Download secondary school improvement programme - Sci

1
SECONDARY SCHOOL IMPROVEMENT
PROGRAMME (SSIP) 2015
GRADE 12
SUBJECT:
LIFE SCIENCES
TEACHER NOTES
(Page 1 of 86)
© Gauteng Department of Education
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TABLE OF CONTENTS
SESSION NO
TOPIC
PAGE
5
Genetics and Inheritance Part 1
3 - 23
6
Genetics and Inheritance Part 2 and
Responding to the environment - Humans:
Nervous system Part 1
24 - 41
7
Responding to the environment - Humans:
Nervous system Part 2 and
Eye and Ear
42 - 58
8
Consolidation
58 - 68
9
Consolidation
69 - 78
10
Consolidation
79 - 86
© Gauteng Department of Education
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SESSION NO: 5
TOPIC:
GENETICS AND INHERITANCE PART 1
Teacher note: Learners MUST understand the link between meiosis and genetics.
During the crossing over in prophase I of meiosis, chromosomes share information
and then during metaphase I, separate randomly. This determines the combination
of chromosomes and genes that you have as an individual. Genetics determines
individual variation (to be different) and survival of the fittest. They MUST have a
clear understanding of the genetic terminology in order to study genetics and answer
genetic problems. Mendel’s Laws are very important - understand the concepts of
dominance and how this plays a role in monohybrid crosses (mono = one = one
characteristic or trait). Be aware of confusing the word ‘cross/ crossing’ with ‘crossing
over’ in Meiosis. You cross individuals and calculate the chances of a characteristic
or trait being in the offspring. Learners must be clear of the difference between these
two terms. Questions on blood group inheritance and sex determination are often
asked. The more examples of genetic crosses that they do, the better they will do.
Pedigree diagrams are a popular way to express family history and are often asked
in exams. Make sure they know how to answer them. There are basically FOUR
crosses. If they know these crosses, they will be okay.
1.
2.
3.
4.
Introduce session – 5 minutes (and go over basic idea as per the above
introduction)
Typical exam questions and solutions – 50 minutes
(Questions that are not completed must please be included with Homework)
Notes on Content – 15 minutes
Answer/memo discussion – 20 minutes
SECTION A: TYPICAL EXAM QUESTIONS
QUESTION 1: Multichoice
7 minutes
(Taken from various sources)
(Note: When answering multi-choice questions:
1. Read the question while covering the answers.
2. Think of the correct answer.
3. Look for your answer.
4. Write the letter down on your answer sheet.
BUT: If you do not know the answer after point 1 and 2, then:
3. Look at the options.
4. Try to think of why an option is wrong for the question and cross it out. If
there is an option that you don’t know, write a ? next to this option.
5. If you still do not know the answer, then select the ? option)
(Reminder: there are only 4 basic types of crosses. Make sure you are able to
use them properly. Do a quick cross in pencil, next to the relevant question to
find the correct answer)
1.
The term for the physical appearance of an organism due to the genetic
composition:
© Gauteng Department of Education
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A
B
C
D
heterozygous
genotype
homozygous
phenotype
2.
When the allele genes on homologous chromosomes differ, the organism is
A
homozygous
B
dominant
C
heterozygous
D
recessive
3.
The genotype of a plant that results from a cross between a plant with red
flowers (RR) and white flowers (rr) will be:
A
RR
B
Rr
C
rr
D
rR
4.
Choose the correct cross if the result is 50% homozygous dominant and 50%
heterozygous in the F1 generation:
A
Bb xbb
B
BB x Bb
C
BB x bb
D
Bb x Bb
5.
Two white heterozygous cats were crossed where white fur is dominant over
black fur. Choose the correct phenotype of the F1 generation:
A
25% white and 75% black
B
50% black and 50% white
C
25% black and 75% white
D
100% white
6.
A heterozygous red flower plant was crossed with a homozygous white flower
plant and yielded 300 new plants. What number of the new plants will carry
white flowers?
A
150
B
225
C
300
D
196
7.
The babies of a purebred while rabbit were crossed with a purebred black
rabbit. Black hair dominates over white hair. The offspring of the F2will be:
A all black
B all white
C 75% black and 25% white
D 75% white and 25% black
(7 x 2 ) [14]
© Gauteng Department of Education
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QUESTION 2:
11 minutes
(Taken from DoE November 2008 Paper 1)
(The following question is based on a pedigree diagram. Please see the
content summary for hints to answer questions on pedigree diagram. In this
diagram, the family history is shown as a schematic diagram. Always identify
the recessive individuals first. Write their trait symbols next to the number
e.g.: S = straight hair and s = wavy hair. So ss = homozygous for the
recessive trait)
The eight items below are based on the pedigree diagram which shows the
phenotypes of offspring from wavy-haired parents. Write down the letters A, B, C or
D according to the following key:
A - if the statement is TRUE
B - if the statement is FALSE
C - if there is a 25% chance that the statement is TRUE
D - if there is a 50% chance that the statement is TRUE
P
1
2
5
6
F1
3
4
9
10
7
8
11
12
F2
= straight
= wavy
= curly
2.1.
2.2.
2.3.
2.4.
2.5.
2.6.
2.7.
2.8.
Wavy hair is dominant.
(1)
Individual 1 is homozygous
(1)
If individual 6 married a woman with straight hair, all of the offspring would
have straight hair.
(1)
Individual 4 is homozygous.
(1)
One of the parents of 2 had the same genotype as 2.
(1)
If 10 married someone with wavy hair, the first child would have wavy hair (1)
If 1 and 2 had another child, the child would have curly hair.
(1)
If 3 and 4 had more children than those shown, they might have straight
hair.
(1)
[8]
© Gauteng Department of Education
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QUESTION 3:
8 minutes
(Taken from DoE November 2009 Paper 1)
Fur colour in mice is controlled by a gene with two alleles. A homozygous mouse with
black fur was crossed with a homozygous mouse with brown fur. All the offspring
had black fur.
Using the symbols B and b to represent the two alleles for fur colour, show as a
Punnit square, a genetic cross between a mouse that is heterozygous for fur colour
with a mouse with brown fur. Show the possible genotypes and phenotypes of the
offspring.
(6)
(Check the content summaries for an example of the 4 possible crosses.
Remember to include P1 and F1, as well as genotype and phenotype, rations
and % in your work.)
QUESTION 4:
5 Minutes
(Taken from DoE November 2008 Paper 1)
People with albinism are unable to produce the dark pigment, melanin, in their skin.
This condition is caused when an individual is homozygous recessive for this
characteristic. The family tree below shows the occurrence of albinism over three
generations.
(This is a pedigree diagram. Always first mark the homozygous recessive
individuals on the diagram before trying to work out the genetic traits for the
other individuals. Albinism is homozygous recessive, so an individual with
albinism will be ‘aa’ and a person who is not an albino will be either ‘AA’ or
‘Aa’.)
4.1.
Indicate whether each of the individuals below could be homozygous
dominant, homozygous recessive or heterozygous:
(a) 1
(2)
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(b) 2
4.2.
(1)
Explain your answer to QUESTION 4.1 (a).
(2)
[5]
QUESTION 5:
6 minutes
(Taken from Free State Prelim 2009)
Sello crosses two pure breeding garden pea plants in the laboratory. Plant A
produces yellow peas and plant B green peas. He knows that the gene, for yellow
peas (Y), is dominant over the gene for green peas (y). The diagram below shows
the results he obtained for two generations of pea plants. Study the diagram and
answer the questions that follow:
(A reminder: yellow is dominant and green is recessive. For a pea plant to
yield green peas, this plant must be ‘yy’ – so homozygous recessive. Also
refer to Mendel’s law of dominance and segregation in the content summary.)
5.1.
5.2.
5.3.
Give the genotype for plant A and plant B.
Provide the phenotypic ratios for the F2 generation.
If Sello allows plant G to self-pollinate, give the phenotype and genotype
of the offspring.
(2)
(2)
(2)
[6]
QUESTION 6:
6 minutes (Taken and adapted from Study & Master Biology Grade 11)
Blood typing can be used to identify a parent in that the blood type can prove that a
person is not the parent of a child rather than determine without question who the
parent is. A, B, AB and O blood groups are the result of three alleles. Allele A and B
are incompletely dominant and O is recessive to both A and B. Should the
discrepancy continue, tissue typing and DNA fingerprinting will be used. Read
© Gauteng Department of Education
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through the following information and answer the questions below:
In a maternity ward of a hospital, two newly born babies were mixed up. One baby is
blood type O and the other is type A. Both mothers believe the baby with blood type
O is their baby. Can you sort it out? On testing the parents’ blood it was found that:
1. Mr. Xhosa is blood group AB and his wife is blood group B
2. Mr. Mbundwini is type A.
Who owns baby ‘O’ and who owns baby ‘A’? Explain / show your reasoning.
[6]
(Remember that in blood groups there are three alleles A, B and O. A and B
are co-dominant over O which is recessive. There must be two of the same
alleles if a recessive trait is present in the individual)
QUESTION 7: 12 Minutes
(Taken from DoE Nov 2011 Paper 1)
Haemophilia is a sex-linked disease caused by the presence of a recessive allele
(Xh). A normal father and heterozygous mother have children.
(Remember: XH is dominant and normal. Xh will carry the recessive
haemophilia gene)
7.1.
7.2.
7.3.
Represent a genetic cross to determine the possible genotypes and
phenotypes of the children of these parents.
What are the chances of the parents having a child that will be a
haemophiliac male?
Explain why the father is not a carrier for haemophilia.
(6)
(2)
(2)
[10]
SECTION B: NOTES ON CONTENT
GENETICS AND HEREDITY
Genetics is the science of inheritance and studies the principles of heredity and
variation. The hereditary instruction carried within the DNA ensures that offspring
resemble their parents and ensures that genetic variation can take place, resulting
in survival of the fittest.
Genetics and sexual reproduction:
During sexual reproduction, offspring are produced that resemble the parents.
Remember that two haploid gametes are the result of the process of meiosis. The
gametes fuse during reproduction and the result is a diploid zygote, containing a
double set of chromosomes. One set of the chromosomes came from the male
gamete, which contains the DNA from the father. One set of chromosomes came
from the female gamete and contains the DNA from the mother. The child therefore
contains DNA from both parents.
© Gauteng Department of Education
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DEFINITIONS AND IMPORTANT TERMS AND CONCEPTS:
 Chromatin network: visible as thread-like structures in the nucleus of an inactive
cell
 Chromosome: consists of DNA (which makes up the genes) and protein.
 Gene: the heriditary unit of DNA that occupies a specific location on a
chromosome and controls the development of the characteristics
 Allele: one of two contrasting genes that determine alternative characteristics in
inheritance because they are situated in the same position or locus on
homologous chromosomes
 Locus: The exact position or location of a gene on a chromosome.
 Genotype: This is the total genetic composition of an organism. It is the
information present in the gene alleles, for example BB, Bb or bb.
 Phenotype: This is the external, physical appearance of an organism. The
phenotype is determined by the genotype. (Dominant traits will be displayed in
the offspring (BB or Bb). The recessive gene allele is not displayed when the
offspring is heterozygous for a trait. The recessive allele is always present and
can be transferred to offspring. A recessive trait is only displayed in the
phenotype, when both recessive gene alleles are present e.g.: bb)
 Dominant allele: an allele that masks or suppressed the expression of the allele
partner on the chromosome pair and the dominant characteristic is seen in the
homozygous (e.g: TT) and heterozygous state (e.g: Tt)
 Recessive allele: an allele that is suppressed (dominated) when the allele
partner is dominant. The recessive trait will only be expressed/seen if both alleles
for the trait are recessive e.g: tt
 Homozygous: when two alleles that control a single trait are alike for a
characteristic resulting in true-breeding for a particular characteristic
 Heterozygous: when two alleles on the same locus are different for a particular
characteristic. This will result in a hybrid.
 Gene mutation: a change of one or more bases in the nuclear DNA of an
organism. If the mutation is favourable, the organism survives but should the
mutation be unfavourable, the organism will die.
 Multiple alleles: when there are more than two possible alleles for one gene
locus.
 Complete dominance: one allele is dominant over the other allele, which is
recessive. The recessive trait will be masked in the homozygous dominant and
heterozygous offspring.
 Incomplete/partial dominance: No one allele is dominant over the other allele/s
and are thus not recessive or dominant. When combined, they produce a new
third phenotype e.g: black fur and white fur = grey fur
Examples:
Incomplete dominance in flowers:
Colour key: R (red)
W (white)
P1
Phenotype : red x white
Genotype:
RR x WW
Meiosis
Gametes
RR x W W
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Fertilisation
F1
Genotype: 4:4 RW
Phenotype: 100% pink
Incomplete dominance in humans:
Curly CC plus Straight SS = Wavy CS

Co-dominance: Both gene alleles are equally dominant so the heterozygous
individual expresses both traits, example: blood groups.
Protein A and protein B are coded by alleles A and B. If no protein A or B is
present, then these cells will be coded by the allele O. This means that there are
three possible alleles for this one gene locus in humans. When there are more
than two possible alleles, it is termed multiple alleles. Any two of these alleles
will occur in combination in an individual. The alleles A and B are co-dominant
and A and B completely dominate allele O. When two individuals with AB blood
type have children, the children can be type A, type B or type AB.
Phenotype/Bloo
d type
Genotype
Can receive blood from:
A
IA I A
A or O
A
A
I I
B
IB IB
B
B
I I
AB
I A IB
A, B, AB or O
(also known as the universal
acceptor because blood group
AB can accept blood from any
other group)
O
i i
O
(also known as the universal
donor because any blood group
can receive O blood)
B or O
Co-dominance in humans:
Homozygous dominant = IA IA (blood group A)
Homozygous recessive = IB IB (blood group B)
Heterozygous = IA IB (blood group AB)
Co-dominance in flowers:
Homozygous dominant = RR (red)
Homozygous dominant = WW (white)
Heterozygous = RW (white with red markings/red with white markings)
© Gauteng Department of Education
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

Monohybrid cross: when one pair of traits is crossed to determine the possible
inheritance in the offspring. There will always be 4 possible combinations.

