / consciousness / unable to process impulses from sense organs
   • loss of higher intellectual abilities such as memory, judgement, reasoning. etc.
   • unable to initiate voluntary muscular actions (3)

3.3
3.3.1 Auxin (1)
3.3.2 Auxin is present / produced at the growing tip of stem or root (1)
3.3.3 To cancel the effect of unilateral light on plumule growth / to show that the light has no effect on the upward bending of plumule / to exclude a phototropic response (1)
3.3.4 When a plumule is placed horizontally:

• Auxins are attracted by gravity
• There is a high concentration of auxins on the lower side of the plumule
• which stimulates growth / cell elongation / cell division on the lower side
• There is a low concentration of auxins on the upper side of the plumule
• which inhibits growth / cell elongation / cell division on the upper sides
• The lower side of the plumule grows faster / uneven growth occurs causing the plumule to grow/ bend upwards
• The plumule grows away from gravity*/ the plumule is negatively geotropic
  1* Compulsory mark + (Any 3) (4)

3.3.5 The germinating seed is attached to the disc of rotating clinostat (1)
3.4
3.4.1

• Has a protective function
• Acts as a climate control system for the testes / temperature control
  (Mark first TWO only) (2)

3.4.2 Epididymis (1)
3.4.3

• Fertility is reduced
• because the temperature is always high
• This will lead to production of abnormal sperms / fewer sperm are formed / proteins in the cells that form the sperm will denature
  OR
• Fertility is reduced
• because the pressure is increased / reducing circulation of the blood
• This will lead to the production of abnormal sperm / Fewer sperms are formed (3)

3.4.4 Take regular breaks while driving long distances (1)
[40]
TOTAL SECTION B: 80

SECTION C
QUESTION 4
The process that led to an increased breathing rate:

• The adrenal gland
• secretes more adrenalin into the blood
• An increased level of carbon dioxide in the surrounding area due to the heavy smoke
• causes carbon dioxide levels in the blood to increase above the normal levels
• Receptor cells in the carotid artery in the neck are stimulated
• to send impulses to the medulla oblongata in the brain
• Medulla oblongata stimulates breathing muscles (intercostal muscles and diaphragm)
• and heart
• Breathing muscles contract more actively
• Increases the rate and depth of breathing
• The heart beats faster
• More carbon dioxide is taken to and exhaled from the lungs
• causing the breathing rate to increase
  Max. 10 (10)

Restoring balance
Balance is achieved in the following way:

• The maculae
• in the utriculus and sacculus and
• the cristae
• in the semi-circular canals are stimulated
• They generate impulses
• which are transmitted through the auditory nerve
• to the cerebellum
• where they are interpreted
• Impulses are transmitted via the motor neuron
• to skeletal muscles
• to restore balance

Max. 7 (7)
Content (17)
Synthesis (3)
(20)

ASSESSING THE PRESENTATION OF THE ESSAY

TOTAL SECTION C: 20
GRAND TOTAL: 150