Dihybrid cross: the crossing of two pairs of contrasting traits to determine the
possible inheritance of the offspring. The filial generation will result in 16 possible
combinations (4 x 4 possibilities = 16). Dihybrid crosses relate to Mendel’s law
of independent assortment.
Filial generation: The first generation of parents (P1) will produce offspring that
result from a cross called the first filial generation (F1) and shows the possible
inheritance of the offspring. When the offspring mature they will become the P2
(second parent generation) and produce offspring in the second filial generation
(F2).
EXAMPLES OF MONOHYBRID CROSSES:
There are basically FOUR types of crosses. If you know these crosses, you should
not have a problem. Learn them well.
We will use one general trait like hair colour:
B = brown hair colour (dominant trait)
b = blonde hair colour (recessive trait)
CROSS EXAMPLE 1: (Homozygous dominant x Homozygous recessive)
[OFTEN ASKED]
P1 (first parent generation)
Phenotype:
Brown x blonde
Genotype:
BB x bb
Meiosis
Gametes:
B B x b b
fertilization
B
B
b
Bb
Bb
b
Bb
Bb
F1 (first filial generation = first offspring)
Genotype:
Bb 4:4 heterozygous offspring
Phenotype:
100% brown
CROSS EXAMPLE 2: (Heterozygous x Heterozygous)
[OFTEN ASKED]
P1
Phenotype:
Brown x Brown
Genotype:
Bb x Bb
Meiosis
Gametes:
B b x B b
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fertilization
B
b
B
BB
Bb
b
Bb
bb
F1 Genotype: 1:4 BB homozygous offspring
2:4 Bb heterozygous offspring
1:4 bb homozygous
Phenotype: 75% brown and 25% blonde
CROSS EXAMPLE 3: (Homozygous dominant x Heterozygous)
P1
Phenotype:
Genotype:
Gametes:
Brown x Brown
BB x Bb
Meiosis
B B x B b
fertilization
B
B
B
BB
BB
b
Bb
Bb
F1 Genotype:
2:4 BB homozygous offspring
2:4 Bb heterozygous offspring
Phenotype: 100% brown
CROSS EXAMPLE 4: (Homozygous recessive x Heterozygous)
P1
Phenotype:
Genotype:
Blonde x Brown
bb
x Bb
Meiosis
Gametes:
b b x B b
fertilisation
b
b
B
Bb
Bb
b
bb
bb
F1
Genotype:
Phenotype:
2:4 Bb heterozygous offspring
2:4 bb homozygous offspring
50% brown and 50% blonde
© Gauteng Department of Education
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HOW TO TACKLE ANSWERING PEDIGREE DIAGRAM QUESTIONS
Generation
1
2
3
A
E
G
F
J
K
M
L
N
D
H
I
4
5
C
B
O
P
Female with blonde hair
Male with blonde
hair
Female with brown
hair
Male with brown
hair
Analysing the genetic lineage in a pedigree diagram:
Step 1:
Mark all the homozygous recessive individuals with blonde hair. This
will be all the white shapes: E, F, G, I, K, N and P as bb on the
pedigree chart.
Step 2:
Work from the generation line 5 up towards the generation line 1 so that
you start with the last offspring on the pedigree diagram. To produce
an offspring with bb, BOTH parents must have at least one
homozygous recessive gene (b). If the parent is a white shape – then
the parent is bb and already marked. If the parent is a shaded shape
and produced a bb offspring, then the parent must be heterozygous
Bb. Mark the Bb parents on the pedigree diagram.
Step 3:
Parents that are shaded shapes and produce only shaded shape
offspring, can be homozygous BB or heterozygous Bb. Look to the
next generation and then work backwards. Mark the parents on the
pedigree diagram.
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Step 4:
Answer the questions that relate to the pedigree diagram.
Try to work out the genotype of A, B, C, D, H, J, L, M and O on your own first.
Let us see if you were right:
o A and B are Bb because they produce G (bb)
o If C is BB then D must be Bb or C is Bb then D is BB because H must be Bb
to produce K (bb)
o J is Bb because G is bb and H is Bb (produced sister K - bb)
o L and M are both Bb because parent J is Bb and I is bb so they cannot be
homozygous BB AND L and M produce a son (N) and daughter (P) that are
both homozygous bb
o Offspring O can be either BB or Bb because both parents are heterozygous
Bb


Karyotype: this is the number and appearance of the chromosomes arranged in
homologous pairs, in the nucleus of an individual belonging to a specific species.
In humans, we have 46 chromosomes = 23 pairs (22 pairs are autosomes and 1
pairs are sex chromosomes). The karyotype is used to study chromosomal
aberrations, cellular functions, taxonomic relationships and to determine
evolutionary links and events.
Sex determination in humans: the somatic cells in humans are all diploid and
contain 23 pairs of chromosomes in each nucleus. There are 22 pairs of
autosomes and one pair of sex chromosomes (gonosomes) in the human
genome (genetic make-up). Females have identical XX sex chromosomes while
males have dissimilar XY sex chromosomes. The Y chromosome is smaller and
hook-shaped. During gametogenesis (the formation of sex cells), meiosis takes
place in the ovaries and testes. Each egg cell will contain an X chromosome. In
the male, half the sperm cells will have X and half will have Y chromosomes.
Each time fertilisation occurs, there is a 50% chance of the zygote being male
and a 50% chance of the zygote being female, X + X = XX and X + Y = XY.
P1 Phenotype:
Genotype:
Gametes:
male x female
XY x XX
Meiosis
X Y x X X
fertilization
X
X
X
XX
XX
Y
XY
XY
F1 Genotype:
Phenotype:

XX 2:4
XY 2:4
50% males
50% females
Sex-linked alleles are alleles related to the sex chromosomes of the individual.
Autosomal chromosomes have the same number of alleles in both homologous
chromosomes. With sex chromosomes there will be more genes on the X
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chromosome than on the Y chromosome because the Y chromosome is shorter.
Let’s look at haemophilia:
Haemophilia:
Haemophilia is a hereditary bleeding disorder caused by a sex-linked recessive
gene. The clotting factor deficiency, prevents the blood from forming a stable
fibrin clot. Blood seeps into the tissue and joints. Haemophilia can be the result of
two possible genes. Both haemophilia A and B are inherited as X-linked
recessive genes. One gene controls the production of the protein called factor
VIII and causes haemophilia A, which affects 85 per cent of haemophilia
sufferers. The other gene controls the production of the protein factor IX and
causes haemophilia B, which affects 15 per cent of the cases. Males carry one X
chromosome only. The Y chromosome carries no gene for blood clotting. This
means that the condition of haemophilia is seen in males with only one defective
gene present. A female with one defective gene will be a carrier because the
other X chromosome will carry the normal dominant gene.
For a normal male and female carrier (heterozygous) cross:
P1 Phenotype:
normal male x female carrier
Genotype:
XHY x XHXh
Meiosis
Gametes:
XH Y x XH Xh
fertilization
XH
Xh
XH
XH XH
XH Xh
Y
XH Y
X hY
1:4 XH XH
1:4 XH Xh
1:4 XH Y
1:4 Xh Y
Phenotype: 25% XH XH: female is clear and does not carry the trait.
25% XH Xh: female is a carrier.
25% XH Y: male is clear.
25% Xh Y: male is affected – has haemophilia.
F1 Genotype:
For an affected male and normal female cross:
P1
Phenotype:
affected male x normal female
Genotype:
Xh Y
x
XH XH
Meiosis
Gametes:
X h Y x X H XH
fertilization
XH
XH
Xh
XHXh
XHXh
Y
XHY
XHY
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2:4 XHXh (trait is carried on this X chromosome)
2:4 XHY
Phenotype: 50% female is a carrier
50% male is clear and normal
F1
Genotype:
The Principles of Heredity: (Make sure that you know Mendel’s laws)
 Mendel’s law of dominance and segregation
When two individuals with contrasting pure breed characteristics are crossed, the
individuals of the first generation (F1) will ALL resemble the parent possessing
the dominant characteristic.
P1
Phenotype:
Genotype:
Gametes:
Tall plants x short plants
TT x tt
Meiosis
T T x t t
fertilization
T
T
t
Tt
Tt
t
Tt
Tt
F1
Genotype:
4:4 Tt heterozygous offspring
Phenotype:
100% Tall
Note that the F1 offspring show characteristics from both parents but in the
phenotype, all are tall.
The plants of the F1 grow and mature (Tt). When they reproduce, half of the
gametes will contain the characteristic for tallness (T) and the other half, for
shortness (t). The characteristic for shortness is the recessive characteristic and
it will appear in the second cross offspring called the F2 generation.
P2
Phenotype:
Genotype:
Gametes:
Tall plants x tall plants
T t x T t
Meiosis
T t x T t
fertilization
T
t
T
TT
Tt
t
Tt
tt
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F2
Genotype: 1:4 homozygous Tall, 2:4 heterozygous Tall, 1:4
homozygous short (1 TT : 2 Tt : 1 tt)
Phenotype: 75% tall (1 homozygous tall + 2 heterozygous tall)
25% short (1 homozygous short)

Mendel’s law of independent assortment
Each characteristic is controlled by allele genes on a separate pair of
chromosomes. Mendel stated that the different pairs of chromosomes segregate
independently in a hybrid so each characteristic or trait is sorted out
independently of any other trait in the hybrid.
Mendle used peas with a genetic trait for a round seed versus a wrinkled seed
AND a yellow versus green colour of the seeds. Independent combinations for
the traits round and yellow, round and green, wrinkled and yellow or wrinkled and
green will result. (4 x 4 = 16 combinations)

DNA sequencing:
Scientists agree that individual organisms change to adapt to the environment. A
species is a group of organisms that are similar in appearance, share the same
DNA sequences, perform the same mating rituals and interbreed. It is the
sequence of bases in the DNA that is the code for that organism. The sequence
(order) of bases tells the cell what proteins to make. The sequence of bases
dictates the sequence of amino acids, which determines the shape of a protein.
The sequence of the DNA and the number of chromosomes, provides evidence
of relationships between groups of organisms. Similarly, the DNA sequencing of
all mammals further suggest phylogenic relationships.

Mutations (also refer to the note sets on DNA Sessions 1-4))
A gene mutation is a change in the genetic material/DNA sequencing in the cell.
A mutations that assist the organism to adapt to its environment, is favourable
and will become a fixed mutation, passed to the next generation. It will ensure
variation, natural selection and survival of the species by increasing the gene
pool. Lethal mutations are unfavourable and will result in death. A neutral
mutation has no immediate effect on the individual. It is passed on to the next
generation and when the environment changes, the mutation may assist the
organism to adapt and cope with the change.
Mutations occur when:
 a codon is substituted – a frameshift mutation results altering the gene
expression of the codons so a different amino acid is translated from the
original resulting in different proteins
 one or more nitrogenous bases are deleted from the codon or replaced – a
point mutation results (e.g.: sickle cell anaemia)
 additional nitrogenous bases are included into the DNA – a point mutation
results

Chromosomal aberrations/anomaly: when there is an incorrect number of
chromosomes or a structural abnormality in one or more chromosomes. This
occurs when there is an error in cell division (meiosis or mitosis). A
chromosomal aberration is an accident and not inherited, e.g.: when an
individual is missing a chromosome from a pair or has more than two
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chromosomes to a pair. A Down’s syndrome baby has three copies of
chromosome 21, rather than two so the chromosome's structure is altered like
when:
 a portion of the chromosome is missing or deleted
 a portion of the chromosome is duplicated so it will carry extra genetic
material
 a portion of one chromosome is transferred to another chromosome
 a portion of the chromosome has broken off and reattached so that the
genetic material is inverted.
Albinism as an example of a mutation:
Albinism is a rare inherited defect that results in a lack of the pigment melanin in
the skin, hair and eyes making them sensitive to sunlight and susceptible to skin
cancer. Albinism is caused by a single pair of recessive alleles and will only
show in the homozygous state. Heterozygous parents are carriers and stand a
25 per cent chance of producing a baby with albinism.
When one parent is affected and one is normal:
P1
Phenotype:
affected parent x normal parent
Genotype:
bb
x
BB
Meiosis
Gametes:
b b x B B
fertilization
F1
b
b
B
Bb
Bb
B
Bb
Bb
Genotype: 4:4 heterozygous Bb
Phenotype: 100% appear normal - offspring will be carriers as both
recessive genes are required for the trait to come through
in the genotype and phenotype.
When both parents are heterozygous carriers:
P1 Phenotype: normal heterozygous parent x normal heterozygous parent
Genotype:
Bb
x
Bb
Meiosis
Gametes:
B b x B b
fertilization
B
b
B
BB
Bb
b
Bb
bb
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F1

Genotype:
2:4 heterozygous Bb
1:4 homozygous BB
1:4 homozygous bb
Phenotype: 50% will be carriers
25% will be clear + 50% carriers = 75% will appear normal
25% will be affected
Genetic Engineering: the process where scientists alter, swap or manipulate the
genes on the DNA, to produce a different organism. Genetic engineering involves
the transfer of genes from one organism to an unrelated species.
Diabetics are people who cannot produce their own insulin. Insulin is a hormone
needed to regulate blood sugar. Biochemists have devised a way in which to produce
artificial insulin. A similar process is used to genetically modify many different
organisms. Make sure you know the basic process:









Bacteria produce restriction enzymes that ‘cut’ DNA molecules. These
restriction enzymes are extracted from the bacteria.
DNA is removed from a healthy person’s pancreas cells.
Restriction enzymes are used to ‘cut’ out a piece of DNA, which contains the
genes that produce insulin.
When the genes are transferred from one organism’s cells to another, the DNA in
the recipient cell is called recombinant DNA. Insulin is produced by using
recombinant DNA in the bacterium called Escherischia coli (E. coli), which lives in
the human gut.
Plasmids are taken out of a bacterium and cut open with the restriction enzyme.
The human genes are inserted into the plasmid. The healthy bacterium absorbs
the plasmids.
The piece of human DNA continues to produce proteins, which make insulin,
inside the bacterium.
The insulin is then extracted from the bacterium cell.
Diabetics inject themselves with this insulin everyday, so that they can regulate
their blood sugar.
Advantages of GM crops






Better nutritional value
Greater crop yield resulting in
higher food production and long
term reduction in costs
Crops are better adapted to less
favourable environments and
climates
Disease and pest resistant means
less insecticides and pesticides are
released into the environment
Increased biodiversity as new
varieties are developed
Efficient use of scarce agricultural
land as well as land that may
Disadvantages of GM crops






Possible increase in allergen and
carcinogen levels
Nutritional changes and possible
toxicity
Traits can be transferred to other
species like weeds
Cause un-natural selection pressure
Expensive start-up costs
DNA alteration of the new varieties
are owned and controlled by
biotechnology company which may
lead to issues with ethics and
ownership
© Gauteng Department of Education
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
previously not have been fit
Lack of transparency regarding
what is in our food
Cloning
With cloning, the nucleus of a somatic cell (2n) of one organism is removed. An
egg cell (n) is taken from an ovary. The nucleus of the egg cell is destroyed. The
somatic cell’s nucleus (2n) is then placed inside the egg cell. The egg cell is put
back into a uterus where it is allowed to grow and differentiate into an embryo.
When the baby is born, it is identical to the original organism. A sheep called
Dolly was cloned successfully in 1997.
Advantages of Cloning
Disadvantages of Cloning
Produce individuals with desired traits Objections to interfering with God’s creation
Better yields
Reducing the gene pool by reducing variation
Resistant to diseases
Cloned organisms may have developmental
problems
Organisms produced in a shorted
time
Costly process
Saving endangered species
Generate experimental waste
Produce body parts/organs for
transplant
May lead to killing clones for organs/body
parts
Produce offspring when organisms
are infertile
Cruelty to animals and inhumane behaviour
Stem Cell research:
A stem cell is a cell that has the potential to regenerate multiple cell type tissue
and self-renew so a stem cell is able to produce new cells over a long term by the
process of mitosis. Once mitosis occurs, the cells are able to differentiate into
many different types of specialized cells and tissue. Stem cells can be
harvested from umbilical cord blood (once a baby has been born), a foetal
blastocyst and bone marrow.
Stem cell therapy can be used to treat a variety of different human diseases:
 cancers like Leukemia
 degenerative diseases like Multiple Sclerosis
 diabetes mellitus where the pancreas no longer produces insulin
 muscle damage
 organ damage and
 certain genetic diseases in conjunction with gene therapy
© Gauteng Department of Education
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SECTION C:
HOMEWORK QUESTIONS
(Questions for homework taken from DoE Additional Exemplar 2008 Paper 1 and
Gauteng Prelim 2009 Paper 1)
QUESTION 1: 10 minutes
In mice, brown (B) coat colour is dominant over grey (b) coat colour. Show a cross
between a heterozygous parent with a brown coat colour and one with a grey coat
colour up to the F1 generation. Also give the phenotypes of the F1 generation.
(8)
QUESTION 2: 8 minutes
Learners want to investigate eye colour in fruit flies (Drosophila melanogaster). Fruit
flies can have red (R) eyes or white (r) eyes. Red eye colour is dominant and white
eye colour is recessive. Male fruit flies, homozygous for red eye colour, were bred
with female fruit flies, homozygous for white eye colour.
Show how the possible phenotypes and the genotypes of the F1 generation for eye
colour may be obtained.
(6)
QUESTION 3: 10 minutes
Haemophilia is a sex-linked hereditary disease that occurs as a result of a recessive
allele on the X-chromosome. Study the family tree below and answer the questions
that follow:
(Use the symbols H for normal and h for haemophilia above the sex chromosomes,
for example.: XHXh)
3.1.
3.2.
Write down the genotype of Stefan.
(2)
Peter and Susan would like to have a fourth child. Calculate the percentage
probability of this child having haemophilia.
(6)
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SECTION D:
SOLUTIONS FOR SECTION A
1.1
1.2
1.3
1.4
1.5
1.6
1.7
D
C
B
B
C
A
C
(7x2) (14)
2.1
2.2.
2.3.
2.4.
2.5.
2.6.
2.7.
2.8.
A
C
A
B
D
D
C
D
(8)
3.
P1
Phenotype:
Genotype:
Black x Brown
Bb x bb
Meiosis
Gametes:
B, b x b 
fertilisation
b
b
B
Bb
Bb
b
bb
bb
F1
Genotype: Bb and bb
Phenotype: Black and brown
1 mark for stating P1 AND F1 (must have both)
1 mark for stating meiosis AND fertilisation  (must have both) any 6 = (6)
4.1
4.2
5.1
5.2
5.3
(a) homozygous dominantand heterozygous (2)
(b) homozygous recessive (1)
Normal is dominant and the dominant condition can show up in either
homozygous or heterozygous state
OR
To have a normal child the person must have at least one dominant
gene/phenotype is normal (2)
Plant A - YY
Plant B - yy (2)
Yellow: green  = 3 : 1 (2)
Phenotype – green peas 
Genotype – yy(2)
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6. 1.
Mr. Xhosa - IAIB 
Wife - IBIB or IBi 
F1 is IAIB or IBIB or IBi or IAi. 
Baby ‘A’ is the only possible blood group . Baby ‘O’ is not a possibility
(Remember that in blood groups there are three alleles A, B and O. A
and B are co-dominant over O which is recessive. There must be two of
the same alleles if a recessive trait is present in the individual)
6.2.
Mr. Mbundwini - IAIA or IAi 
Wife – Not given, but assume she is recessive  . Therefore baby ‘O’ is the
possible blood group  as ‘O’ cannot be the result of Mr. Xhosa and his
wife . (Each tick = ½ mark)
(6)
7. 1.
P1 ( for P1 and F1 – if both are present then half mark each)
Phenotype:
normal father x carrier mother  {***mother is heterozygous}
Genotype:
XHY x XHXh 
Meiosis ( for meiosis and fertilization – half mark each)
Gametes: XH Y x XH Xh 
fertilization
XH
Xh
XH
XH XH
XH Xh
Y
XH Y
X hY
F1
XH XH
XH Xh
XH Y
Xh Y (all 4 genotypes: )
Genotype:
1:4
1:4
1:4
1:4
Phenotype:
50% normal daughters (XH XH and XH Xh)
25% normal son (XH Y)
25% son with haemophilia (Xh Y) (all phenotypes correct = )
Max (6)
7.2.
25% chance /1 out of 4/ ¼ 
7.3.
The male has only one X chromosome Y chromosome does not have the
allele for this trait 
OR
If he had ‘h’ he would be a sufferer, therefore he must have had ‘H’.
Max
(2)
(2)
© Gauteng Department of Education
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SESSION NO: 6
TOPIC 1:
GENETICS AND INHERITANCE Part 2
TOPIC 2:
RESPONDING TO THE ENVIRONMENT - HUMANS: NERVOUS
SYSTEM Part 1
Teacher note:
Topic 1: Mutation, natural selection and genetic engineering: tell learners to read
about genetic engineering so that they form an opinion of whether this is good or
bad, but also so that they understand the basic process and the benefits to human
being. See notes on content in session 5.
Topic 2: Make sure that learners know and understand the nervous system and all
its components, the different types of nerves and also the reflex arc
1.
2.
3.
4.
Introduce session – 5 minutes (and go over basic idea as per the above
introduction)
Typical exam questions and solutions – 50 minutes
(Questions that are not completed must please be included with Homework)
Notes on Content – 15 minutes
Answer/memo discussion – 20 minutes
SECTION A: TYPICAL EXAM QUESTIONS
TOPIC 1:
QUESTION 1:
12 minutes
(Taken from DoE Feb/March 2009)
Read the following passage and answer the questions that follow.
GENETICALLY MODIFIED PIG BRED WITH 'GOOD FAT'
Scientists in the United States of America have produced genetically modified pigs
with fat containing omega-3 fatty acids. These fatty acids, which are usually found in
salmon, mackerel and fresh tuna, are thought to be responsible for a number of
benefits, from combating heart disease to improving intelligence.
Researchers from the University of Pittsburgh – School of Medicine created piglets
capable of converting less useful omega-6 fatty acids into omega-3 fatty acids. They
implanted 1 800 embryos into 14 female pigs. Ten live offspring, which were able to
make high levels of omega-3 fatty acids, were born.
[Adapted from: Cape Argus, 27 March 2006]
(Read the passage through and underline what you think will be the important
facts. Read the passage again, now answer the questions.)
1.1.
1.2.
1.3.
Name TWO health benefits of omega-3 fatty acids.
(2)
What percentage success did the scientists have with the implanted embryos
in forming a clone of pigs capable of producing omega-3 fatty acids? Show
ALL working.
(3)
(Show each step of the calculation.)
To produce genetically modified pigs, the gene that produces omega-3 fatty
acids is inserted into the pig embryos. Describe the steps in forming and
© Gauteng Department of Education
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1.4.
introducing many copies of the desirable gene (using bacteria) into the pig
embryos.
(4)
Give TWO reasons why:
a) Some people may support the use of genetically modified pigs to produce
omega-3 fatty acids.
(2)
b) Some people may be against the use of genetically modified pigs to
produce omega-3 fatty acids.
(2)
[13]
QUESTION 2:
12 minutes
(Taken from DoE November 2008 Paper 1)
The diagram below shows the steps of an experiment in which a large number of
genetically identical frogs were developed from unfertilised frog eggs. The nucleus of
each unfertilised egg was destroyed and replaced by a nucleus obtained from a body
cell from frog X.
(Reminder: refer to the notes on cloning)
2.1.
2.2.
The diploid number of chromosomes in the above frogs is 26. How many
chromosomes are present in the nucleus of the following cells?
(a)
Cell A
(1)
(b)
Cell B
(1)
Why can an egg containing a nucleus from the body cell of a frog develop
© Gauteng Department of Education
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2.3.
2.4.
2.5.
into a tadpole?
Explain why all the frogs produced from the treated eggs are genetically
identical.
Name the method of producing genetically identical offspring as shown in
the diagram.
State ONE reason why some people might:
(a)
Favour the process shown in the diagram
(b)
Be against the process shown in the diagram
(2)
(2)
(1)
(2)
(2)
[11]
QUESTION 3: 10 Minutes
(Own source)
A homozygous black rabbit with brown eyes is mated with a homozygous white rabbit
with blue eyes. Black fur colour is dominant over white fur and brown eyes is
dominant over blue eyes.
Show the genetic cross and indicate the genotypes of the F1 generation.
(8)
(Hint: Let B = Black fur, b = white fur, G = brown eyes and g = blue eyes.
Homozygous black with homozygous brown eyes = BBGG and homozygous
white with homozygous blue eyes = bbgg)
TOPIC 2:
QUESTION 4:
3 Minutes
(Taken from various DoE HG Paper 2 exams)
(Hint: Please do not to waste time when you answer Multi Choice questions.
Read the question, underlining the operative words, while covering the
answers. Then think of the correct answer. Uncover the answer options and
check if your answer is there. If it is, then tick next to the letter. If it is not, reread the question and try to see exactly what is being asked. Then review the
answer options again to find the correct answer. Always answer Section A last
with the Multi-choice questions answered right at the end of the exam paper as
you can waste a lot of time on them.]
Various possible options are provided as answers to the following questions. Choose
the correct answer and write only the letter (A – D) next to the question number.
4.1
Which of the following structures will enable a dancer to carry out dance
movements?
1.
Cerebellum
2.
Proprioceptors
3.
Hypothalamus
4.
Cerebral cortex
A
1 only
B
1 and 2
C
1, 2 and 3
D
1, 2, and 4
4.2
Which of the following parts of the brain regulates appetite?
A
Medulla oblongata
B
Cerebellum
C
Hypothalamus
D
Cerebrum
© Gauteng Department of Education
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4.3
The autonomic nervous system controls …
A
the skeletal muscles.
B
the senses.
C
the contraction of involuntary muscles.
D
reflexes.
(Questions 4.4 to 4.8 Taken from DoE Exemplar 2011 Paper 2 )
The diagram below shows the human brain (longitudinal section), spinal cord
(transverse section) and the right leg.
Four options are provided as possible answers to the following questions. Choose
the answer and write only the letter (A–D) next to the question number.
4.4
Which part of the brain is indicated by 1?
A
Cerebrum
B
Medulla
C
Cerebellum
D
Hypothalamus
4.5
Which ONE of the following is a function of the part of the brain numbered 2?
A
Perception of sensations
B
Centre for control of breathing
C
Maintenance of equilibrium and balance
D
Centre for regulation of body temperature
4.6
Under normal circumstances, which numbered part coordinates the
movements of the legs?
A
2
B
3
C
4
D
5
4.7
Which ONE of the following comparisons between 3 and 4 is FALSE?
A
3 is a sensory neuron, while 4 is a motor neuron.
© Gauteng Department of Education
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B
C
D
4.8
3 leads from the receptor, while 4 leads to the effector.
3 enters the dorsal root, while 4 leaves through the ventral root.
The cell body of 3 is located in the spinal cord, while that of 4 is
found outside the spinal cord.
Which ONE of the following is FALSE about the role of the brain and spinal
cord involved in the action in the diagram?
A
The brain is aware of the tap on the knee with the hammer.
B
An effector is stimulated to bring about a response.
C
The spinal cord receives sensory impulses from the knee.
D
The brain receives sensory impulses from the spinal cord and sends
motor impulses to the leg muscles.
(8 x 2) [16]
QUESTION 5:
3 Minutes
Letters X and Y represent neurons that conduct impulses to and from the brain via the
spinal cord. Study the diagram and answer the questions that follow.
Using the given key, write down the correct letter (A, B or C in key) of the condition
that explains each of the following:
[Remember: damage to X will mean that sensory neurons will not be able to
send impulses to the CNS. Damage to Y will mean that the motor neurons will
not be able to stimulate muscles to move.]
© Gauteng Department of Education
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5.1
5.2
5.3
When the skin of the toe is stimulated, the toe moves and the person knows
that it is moving.
(1)
The person can move the toe, but cannot feel the movement.
(1)
The person can feel a pin pricking the toe, but cannot move the toe.
(1)
[3]
QUESTION 6:
6 Minutes
(Taken from DoE Feb/March 2012 Paper 2)
Study the following diagram showing a reflex arc.
6.1.
6.2.
6.3.
6.4.
Identify the neuron labelled A.
Name the type of neuron that is connected to structure B.
Explain the effect on the body if the neuron mentioned in QUESTION 6.2
is damaged.
Explain the significance of reflex actions in humans.
(1)
(1)
(3)
(2)
QUESTION 7: 10 Minutes
(Modified from DoE Nov 2012 P2)
Study the diagram representing the structure of the human brain below.
© Gauteng Department of Education
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7.1.
7.2.
7.3.
Identify the parts labelled:
a) C
b) E
Write down the letter (A to F) of the part which:
a) controls body temperature
b) controls heart beat and breathing rate
c) perception of senses, higher intelligence, memory
d) controls balance, equilibrium and muscle tone
e) point of the reflect arc
Explain how the brain is protected.
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(5)
[12]
SECTION B: NOTES ON CONTENT
TOPIC 1: Refer to session 5 notes on content.
TOPIC 2: RESPONDING TO THE ENVIRONMENT - HUMANS: NERVOUS
SYSTEM
Terminology & definitions:
Homeostasis: processes to maintain a stable, balanced internal environment within
the body involving co-ordination between the nervous system and the endocrine
system.
Central Nervous System: is made up of the brain and the spinal cord
Peripheral Nervous System: receives internal and external stimuli, converts the
stimuli into impulses and sends impulses to the central nervous system.
Autonomic Nervous system: is made up of the sympathetic and parasympathetic
nervous systems that regulate homeostasis. Both systems function antagonistically.
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The sympathetic nervous system stimulates organs and the parasympathetic
nervous system inhibits the same organs.
Double innervation: Each organ in the body is supplied with nerves from both the
sympathetic and parasympathetic nervous systems.
Neuron: a single nerve cell.
Nerve: is made up of millions of neurons
Neurotransmitters: this is a chemical substance secreted by synaptic vesicles in
the presynaptic neuron, to assists in transmitting an impulse across the synaptic gap.
Meninges: membranes that surround the brain. There are three meninges namely:
the duramater, the arachnoid and the piamater.
Reflex arc: This is the path travelled by the nerve impulse from the receptor to the
effector, through the spinal cord.
Reflex action: a rapid automatic response as a result of a stimulus received by a
receptor, converted to an impulse that passes through the spinal cord reflex arc to a
receptor.
The Nervous System: controls the functioning of all the systems in the body. It
allows humans to react to internal and external stimuli. The nervous system controls
and co-ordinates every movement and all organs, glands and blood vessels in
response to information received.
The nervous system can be divided into three systems, which together coordinate
the functioning of the body:
 Central nervous system – brain and spinal cord
 Peripheral nervous system – sensory, motor and mixed nerves
 Autonomic nervous system – sympathetic and parasympathetic
Nervous tissue: Animals have a complex system of nervous tissue called neurons
or nerve cells to send information to the central nervous system. Nervous tissue is
adapted to carry and react to all stimuli. A nerve is composed of nerve fibres that
are held together by connective tissue. One nerve consists of millions of neurons.
Receptors receive the stimulus and convert it to an impulse. The impulse travels
along the neurons in milliseconds.
The types of neurons are:



Sensory neurons: They are unipolar (one pole) and bipolar (two poles).
Sensory neurons always conduct impulses from the receptor to the CNS (spinal
cord and brain).
Motor neurons: They are multipolar neurons with many dendrites. Multipolar
neurons always carry impulses away from the CNS (spinal cord and brain).
Connector / inter-neurons: They are multipolar and connect sensory neurons
to motor neurons in the spinal cord and the brain.
Make sure you can identify and state the function of each of the following
sensory and motor neuron structures:
 nucleus – controls all the cell’s functions
 cell body – consists of cytoplasm with a nucleus
© Gauteng Department of Education
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



cytoplasm – contains very fine neurofibrils that extend into the axon and
dendrites. Also contains Nissl bodies that contain rRNA responsible for the
synthesis of proteins
myelin sheath – covers and protects the axon (provides electrical insulation).
May also be responsible for repairing damage to the axon.
axon – conducts impulses away from the cell body
dendrites – receive impulses and conduct them to the cell body
Transmission of nerve impulses: the synapse is the point where an impulse
passes from the terminal branch of one neuron to the dendrite of the next neuron.
The neurons do not touch each other. The gap between the two neurons is called
the synaptic gap. Neurotransmitters carry the impulse across the synaptic gap.
Once they reach the opposite side, enzymes destroy the neurotransmitters to prevent
the impulse from being carried backwards. The impulse can only ever travel in one
direction.
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[Only learn the position of the following structures: nucleus, cell body,
cytoplasm, myelin sheath, axon, dendrites)
The Central Nervous System:
Brain: protected by the bones of the cranium and the spinal cord is protected by the
bones of the vertebrae and surrounded by three layers of membranes called
meninges for protection. The cortex consists of cell bodies and is called the grey
matter. The medulla consists of the nerve fibre axons and is called the white matter.
The brain is divided into two hemispheres (left and right). The corpus callosum
connects the left and right side of brain allowing the two hemispheres to
communicate and coordinate activities.
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Make sure that you know the location and function of the following (see
diagram – functions are included):
 cerebrum
 cerebellum
 corpus callosum
 medulla oblongata
 spinal cord
The Spinal Cord: protected by the vertebrae, the 3 meninges with the
cerebrospinal fluid. The spinal cord is the pathway for all the impulses that are
conducted to and from the brain and also processes reflex actions. Sympathetic and
parasympathetic nerve impulses are conducted along the spinal cord to all organs.
The reflex arc: a reflex arc is the path travelled by the nerve impulses. It is a rapid
automatic response to a stimulus that is received by a sensory organ to ensure a
quick response. The reflex arc will cause a reflex action, allowing the body to
respond very quickly to protect itself against severe injury.
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The mechanism of a simple reflex arc is as follows:
 The finger is pricked by a pin.
 Sensory receptors in the skin of the finger receive the stimulus.
 The physical stimulus is transformed into a nerve impulse.
 The sensory neuron conducts the impulse to the spinal cord.
 The impulse enters the dorsal root of the spinal cord.
 It passes into the cell body of the sensory neuron situated in the dorsal root
ganglion.
 The impulse moves along the axon into the dorsal horn of the grey matter.
 The impulse is transmitted over the synaptic connection to the dendrite of the
connector neuron.
 The impulse travels along the axon of the connector neuron.
 The impulse is transmitted over the synaptic connection to the dendrites of the
motor neuron cell body.
 The impulse is carried away from the cord by the axon of the motor neuron.
 The impulse exits the cord through the ventral root.
 The terminal end branch of the motor neuron ends in the muscles of the forearm.
 The impulse causes these muscles to contract and pull the hand away from the
painful stimulus of the pin prick.
Effects of drugs on the central nervous system: drugs that are legally prescribed
by a doctor and are used according to instructions are acceptable to treat illness and
alleviate pain in patients. When drugs are used to enhance performance or as a
© Gauteng Department of Education
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psychoactive for non-therapeutic and non-medical effects, it becomes a problem.
Substances that are addictive and harmful are alcohol, amphetamines, barbiturates,
cocaine and opium alkaloids. It is a criminal offence to abuse any of these
substances.
Common drugs and how they affect the nervous system:
 Dagga: Drug that leads to hallucinations. Prevents long term memory and
decreases short term memory and problem solving abilities. Affects the parts of
the brain responsible for memory, emotions and decision making.
 Heroin: Causes lethargy (tiredness and listlessness), loss of self-control, and
leads to mental and physical deteriation. There is a serious danger of overdose,
leading to coma and death.
 Ecstasy: A synthetic drug with hallucinogenic properties and classified as a
stimulant. Ecstasy tablets produce an intensely enhanced sense of selfconfidence and energy and users experience a desire to touch others.
 Tik /Crystal Meth: Extremely addictive man-made stimulant and use can lead to
severe physiological and psychological dependence.
The Autonomic Nervous System: functions involuntarily and automatically and
is NOT controlled by the will. It maintains homeostasis by controlling vital activities.
It consists of nerves that are connected to the hypothalamus of the central nervous
system. The autonomic nervous system is subdivided into the sympathetic and
parasympathetic nervous systems that function antagonistically.
 The sympathetic nerves stimulate organs to prepare the body for action.
 The parasympathetic nerves slow the systems down and bring the body
back to a state of rest.
Each organ in the body is supplied with nerves from both systems and is termed
double innervation. The organs are stimulated (sympathetic) or inhibited
(parasympathetic) by the autonomic nervous system.
Functions regulated automatically by the autonomic nervous system include:
 the heartbeat and breathing rate (through the medulla oblongata)
 digestion and peristalsis
 pupil size
 bladder size
 sweat glands
 liver function
 amount of blood in the arteries.
Peripheral nervous system: is made up of sensory cells called receptors that
respond to stimuli. When the receptors are stimulated, they convert the stimulus into
a nerve impulse. This nerve impulse is transmitted along sensory neurons to the
central nervous system. There are 12 pairs of cranial nerves and 31 pairs of spinal
nerves that enter from the body and form art of the peripheral nervous system.
Examples of receptors:
 Photoreceptors are sensitive to light stimuli, for example the eye.
 Chemoreceptors are sensitive to chemicals as a solution or gas, for
example the tongue and nose.
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

Mechanoreceptors are sensitive to changes in pressure such as touch,
sound and gravitational stimuli, for example the ear, skin, muscles and
tendons.
Proprioceptors: They respond to gravitational pull to maintain balance and
equilibrium of muscles and tendons.
Diseases and disorders of the nervous system:
Alzheimer’s disease: the frontal and temporal lobes of the cerebral cortex are
affected so the conscious part of the brain that produces memory is slowly destroyed.
The cells that produce acetylcholine begin to deteriorate. Acetylcholine is a
neurotransmitter that is involved with memory formation. The neuron function
decreases and the neurons die, the brain shrinks because there is a loss of the nerve
cells. It has been found that Alzheimer’s is passed on genetically and therefore runs
in families. During the primary stages of this disease, patients become very forgetful,
as the short-term memory is affected. In advanced stages, the patient may not even
recognise close family members. Patients lose the ability to speak, read, walk and
control their bladder and bowel movement. This is a very stressful disease as
patients feel their minds slipping away and become very confused.
Multiple sclerosis
Multiple (many) sclerosis (scarring) is a degenerative disease resulting when the
myelin sheath surrounding the neuron axons in the white matter of the brain and
spinal cord are attacked and damaged by the body’s own immune system. The
neurons loose the ability to conduct impulses and communicate effectively once
demyelination occurs. Multiple sclerosis may be caused by a combination of a
number of factors like genetics, environment and infectious diseases. Genetic
variations of specific genes have been linked to an increased risk of developing the
disease. Environmental factors like high stress levels, lack of vitamin D (reduced
sunlight), various toxins and solvents, smoking and poor diet may contribute to the
risk of developing multiple sclerosis. Infectious diseases that affect the brain and
cerebrospinal fluid may cause demyelination of the neurons like encephalomyelitis.
Other viral diseases that have shown to impact the onset of multiple sclerosis are
human herpes viruses, measles, mumps and rubella.
Symptoms would include sensations like tingling, numbness in limbs, loss of coordination, weakness and chronic pain in muscles and various cognitive problems
like depression. There is no known cure for multiple sclerosis. Various treatments
and medication is used to treat the symptoms to improve quality of life.
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SECTION C:
HOMEWORK QUESTIONS
TOPIC 1:
QUESTION 1: 10 minutes (Taken from DoE Additional Exemplar 2008 Paper 1)
Study the diagram below that shows the cloning of a sheep named Dolly.
1.1.
1.2.
1.3.
1.4.
1.5.
Why was it necessary to remove the nucleus from the egg cell of the second
donor before the sheep could be cloned?
(2)
Would Dolly have any characteristics of the second donor sheep?
(1)
Explain your answer to QUESTION 1.2.
(2)
Number 5 on the diagram states that 'the embryo is cultured'. Through which
process of cell division does the embryo develop?
(1)
Describe TWO reasons why people could be against genetic engineering. (4)
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TOPIC 2:
QUESTION 2: 12 Minutes (Modified from DoE Nov 2011 Paper 2)
Study the diagram below and answer the questions that follow.
2.1.
2.2.
2.3.
Write down only the letter (A–D) of the part which:
a)
Controls heartbeat
b)
Contains the centres that control balance, muscle tone and
equilibrium
c)
Has centres that interpret what you see
d)
Coordinates voluntary muscle movements
e)
Has grey matter on the inside and white matter on the outside
Name one function of the corpus callosum.
Explain the difference between a sensory neuron and a motor neuron.
SECTION D:
1.1
1.2
1.3
SOLUTIONS FOR SECTION A
- Combating heart diseases - Improving intelligence
(2)
(Mark first TWO only)
10  x 100  1 800
= 0,55 %
(3)
The gene responsible for producing omega-3 fatty acids is located 
in the DNA of salmon/fresh mackerel/tuna
© Gauteng Department of Education
(1)
(1)
(1)
(1)
(1)
(2)
(5)
40
1.4
2.1
2.2
2.3
2.4
2.5
This gene is cut  from the donor organism, inserted into a plasmid of a
bacterium
Bacteria replicates to form many copies of the gene 
These genes are then inserted into the cells of the zygote /embryo any (4)
(a) Support - Healthier for humans to eat /combating heart disease
- Mass production of healthy fat 
- Improves intelligenceany
(2)
(Mark first TWO only)
(b) Against - Cultural objection to eat meat from pigs
- The success rate is very low  - Expensive procedure 
- No value for vegetarians 
- Objection to eating any genetically modified food  any (2)
(Mark first TWO only)
(a) 13 
(1)
(b) 26 
(1)
Has a full set of chromosomes  /Diploid number of chromosomes/
complete set of chromosomes
(2)
They have same/identical chromosomes /genetic material / DNA from the
nucleus of the somatic/body cell collected from the same frog/X  (2)
Cloning  (1)
(a) In favour:
- Producing individuals with desired traits
- Better yield 
- Resistant to diseases 
- Organisms produced in a shorter time 
- Saving endangered species 
- Producing body parts 
- Produce offspring for organisms that cannot have offspring (1 x 2) (2)
(Mark FIRST answer only in learner’s script)
(b)Against:
- Objection to interfering with God’s /Supreme Being’s creation/nature
- Reducing the gene pool by reducing variation/ Reduces genetic diversity
- Cloned organisms may have developmental/morphological problems
- Costly process 
- May generate more experimental waste 
- May lead to killing of clones to obtain spare body parts 
- Cruelty to animals (1 x 2) (2)
(Mark FIRST answer only in learner’s script)
3.
P1 ( for P1 and F1 – if both are present then half mark each)
Phenotype:
Genotype:
black + brown eyes  x white +blue eyes
BB
GG  crossed with bb
gg
Gametes:
Meiosis( for meiosis and fertilization – half mark
each)
B G x b g 
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bg
bg
bg
bg
F1
BG
BbGg
BbGg
BbGg
BbGg
fertilization
BG
BbGg
BbGg
BbGg
BbGg
BG
BbGg
BbGg
BbGg
BbGg
BG
BbGg
BbGg
BbGg
BbGg
Genotype: 16:16  BbGg heterozygous offspring 
Phenotype: 100%  black with brown eyes
Max
(8)
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
D
C
C
A
B
D
D
D
(8 x 2) (18)
5.1.
5.2.
5.3.
C
A
B
(1)
(1)
(1)
6.1.
6.2.
6.3.
Interneuron/connector neuron/association neuron (1)
Motor neuron 
(1)
The person will become aware of the stimulus but the motor
neuron will not be able to transmit the impulse from the
interneuron to the effector organ /
muscles and movement will not take place/ reaction will not occur
(Max 3)
Helps to protect the body  by reacting quickly 
The interneuron makes a short cut  /not going to the brain/
uses a reflex pathway that is immediately available (Max 2)
6.4.
7.1.
7.2.
7.3.
C = cerebellum  (1)
E = medulla oblongata  (1)
a) hypothalamus
b) medulla oblongata 
c) cerebrum 
d) cerebellum 
e) spinal cord 
(5)
protected by the bones of the cranium 
three layers of membranes called meninges namely: duramater,
arachnoid and piamater
(5)
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SESSION NO: 7
TOPIC:
RESPONDING TO THE ENVIRONMENT - HUMANS: NERVOUS
SYSTEM PART 2
Teacher Note: ensure that learners know structure versus function of the human
eye, formation of the image, binocular vision, accommodation of the eye, pupillary
reflex mechanisms , short and long sightedness, astigmatism and cataracts. Ensure
that they know structure versus function of the human ear, hearing and balance,
middle ear infections, deafness and the treatment thereof.
1.
2.
3.
4.
Introduce session – 5 minutes (and go over basic idea as per the above
introduction)
Typical exam questions and solutions – 50 minutes
(Questions that are not completed must please be included with Homework)
Notes on Content – 15 minutes
Answer/memo discussion – 20 minutes
SECTION A: TYPICAL EXAM QUESTIONS
QUESTION 1:
15 minutes
(Taken from Study and Master Grade 12 Biology)
(Note: When answering multi-choice questions:
1. Read the question while covering the answers.
2. Think of the correct answer.
3. Look for your answer.
4. Write the letter down on your answer sheet.
BUT: If you do not know the answer after point 1 and 2, then:
3. Look at the options.
4. Try to think of why an option is wrong for the question and cross it out. If
there is an option that you don’t know, write a ? next to this option.
5. If you still do not know the answer, then select the ? option)
Various possible options are provided as answers to the following questions. Choose
the correct answer and write only the letter (A – D) next to the question number.
1.1. The tough, non-elastic tissue covering the outer portion of the eyeball is the:
A
choroid
B
sclera
C
conjunctiva
D
iris
1.2.
The shape of the lens in the human eye may be altered by the contraction or
relaxing of the:
A
optic nerve
B
muscles of the iris
C
muscles of the ciliary body
D
pupil
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1.3.
The sensation of sight in human beings originates in the :
A
yellow spot
B
optic nerve
C
cerebrum
D
retina
1.4.
The yellow spot of the human eye:
A
cone cells only
B
more cone than rod cells
C
cone and rod cells in equal number
D
rod cells only
1.5.
The following are part of the human eye:
1 cornea
2 lens
3 retina
4 iris
Which parts are respectively concerned with/in:
 Adjusting the focus?
 Preventing internal reflection?
 Recording changes in light intensity?
A
B
C
D
1.6.
5 choroid
2, 4 and 3
3, 4 and 1
2, 5 and 4
4, 1 and 5
When the tension of the suspensory ligaments in the human eye is slackened,
the….
A
lens becomes less convex
B
eye is focused for distant vision
C
pupil enlarges
D
lens bulges
QUESTIONS 1.7 to 1.9 refer to the diagram of the human eye.
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1.7.
The parts that control the amount of light rays that enter the eye are…..
A
1 and 2
B
1 and 3
C
2 and 3
D
3 and 4
1.8.
The greatest convergence takes place when light rays pass through the part
numbered…..
A
4
B
5
C
6
D
11
1.9.
The function of part numbered 9 is to:
1.
reflect light
2.
change the shape of the eyeball
3.
refract light rays
4.
prevent reflection
5.
supply the retina with nutrients and oxygen
6.
absorb excess light
Choose from the options numbered 1 to 6 to provide the functions of part
numbered 9:
A
1, 2, 3
B
4, 5, 6
C
2, 4, 6
D
1, 3, 5
1.10. When the tension of the suspensory ligaments in the human eye increases,
the…
A
lens becomes more convex
B
eye is focused for distant vision
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C
D
pupil opens wide
lens bulges
1.11. When the pupil of the human eye constricts, the receptors and effectors are
respectively the….
A
fovea centralis and ciliary muscle
B
pupil and ciliary muscle
C
pupil and radial muscles of the iris
D
fovea centralis and the circular muscles of the iris
1.12. In accommodation of the human eye, the….
A
pupil enlarges
B
ciliary muscles are involved
C
suspensory ligaments are always in a state of tension
D
circular muscles of the iris contract
1.13. Images of objects less than 6m from the eye are clearly focussed onto the
retina, when the….
A
ciliary muscles contract
B
pupil widens
C
muscles of the iris contract
D
curvature of the lens decreases
1.14. The optical disc where the fibres of the optic nerve leaves the eyeball, is
the….
A
yellow spot
B
iris
C
blind spot
D
retina
1.15. Which of the following occurs when you look up from reading a book to look at
a distant mountain on a clear, sunny day? The….
A
radial muscles of the iris contract
B
the pupil becomes more dilated
C
the ciliary muscles contract
D
the lens becomes thicker and rounder
(15 x 1 ) (15)
QUESTION 2:
4 minutes
(Taken from DoE May/June 2008 Paper 2)
Explain why, when a person enters a dimly lit room after being in bright sunlight,
objects become visible only after a while.
(4)
QUESTION 3:
18 minutes
(Taken from Bios best 2008 Grade 12 Biology)
The diagram below that represents a section through part of the human eye.
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3.1.
3.2.
3.3.
3.4.
3.5.
3.6.
Supply labels for the parts numbered 1, 3 and 5.
(3)
Supply the number and name the part that controls the amount of light that
enters the eye.
(2)
Mention the changes that the part names in Question 3.2 will undergo when
exposed to bright light.
(4)
List one function for each of parts 4 and 7.
(2)
Supply the number and the name of the part that is responsible for the
accommodation of the eye.
(2)
Explain the changes that will take place when the part named in Question 3.5
views an object closer that 6m.
(5)
QUESTION 4:
18 minutes
(Taken from DoE May/June 2008 Paper 2)
Study the following diagram of the human ear and answer the questions that follow.
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4.1
4.2
4.3
4.4
4.5
4.6
Identify parts B and G.
(2)
State the function of each of parts C and E.
(2)
Explain:
a) Why you can often clear a buzzing/humming in the ear by swallowing (3)
b) Why the membrane labelled F is much larger than membrane C
(2)
A dog has lost part A in an accident. Part A is replaced with a stiff, non-elastic,
solid plastic structure.
a) Is the plastic structure as effective as the original ear of the dog?
(1)
b) Explain your answer to QUESTION 4.4 (a).
(2)
Explain how part D and the retina of the eye function in similar ways.
(4)
Give ONE reason for part D being spirally shaped.
(2)
SECTION B: NOTES ON CONTENT
Terminology & definitions:
Photoreceptors: Specialized receptors to receive the stimulus of light and convert it
to an impulse. Photoreceptors in the retina of the eye are called rod and cone cells.
Refraction: To bend light – refraction takes place when light passes through a lens
that is bent by a convex [ ( ) ] shape or a concave [) ( ] shape
Stereoscopic vision: Also known as binocular vision - to see with two eyes, where
each eye will produce a slightly different image of the same object and allows us to
judge distance, depth and size of an object.
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Accommodation: The ability to change the focal length of the object by changing
the convex shape of the lens to assist with focussing on a near or distant object.
Myopia: Short-sightedness caused by a cornea that is too rounded so the image
falls short of the retina.
Hypermetropia: Long-sightedness caused by a lens that cannot become rounded
enough to refract light so the image falls behind the retina.
Mechanoreceptors: The Organs of Corti are receptors located in the cochlea of the
ear, which are stimulated by sound waves and convert the sound waves into
impulses.
Ossicles: Three little bones called the hammer, anvil and stirrup located in the
middle ear and that function to amplify sound.
Otis media: inflammation and infection of the middle ear which causes pressure on
the eardrum.
The Human Eye
The eyes are organs that make it possible for us to see.
Path of Light:
 Light rays pass from an object to the eye, through the transparent convex
cornea, aqueous humour, the biconvex lens and vitreous humour.
 As the light rays pass through the curved surfaces of the cornea and the lens,
light is refracted (bent).
 The lens refracts the light rays and forms an inverted (upside-down) image on
the retina, bringing the image into focus by making fine adjustments.
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


The rod and cone cells (photoreceptors) are stimulated by the light rays and
convert the stimulus into impulses.
These impulses are transmitted along the optic nerve across the optic chiasma
(cross-over) so that impulses enter the lower visual centres on opposite sides of
the mid-brain at the occipital lobes.
The upright images are interpreted for size, shape and colour of the object that
was seen.
Accommodation:
Binocular vision means to see with TWO eyes (bi = two). We are able to focus on
one object with both eyes increasing the field of vision. A sharp image falls on each
retina. The image from the left eye is always slightly different to the image from the
right eye. The two images join in the brain (occipital lobes) and results in
stereoscopic vision, which allows us to judge distance, depth and size of
objects.
The eyes can change the convex curve of the lens and therefore the focal length.
This process is termed accommodation.
Near vision (round lens) - When viewing an object at a distance of less than 6
metres:
 The ciliary muscles contract, causing the ciliary body to move closer to the lens.
 This causes the tension on the suspensory ligaments to slacken.
 This results in tension on the lens being released.
 The lens becomes more convex and rounded, increasing the refractive power
of the lens.
 The focal length decreases, bringing the object into focus onto the yellow spot of
the retina.
Distant vision (long lens) - When viewing an object at a distance of more than 6
metres:
 At rest, the eyes are set for distant vision. (When people daydream, they have a
faraway look because their eyes are set for distant vision.)
 The ciliary muscles relax, causing the ciliary body to pull back from the lens.
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


This causes the tension on the suspensory ligaments to increase, so they
become taut (pull tight).
This results in the lens pulling to a longer, thinner shape (less convex),
decreasing the refractive power of the lens.
The focal length increases, bringing the object into focus onto the yellow spot of
the retina.
Pupillary mechanism (reflex):
The pupillary mechanism is a reflex action regulated by the Autonomic Nervous
System, to prevent excess light from passing into the eye at one time. Excess light
will cause damage to the retina and the photoreceptors (rod and cone cells). The iris
functions to control the amount of light that enters the eye by controlling the size of
the pupil. The circular and radial muscle fibres in the iris regulate the size of the
pupil.
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Visual defects:
Short-sightedness
This is also called myopia or near-sightedness. It is a refractive defect where the
image focuses in front of the retina because the cornea is too rounded. Distant
objects are seen as blurred. Myopia may be genetic or it may result when people
place regular strain on their eyes by working on computers or in a job where they are
required to focus closely on objects, like microscope work. Glasses and contact
lenses that are concave [)(] are prescribed to reduce refraction. Refractive surgery
may be an option, where the cornea is reshaped to flatten it and so decrease
refraction. This causes the image to be focused onto the retina.
Long-sightedness
This is also called hypermetropia or farsightedness. This is a refractive defect where
the image focuses behind the retina. The person will not be able to see objects when
they are close by, as the images are blurred. This condition is caused by the
following:
 An eyeball that is too short (genetic): This is corrected with prescription
eyeglasses or contact lenses which assist to increase refraction of light by using
convex lenses [()].
 When the lens cannot become round enough during accommodation: This may
be genetic or it may be as a result of aging. As one ages, the ciliary muscles are
unable to contract enough to cause the lens to become rounder. Eyeglasses or
contact lenses are prescribed to assist to increase refraction of light by using
convex lenses [()].
 A cornea that is too flat: Refractive surgery is performed in extreme cases.
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Astigmatism
This is an optical defect that results in blurred vision. It is caused by an irregular
curvature of the cornea or the lens so the eye has different focal points that occur
in different planes. Glasses and hard contact lenses correct the irregular focal points.
Cataracts
This is the clouding of the lens when the lens cortex liquefies to form a milky white
fluid. Cataracts progress over time and may result from long-term exposure to ultraviolet light, radiation, diabetes, hypertension, old age and physical trauma.
Genetically, people may have a predisposition to cataracts. Cataracts must be
removed surgically. Extra-capsular surgery (ECCE) can be used to remove the lens,
leaving the lens capsule intact. Intra-capsular surgery (ICCE) is used when both the
lens and capsule are removed. The lens is replaced with a plastic lens in both
cases.
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The Human Ear:
The ears are the sense organs for hearing. Mechanoreceptors in the ear are
stimulated by sound waves, which are converted to impulses. The impulses are
transmitted via sensory neurons to the auditory centre in the cerebral cortex of the
brain where they are interpreted. The ears are also the organs for balance and
equilibrium. These impulses are transmitted via sensory neurons to the cerebellum
where they are interpreted to ensure balance and equilibrium.
[Please note typo on the diagram: ossicles and not ossides]
The Human Ear
Path of Sound
Sound waves move from the vibrating source (for example, a person talking or a car
driving past) in horizontal waves. Humans hear sounds with a vibration frequency of
between 16 and 20 000 Hz.
 Sound waves are collected by the pinna and passed down the external auditory
canal.
 The vibrations reach the eardrums (tympanic membranes).
 The eardrum vibrates according to the frequency of the sound waves.
 The vibrations are transmitted to the three ossicles (the hammer, anvil and
stirrup) in the middle ear, to amplify the vibrations.
 The stirrup passes the vibration through the oval window, into the inner ear.
 The oval window vibrates and causes wave movements in the liquid of the
perilymph.
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




The wave movements are transferred to the endolymph inside the cochlea.
The hair cells of the organs of Corti (the mechanoreceptors) brush or bend
against the membranes, which converts the mechanical stimulus of the sound
wave into an impulse.
The impulse is passed through the auditory nerve to the auditory centre in the
cerebral cortex of the brain.
The sensation of sound is perceived and interpreted by the cerebral cortex.
Excess vibrations are passed out through the round window, to prevent sound
pressure and echoes.
Balance and equilibrium:
Maintaining balance and equilibrium with regard to the perception of head
movements: function of the semi-circular canal is a swelling called the ampulla,
which contains fine sensory hair cells called crista. The crista are embedded in a
dome-shaped gelatinous capsule. When the head moves, the endolymph in the
ampulla moves as well stimulating the crista and a nerve impulse is discharged and
transmitted to the cerebellum.
Maintaining balance and equilibrium with regard to perception of the position
of the head in relation to gravity: function of the sacculus and utriculus contain
sensory hair cells called macula. Hairs are embedded in the otolithic membrane
covered with calcium carbonate granules, which lie on the hair cells. When the head
position changes, the otoliths move according to the pull of gravity. This stimulates
the maculae, which convert the stimulus into an impulse transmitted to the
cerebellum.
Hearing defects
Middle ear infection: called otitis media and refers to an inflammation of the
middle ear. When the middle ear becomes infected by bacteria, there is extreme
pain as pressure builds up behind the eardrum caused by pus that collects in the
middle ear cavity. The Eustachian tube becomes blocked so there is a lack of the
ability to equalise the pressure on both sides of the eardrum. In some cases, the
eardrum can burst and pus drains out of the ear. Antibiotics are generally prescribed.
Severe scarring of the eardrum can affect the person’s hearing. Ear-nose-and-throat
specialists (ENTs) will insert little rubber structures called grommets into the
eardrum. Grommets look like mini dumbbells with a hole through the centre. This
allows fluids and pus to drain out from the middle ear, preventing the pressure that
causes earache.
Deafness:
The terms ‘hearing impairment’, ‘hard of hearing’ or ‘deafness’ mean that the person
has a loss of the ability to detect sounds either partially or completely.
Hearing aids and cochlear implants:
A hearing aid is an apparatus that is worn in or behind a person’s ear. The apparatus
amplifies sound, so that the person is able to hear better. Hearing aids are
generally used when hearing deteriorates gradually. A cochlear implant is a
surgically implanted electronic device that stimulates the auditory nerves with an
electronic field, inside the cochlea. Cochlear implants are used when a person has
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severe hearing loss or impairment. It is a very expensive procedure and requires
much therapy to assist the deaf person to become accustomed to the devise.
SECTION C:
HOMEWORK QUESTIONS
QUESTION 1: 35 minutes
(Modified from various DoE exam papers)
Study the diagram of the eye and answer the questions that follow:
1.1.
1.2.
1.3.
Name the parts numbered 1 to 15.
(15)
Name the functions of the iris, choroid and lens.
(12)
Label in the correct order, all those parts that would indicate the path of light
stimulus from the point where it enters the eye until it reaches the brain.
Provide the number and the name of each structure in order.
(8)
[35]
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QUESTION 2: (Modified from various DoE exam papers)
Study the diagram below and answer the questions that follow:
2.1. State
the letter and
name of the
part
2.2.
2.3.
2.4.
associated with each of the following statements:
a) the part that secretes cerumen (ear wax)
b) the part that intensifies sound waves
c) the part that carries impulses to the brain
d) the part that is responsible for balance
e) the part that ensure that the air pressure is equal on both sides of the
eardrum
Explain what would happen if part F was blocked.
Describe the sequence of events that occur between the entry of a sound
wave into the ear canal, until it reaches the auditory nerve.
Briefly discuss what a middle ear infection is and how this is solved.
SECTION D:
SOLUTIONS FOR SECTION A
QUESTION 1:
1.1. B
1.2. C
1.3. C
1.4. A
1.5. C
1.6. D
1.7. C
1.8. C
1.9. B
1.10. B
1.11. D
© Gauteng Department of Education
(2)
(2)
(2)
(2)
(2)
(4)
(14)
(10)
[38]
57
1.12.
1.13.
1.14.
1.15.
B
A
C
C
(15 x 1) = (15)
QUESTION 2:
- In bright light the pupil size was small 
- to reduce the amount of light entering the eye 
- Now in dimly lit room the pupil size has to increase 
- to increase the amount of light entering the eye 
(4)
QUESTION 3:
3.1. 1 = cornea 
2 = pupil 
3 = suspensory ligaments 
3.2. Number 2 , the iris 
3.3. The radial muscles of the iris relax 
the circular muscles contract 
this will cause the pupil to constrict 
allowing less light to enter into the eye 
3.4.
3.5.
3.6.
Part 4 = the lens focusses the light rays onto the retina at the back of the
eye  .
Part 7 = the viterous body / viterous humor is part of the refracting medium of
the eye and helps to maintain the shape of the eyeball 
Number 6 = the ciliary muscles in the ciliary body 





The ciliary muscles contract 
Releasing the tension on the suspensory ligaments so they become
relaxed 
The tention on the elastic lens becomes less 
The lens becomes rounder/more convex 
This increases the refraction of light through the lens sothat the image
focusses on the retina 
(18)
QUESTION 4:
4.1
B : Semi-circular canals 
G : Auditory meatus/canal  (4)
4.2
C : Transmits pressure waves to the perilymph of the inner ear  (2)
E: Prevents pressure build-up of sound waves / distortion /eases vibrations
out of the inner ear/ absorbs vibrations (any two) (2)
4.3
(a)
 A buzzing sound is caused by a difference in the pressure between the outer and
the middle ear 
 Swallowing opens / closes the Eustachian tube 
 to equalize the pressure (3)
(b)
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

4.4
To amplify 
Sound  (2)
(a) No  (1)
(b) It is not moveable or flexible  for more accurate collection of sound 
/ for finding the direction  that the sound is coming from  (2)
4.5
Both receive  stimuli  and convert  to impulses  which they send through
the sensory neuron  (Any 2 x 2)
= (4)
4.6
Larger surface area  to accommodate more receptors fits into smaller area /
takes up less space  (Any 2) = (2)
SESSION NO: 8
CONSOLIDATION: NUCLEIC ACIDS, MEIOSIS, GENETICS AND INHERITANCE
Note to teacher: Sessions 8, 9 and 10 are consolidation sessions where learners
will get an idea of what to expect in the exam as questions have been extracted from
past examination papers to assist with exam technique and time allocation. Please
make sure that they adhere strictly to the time allocations for each question.
Show learners that they will find that there are questions that combine sections/topics
of work covered. Please make sure that they do not learn topics as individual units,
but that you understand how they interrelate. Meiosis, DNA and Genetics combine
well, as does the Nervous system, Hormone regulation and Homeostasis although at
this point they have not as yet complete Hormones and Homeostasis. Remind the
learners to keep this in mind when preparing for their exams.
Please note that there are no content summaries included in Consolidation sessions
so there is no Section B. Refer to the previous sessions should learners need to
check up on content information.
When answering questions in an exercise, test or exam:
 Read the question first and underline the operative words so that you are clear
about what is being asked of you.
 Take careful note of the mark allocation, as this will guide you to the number
of facts that you need to write. Do not waste time writing 5 facts when the
examiner only asked for 2. They will only mark the 1st two answers.
 Answer the question as if you are answering someone whom you like, is
intelligent but knows nothing about Life Science – then you will not leave
anything out.
 Please note: an examiner will never ask 2 questions with the same answer. If
you have written the same answer then one of them is definitely wrong.
Please re-read each of the questions and you will see that each one requires
a different answer.
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

If you are asked to ‘tabulate’ – then you MUST answer in the form of a table.
You will be penalized if your points are not listed in a table format. You will
also receive a mark for drawing the table and the appropriate headings.
When you are asked to compare two things/aspects/component/terms, then
rather use the table format. This way you will remember to write equally about
both of the factors and compare fact /characteristic properly.
When answering questions with diagrams:
 Study the diagram and write missing labels in on the diagram itself FIRST.
 Now read through the questions and answer each one.
 If you do not know the answer, then write the number on your answer page,
look at the mark allocation and leave enough lines to write the answer in later,
i.e.: if the mark allocation is 2, then leave two lines open.
Graphs and Pie-charts:
 Make sure that you know the difference between a Line graph, Bar graph,
Histogram and a Piechart.
 Make sure that you practice the skill of graphing and representing data from a
table as a graph.
 Make sure that you are able to read information from a graph accurately. Use
a ruler and draw lines on the graph – through the X and Y axis so that your
readings are accurate.
Calculations:
 You will be expected to do calculations in a test and exam.
 Make sure that you take a calculator in with you.
 Make sure that you understand how to calculate the average, the difference
between and percentage.
 Generally, the examiner will ask you to show your calculations. You must
write out your calculation step by step otherwise you will only be awarded a
mark for the answer – if it is correct.
 Always add the unit to your answer (if there is one).
1.
2.
3.
Introduce session – 5 minutes (and go over basic exam techniques as per
the above hints)
Typical exam questions and solutions – 55 minutes
(Questions that are not completed must please be included with Homework)
Answer/memo discussion – 30 minutes
SECTION A: TYPICAL EXAM QUESTIONS
QUESTION 1:
10 Minutes
(Taken from DoE November 2008 Paper 1)
Some people have the ability to roll their tongue (rollers) while other people cannot
roll their tongues (non-rollers).
A Grade 12 learner wanted to determine the frequency of learners in the school that
could roll their tongues. She went to each grade in the school and counted the
© Gauteng Department of Education
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number of rollers and non-rollers. She presented her results in the graph below.
1.1.
1.2.
1.3.
State a hypothesis for this investigation.
Which grade had the most learners that could roll their tongues?
Use the data in the graph to draw a table that shows the results she
obtained.
Calculate the ratio of rollers to non-rollers. Show ALL working.
(2)
(1)
(7)
1.4.
(4)
[14]
[Remember: to give the table suitable headings/captions. Always compare the
same characteristics for each point in the columns]
QUESTION 2: 8 Minutes
Two newborn babies were accidentally mixed up at the hospital. In an effort to
determine the correct parents of each baby, the blood types of the babies and the
parents were determined as follows:
Baby 1 – type O
Mr Smith – type AB
Mr Jones – type B
2.1
2.2
Baby 2 – type A
Mrs Smith – type B
Mrs Jones – type B
Who are the parents of Baby 2?
Provide evidence for your answer in 4.1 by showing your working in a
Punnett square.
[ Remember: Blood group is a result of multiple alleles and is an
example of co-dominance. A and B are equally dominant and will
dominate over O. Blood type O can only occur if both alleles are
recessive = ‘OO’]
© Gauteng Department of Education
(2)
(6)
[8]
61
QUESTION 3:
12 minutes
(Taken from various sources)
3.1. Where is DNA found?
(2)
3.2. What are the constituent groups of molecules that form the nucleotides?(3)
3.3. Name the pyrimidines and purines of DNA and RNA.
(6)
3.4. Name the mRNA produced by each of the following strands of DNA:
a)
AACGGCTAT
(1)
b)
CCGTAACGAATT
(1)
c)
GCGAATTCA
(1)
[14]
QUESTION 4:
3 minutes
(Taken from various sources)
A child is born out of wedlock and the mother wants to find out who is the father of
the child. Using the DNA fingerprints below determine who the father of the child is.
Explain your answer.
(3)
[Hint: Remember to ALWAYS use a ruler horizontally across the strands so
that you do not make a mistake when comparing the VNTR markers. Place a
mark next to each VNTR marker that corresponds]
QUESTION 5:
20 minutes
(Taken from various sources)
Study the diagrams below on the principle of meiosis. Answer the questions that
follow:
[Hint: Remember to ALWAYS first label the diagram before going on to the
questions]
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a)
b)
c)
d)
e)
How many chromosomes does cell B have?
Would this be n or 2n? Give a reason for your answer.
How many chromosomes does each cell in F have?
What would the ploidy of each cell in F be?
Does each cell in F have exactly the same number of chromosomes?
(1)
(2)
(1)
(1)
(1)
5.2.
Tabulate the differences between meiosis 1 and meiosis 2.
[Hint: Remember to give the table suitable headings/captions.
Always compare the same characteristics in each of the columns)
(8)
5.3.
5.4.
Why is meiosis important in the formation of sex cells?
What is the significance of crossing over during prophase I?
(4)
(2)
[20]
QUESTION 6: 7 Minutes
(Taken from DoE Nov 2011 Paper 1)
Study the diagram below, which shows three generations of snapdragon plants
and answer the questions which follow.
Use the following symbols for the contrasting alleles:
W – for white flowers
R – for red flowers
[HINT: you have been told to use W for white flowers. So a homozygous white
flower will be WW. A homozygous red flower will be RR. This means that a
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63
heterozygous flower will be WR. Do NOT use any lower case letter for the
recessive gene because you have been provided with the symbols for the
alleles. ONLY use the W and the R]
6.1
6.2
State the kind of dominance shown in the diagram above. (1)
Use the symbols R and W and write down the genotypes of each of
the following snapdragon plants:
a)
A
(2)
b)
B
(2)
c)
C
(2)
[7]
SECTION C:
HOMEWORK QUESTIONS
QUESTION 1:
26 minutes
The following diagram illustrates the formation of mRNA using a single strand of a
DNA molecule as a template. Study the diagram and answer the questions that
follow.
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[Hint: Remember to ALWAYS first label the diagram before going on to the
questions]
1.1.
1.2.
1.3.
1.4.
1.5.
Identify the parts numbered 1 to 12.
(12)
Name the chemical bond at X.
(1)
Where in a cell does the process illustrated in the diagram occur and
when?
(2)
Tabulate three differences between RNA and DNA.
(7)
[Hint: Remember to give the table suitable headings/captions. Always
compare the same characteristics in each of the columns)
How do mRNA and tRNA differ with respect to structure and function? (4)
[26]
QUESTION 2:
12 Minutes
The pedigree for albinism is inherited as an autosomal recessive trait. The trait is not
sex linked and is shown by both males and females. The affected female in the third
generation has phenotypically normal parents. Refer to the diagrams on the following
page and answer the questions that follow from the diagram and from your
knowledge.
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Use the following symbols to understand the pedigree
Normal female
Affected female
Carrier
Affected male
Normal male
Carrier (heterozygote
2.1
2.2
2.3
2.4
3.5
What change would occur in the genetic structure for albinism to arise?
List 2 characteristics shown in the phenotype of a person with albinism.
Explain what is meant by autosomal recessive trait.
Distinguish between genotype and phenotype.
Explain how:
(i)
All generation II offspring are carriers for the albino allele.
(ii)
III-2 is an albino girl whose paternal grandmother and maternal
grandfather are also albinos.
(iii)
All her other relatives in Generation III show normal phenotypes.
[Hint: remember that albinism is a mutation]
(1)
(2)
(2)
(3)
(6)
[14)
QUESTION 3:
10 Minutes
(Taken from DoE Feb/March 2009 Paper 1)
An investigation to determine the effect of increasing radiation on lethal (deadly)
mutations on X chromosomes in fruit flies was undertaken by scientists.
The results are shown in the graph that follows:
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3.1.
3.2.
3.3.
3.4.
3.5.
3.6.
Formulate a possible hypothesis for this investigation.
(2)
Name ONE factor that was varied by the scientists in this investigation.
(1)
How many different values of the factor named in QUESTION 1.2 above
were used?
(1)
Name TWO factors that would have to be kept constant during this
investigation.
(2)
What conclusion can be drawn from the results presented in the graph? (2)
If you were carrying out this investigation, describe ONE way in which you
would ensure that the results obtained are reliable.
(2)
[10]
SECTION D:
SOLUTIONS FOR SECTION A
QUESTION 1:
1.1
Most  learners in the school can roll their tongue 
OR
Most  learners cannot roll their tongue 
OR
Equal  number of rollers and non-rollers 
OR
Difference  in the number of rollers and non-rollers 
OR
Tongue rolling occurs /does not occur among the learners 
1.2
Grade 10 
1.3
The number of rollers and non-rollers in the different grades
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(2)
(1)
67
OR
The number of rollers and non-rollers in the different grades
Caption 
Correct column headings 
Correct row headings 
Data in table:
5 rows correct 
3 to 4 rows correct 
1 to 2 rows correct 
Drawing of table as blocks with columns and rows 
(7)
1.4
160 + 150 + 180 + 140 + 120 = 750 
40 + 50 + 20 + 60 + 80 = 250 
750 ÷  250 OR 750/250 
3 : 1  OR 75% : 25% OR 1 non-roller: 3 rollers
(4) [14]
QUESTION 2:
Baby 2 – type A
2.1. Parents are Mr and Mrs Smith√√
2.2. P1 Mr Smith AB x
Mrs Smith B
P1 IAIB √
X
IBIB OR IBi√
(2)
Punnett square:
IA
IB
IB IA IB IB IB
i
IA i
IB i
gametes √√
Punnett square correctly done√√√
F1: blood type A √ or AB √ or B √
Only Mr and Mrs Smith could have a baby with type A √ blood or I Ai √
(12 x half = 6)
QUESTION 3:
3.1. DNA is found in the threadlike chromosomes in the nucleus of a living
cell 
3.2. A phosphate ion ,a pentose sugar  and a nitrogenous base  (3)
3.3. Pyrimidines of DNA – cytosine and thymine 
Pyrimidines of RNA - cytosine  and uracil 
Purines of DNA and RNA – adenine and guanine 
(6)
3.4. a)
UUGCCGAUA 
(1)
b)
GGCAUUGCUUAA 
(1)
c)
CGCUUAAGU 
(1)
© Gauteng Department of Education
(2)
68
QUESTION 4:
Male 2 is the father .
The child has more matching bands in common with the mother and male 2 than
with the mother and male 1 
(3)
QUESTION 5:
5.1. a)
4
(1)
b)
2n  . There are two sets of chromosomes  / the homologous pairs of
chromosomes are present  (2)
c)
2
(1)
d)
n / haploid 
(1)
e)
Yes 
(1)
5.2.
This answer must be in table form.
Meiosis 1
Meiosis 2
Prophase: Chromosomes are in
homologous pairs.
Chromosomes are not in
homologous pairs.
Prophase: Crossing over occurs.
No crossing over occurs.
Metaphase: Chromosomes are
arranged at the equator in pairs.
Chromosomes are arranged
randomly at the equator.
Anaphase: One of each pair of
chromosomes moves to opposite
poles.
The centromere does not split.
Daughter chromosomes move to
opposite poles.
The centromere splits.
Telophase: One complete set of
chromosomes reaches each pole.
A nuclear membrane does not
reform.
Daughter chromosomes reach
opposite poles.
A nuclear membrane reforms around
each nucleus.
Two daughter cells form with the
haploid number of chromosomes.
Four daughter cells form the haploid
number of chromosomes
(Mark any 3 correct answers for each of Meiosis 1 and 2. Allocate 1 mark for
the table and 1 mark for the correct headings per column)
(8)
5.3.
5.4.
The sex cells / gametes must contain one set of chromosomes only so that
when the zygote is formed after fertilisation , it will contain two sets of
chromosomes 
(4)
Crossing over ensures genetic variation within a species 
(2)
QUESTION 6:
6.1. Incomplete dominance (1)
6.2. (a) RR/CRCR
(b) RW /CRCW
(c) WW/CWCW (6)
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SESSION NO: 9
CONSOLIDATION: RESPONDING TO THE ENVIRONMENT: HUMANS
(NERVOUS SYSTEM, EYE AND EAR)
Teacher note: Refer to Session 8 for tips on answering exam questions. Please
ensure that the learners adhere to the time limits so that they learn to work under
pressure. Let the class work through each question within the time limit.
1.
2.
3.
Introduce session – 5 minutes (and go over basic exam techniques as per
the above hints)
Typical exam questions and solutions – 55 minutes
(Questions that are not completed must please be included with Homework)
Answer/memo discussion – 30 minutes
SECTION A: TYPICAL EXAM QUESTIONS
QUESTION 1:
16 minutes
(Taken from various DoE Paper 2)
Study the diagram below and answer the questions that follow:
1.1.
1.2.
1.3.
What is meant by the term ‘reflex action’?
(4)
Provide a reason why reflex actions are of importance to the human body. (2)
Name the structures, that are missing on the diagram and in their correct
order, that will ensure that an individual does not burn his/her finger.
(3)
[Hint: think about the neurons involved – in the correct order to ensure
that the hand is pulled away]
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1.4.
Name the microscopic gap that will transmit impulses between the structures
named in QUESTION 1.3.
(1)
1.5. In this reflex action above, name the:
(i)
stimulus
(1)
(ii)
effector
(1)
1.6. Tabulate THREE differences between a motor neuron and a sensory
neuron.
(7)
[17]
QUESTION 2:
10 minutes
(Taken from DoE Nov 2005 Paper 2)
Study Diagrams I and II that illustrate the lens and parts of one layer of the human
eye, as well as the graph below and answer the questions that follow.
[HINT: label the diagram first, study the graph and then answer the questions]
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2.1
2.2
2.3
2.4
2.5
Identify parts A and B.
(2)
Which Diagram (I or II) shows parts of the eye:
(i) where the ciliary muscles are contracted
(1)
(ii) are under dim light conditions
(1)
Explain your answer in QUESTION 2.2 (i).
(2)
Which letter on the graph indicates each of the following:
(i) The eye looking at a nearby stationary object
(1)
(ii) The eye looking at an object moving towards the viewer
(1)
[Hint: the eye is normally set for distant vision when it is relaxed. The
lens must be accommodated to adjust to view an object as it moves
closer to the viewer.]
Explain the significance of the elastic nature of the lens.
(2)
[10]
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QUESTION 3: 17 minutes
(Taken from DoE Nov 2005 Paper 2)
Study the following diagrams and table and answer the questions that follow.
Table indicating how much of the human brain’s sensory area is allocated to certain
body parts, depending on the number of sensory receptors on the part:
[HINT: label the diagrams first and then start with the questions]
3.1
3.2
3.3
3.4
3.5
Identify parts A and D.
(2)
After only the sensitive coverings of the brain were injected to make them
insensitive, part C of a normal person was pierced with a sharp object, but the
person did NOT experience any pain.
(i)
Give a possible explanation for the person not experiencing a pain
sensation.
(3)
(ii)
Explain a possible disadvantage if a body part is pierced with a sharp
object, but the person does not experience any pain.
(2)
(i) Give the letter of the part that will interpret impulses conducted along
part B.
(1)
(ii) Explain your answer in QUESTION 3.3 (i).
(2)
Explain why damage to part F may lead to immediate death.
(2)
Give a possible explanation for the high representation of the tongue in the
sensory area of the brain as compared to the leg.
(2)
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3.6
(i) With which body part shown in the table, will the abdomen most probably
have the same size area representation in the sensory part of the brain?(1)
(ii) Explain your answer in QUESTION 3.6 (i).
(2)
[17]
QUESTION 4:
30 minutes
(Modified from Study & Master Grade 12 –old syllabus)
Study the diagram of the human eye and answer the questions that follow:
[HINT: label the diagrams first and then start with the questions]
4.1.
4.2.
4.3.
4.4.
4.5.
4.6.
4.7.
Write down the number and the name of the layer:
a) giving colour to the eye
(2)
b) that prevents the reflection of light rays in the eye
(2)
c) which contains rod and cones
(2)
Write down the number and name of the structure:
a) mainly responsible for the refraction of light rays
(2)
b) where the clearest image of the object is formed.
(2)
Write down the numbers and names of FOUR parts which refract light rays
in order, as they pass through the eye.
(4)
Write down the number and name of the layer which changes light
energy into nerve impulses.
(2)
Write down the number and name of the layer of the structure which
controls the amount of light entering the eye.
(2)
Explain the process and functioning of the structure named in
QUESTION 4.5, when there is bright light.
(4)
Explain the process that takes place in the eye when we focus on an
object that is closer that 6m.
(8)
[30]
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QUESTION 5:
15 minutes
(Taken from DoE Nov 2005 Paper 2)
A person hears a car moving out of control and crashing into another vehicle.
Describe the events that will lead to the person hearing the crash.
[Hint: think about the path of sound as the sound waves travel through the
ear]
Content: (15) Synthesis: (3)
[18]
SECTION C:
HOMEWORK QUESTIONS
QUESTION 1:
10 Minutes
Study the diagram below and answer the questions that follow:
1.1.
1.2.
1.3.
1.4.
1.5.
1.6.
Supply a suitable heading for the diagram.
(1)
Label the parts numbered 1, 2, 5 and 6.
(4)
What number represents a synapse?
(1)
What type of neuron has been left off the diagram?
(1)
Name the end point of the structure named in QUESTION 1.4.
(1)
If part number 6 is damaged, what will the consequences be for the body? (3)
[11]
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QUESTION 2:
14 Minutes
(Taken from various DoE exam papers)
Study the passage and diagram below and answer the questions that follow:
Under certain abnormal conditions, the middle ear can become filled with a thick, sticky
mucus. This condition is known as ‘glue ear’ It affects mainly children. To treat this
condition, surgeons are required to drain the mucus and reduce the pressure in the
middle ear. They do that by placing a very small tube called a ‘grommet’ in the
membrane labelled A in the diagram below.
2.1.
2.2.
2.3.
2.4.
2.5.
Identify parts numbered A, B, C and E.
State two consequences of a build-up of pressure in the middle ear.
Explain the effect on the functioning of part B should mucus be left to
accumulate in the child’s middle ear.
Explain the function of part E.
Once a ‘grommet’ is in place, the child should not go swimming.
Give two reasons for this precaution.
(4)
(2)
(2)
(2)
(4)
[18]
QUESTION 3: 7 Minutes
A person took part in an experiment on the eye’s response to light. A lamp was
placed at seven different positions from the person’s face. The diameter of the
person’s pupil was measured at each position.
The table below shows the diameter of the person’s pupil when the light was placed
at various distances from the person’s face.
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3.1.
3.2.
Position of the lamp
Diameter of the pupil (mm)
1
2
3
4
5
6
7
1,2
1,8
2,4
3,0
3,6
4,2
4,8
(i) At which position was the lamp furthest from the eye?
(1)
(ii) Explain your answer to QUESTION 3.1 (i).
(2)
The lamp was moved from position 1 to position 2. What happened to the
muscles in the iris of the eye, that caused the change in the diameter of
the pupil?
(4)
[7]
SECTION D:
SOLUTIONS FOR SECTION A
QUESTION 1:
1.1. A fast automatic response by an effector  (muscle / gland) to a stimulus
received by a receptor  (any 4 = 4 marks)
1.2. protects the human body against damage OR
regulates secretions from glands  (2)
1.3. - sensory neuron / afferent neuron / unipolar neuron / monopolar neuron
(must be mentioned first) 
- connector neuron / inter neuron (if mentioned second) 
- motor neuron / efferent neuron / multipolar neuron (if mentioned third) (3)
1.4. Synapse (1)
1.5. (i)
heat / flame / candle fire  (1)
(ii)
muscle in the arm to pull the hand away (1)
1.6.
Motor neuron
Sensory neuron
Conducts nerve impulses
Conducts nerve impulses
away from the central nervous towards the central nervous
system
system
Axon only myelinated
Both axon and dendrite
myelinated
Only multipolar structures
Unipolar / Monopolar or
Bipolar structures
Many dendrites
One dendrite
(Any three difference per neuron PLUS 1 mark for the table and correct
captions)
(7)
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QUESTION 2:
2.1
A: Ciliary body/Ciliary muscle 
(1)
B: Suspensory ligament 
(1)
2.2
(i) Diagram II 
(1)
(ii) Diagram I 
(1)
2.3
Suspensory ligament slackens OR
Lens looks smaller/ more convex
(2)
2.4
(i) D (1)
(ii) F (1)
2.5
- Can change its shape 
- to focus image onto the yellow spot 
- irrespective of the distance from the eye 
OR for near or distant vision OR for accommodation  (3)
QUESTION 3:
3.1. A: Eustacian tube 
(1)
B: Corpus callosum 
(1)
3.2. (i)
- absence of pain receptors 
- thus no impulse is generated
- to be interpreted by the brain
OR
- Cerebrum is damaged 
- any impulse received 
- cannot be interpreted 
(3)
(ii)
- pain is a protective function 
- part could be lost or damaged 
- and loose its function for the body 
- because the person is unawre of the harm 
- therefore does not respond appropriately / correctly 
- leading to further damage  (Any TWO = 2)
3.3. (i) E
(1)
(ii) - originates from part of the ear containing the balance receptrs 
- and E / cerebellum controls balance 
(2)
3.4. Vital processes  will stop / breathing and hearbeat will stop (1)
3.5. - tongue is more sensitive / is a sense organ
- has more receptors 
- is needed for the reception of a large variet of stimuli ANY TWO = (2)
3.6. (i) Hand / upper arm / leg
(1)
(ii) Has more or less the same amount of receptors as the abdomen (2)
QUESTION 4:
4.1. a) 2 – iris 
(2)
b) 9 – choroid 
(2)
c) 10 – retina 
(2)
4.2. a) 6 – cornea 
(2)
b) 12 - yellow spot / fovea centralis  (2)
4.3. 6 – cornea 
5 – aqueous humour 
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4.4.
4.5.
4.6.
4.7.
3 – lens 
7 – vitreous humour 
(Answer must be in the correct order with correct number AND structure) (4)
10 – retina 
(2)
2 - iris 
(2)
Bright light:
 circular muscles contract 
 causing pupil to constrict (get smaller) 
 radial muscles relax 
 less light is allowed into the eye 
(4)
Near vision:
 ciliary muscles contract causing the ciliary body to move closer to the
lens 
 suspensory ligaments slacken 
 tension on the lens is released 
 lens becomes more convex and rounded increasing the refractive
power of the lens 
 focal length decreasesbringing the object into focus onto the yellow
spot of the retina 
(8)
QUESTION 5:
 Collision / crash causes vibrations
 That generate sound waves
 Which are transmitted by the air
 The pinna directs the sound waves
 Along the auditory canal
 The sound waves cause the tympanic membrane
 To vibrate
 And the vibrations are transferred to the ossicles
 Which will amplify the waves
 And transmit the vibrations to the oval window
 Which will also vibrate to transfer the sound waves to the perilymph
 The vibrations are then transferred to the endolymph
 Where the organs of Corti / hair cells / mechanoreceptors
 Situated in the cochlea
 Convert the sound waves into nerve impulses
 Which are conducted via the auditory nerve
 To the hearing centre
 In the brain / cerebrum
 Where the sensations of hearing are experienced (ANY 15 = 15 marks)
Assessing the presentation: (3)
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Criterion
Generally
Relevance (R)
All information
provided is relevant
to the topic
Logical sequence (L)
Ideas are arranged in a
logical/cause-effect
sequence
Comprehensive (C)
All aspects required
by the essay have
been sufficiently
addressed
In this
essay
[18]
SESSION NO: 10
CONSOLIDATION: HUMAN REPRODUCTION
Teacher Note: Refer to Session 8 for tips on answering exam questions. Please
make sure that the learners all adhere to the time limits so that they learn to work
under pressure. Get the group to answer each question together within the time limit
and then go over the answer with them.
1.
2.
3.
Introduce session – 5 minutes (and go over basic exam techniques as per
the above hints)
Typical exam questions and solutions – 55 minutes
(Questions that are not completed must please be included with Homework)
Answer/memo discussion – 30 minutes
SECTION A: TYPICAL EXAM QUESTIONS
QUESTION 1:
12 Minutes
(Taken from various sources)
[Reminder: there are only 4 basic types of crosses. Make sure you are able to
use them properly. Do a quick cross in pencil, next to the relevant question to
find the correct answer]
Various possible options are provided as answers to the following questions. Choose
the correct answer and write only the letter (A – D) next to the question number.
1. In mammals, fertilization takes place in the
A Fallopian tubes
B vagina
C uterus
D ovary
2. During the development of the embryo, the function of the amnion is to
A give rise to the placenta
B protect the embryo against harmful chemical substances
C enclose the fluid which protects the embryo against injury
D prevent the developing embryo from moving about
3. The following is NOT a function of the placenta of mammals:
A transports nutrients to the embryo
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B removes waste products from the embryo
C protects the embryo against mechanical injury
D protects the embryo against harmful chemical substances
4. The fusion of an egg cell and a sperm cell is known as
A copulation
B cleavage
C fertilization
D ovulation
5. The human embryo obtains:
A nutrients and oxygen from the mother’s blood
B nutrients and CO2 by diffusion across the placenta
C yolk and albumen from the allantois
D nutrients and oxygen by diffusion across the placenta
6. The human foetus is immediately surrounded by the…
A allantois
B amnion
C chorion
D placenta
7. The human foetus is surrounded by
A amniotic fluid
B air
C wastes
D mother’s blood
8.
Fertilization occurs when the….
A sperm penetrates the ovum
B sperm makes contact with the ovum
C nucleus of the sperm fuses with the nucleus of the ovum
D fertilization membrane has formed around the ovum
9.
Which of the following pairs indicates a reproductive structure and its function
accurately?
A Fallopian tube – production of sperm
B Vagina – fertilization
C Uterus – development of the embryo
D Testes – production of the ovum
10. The main function of the amnion and amniotic fluid is:
A shock absorber
B medium that removes excretory waste
C medium from which oxygen is obtained for the growing embryo
D medium in which secretions take place
11.
Which of the following is the hormone responsible for the birth process?
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A
B
C
D
12.
prolactin
oestrogen
progesterone
oxytocin
Dizygotic twins….
A result when one egg cell is fertilized and separates into two structures
B will be identical in genetic inheritance and appearance
C result when two or more eggs are fertilized
D will always be the same sex
(12 x 2) [24]
QUESTION 2: 6 Minutes
(Taken from NSC LS Exam November 2009 paper 1)
Choose an item from COLUMN II that matches a description in COLUMN I. Write
only the letter next to the number.
COLUMN I
2.1. The type of reproduction involving a male gamete that
fuses with a female gamete
COLUMN II
A gestation
B identical
2.2. The type of fertilization that occurs outside the body in a
glass petri dish in a laboratory
2.3. The type of twins formed as a result of the fertilization of
two ova
C placenta
D cancer
E sexual
2.4. The muscular, hollow organ in mammals in which the
embryo develops
F fraternal/ dizygotic/
non-identical
2.5. The period of development of an embryo between
fertilization and birth
G in-vitro
2.6. Forms as a result of uncontrolled division of cells
H asexual
I uterus
(6)
QUESTION 3:
11 Minutes
(Taken from the NSC Exemplar 2008 Paper 1)
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The diagram below represents a part of the human female reproductive system after
copulation. Study the diagram and answer the questions that follow.
3.1.
3.2.
3.3.
3.4.
3.5.
Give labels for parts A, E and G respectively.
(3)
Name the process that takes place at B.
(1)
When, during the menstrual cycle, does the process mentioned in
QUESTION 3.2. take place?
(1)
Describe the process represented by D.
(3)
Write down the number of chromosomes that would be present in the
nucleus of the following:
a)
Cell C
(1)
b)
One cell of F
(1)
c)
Cell H
(1)
[11]
QUESTION 4: 8 Minutes
(Modified from Study and Master Grade 11 – old syllabus)
Study the following diagram and answer the questions that follow:
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4.1.
4.2.
4.3.
Provide labels for the parts numbered 1 to 5.
The structure numbered 1 contains enzymes. What is the function of
these enzymes during fertilization?
The structure numbered 3 is packed with mitochondria. Explain the
relevance of the mitochondria to the sperm cell.
(5)
(2)
(2)
[8]
QUESTION 5: 12 Minutes
(Modified from Study and Master Grade 11 – old syllabus)
The following questions are on the reproduction process in humans.
5.1. Name the function/s of the following structures in the male testes:
a) epididymis
(1)
b) seminal vesicle
(2)
c) prostate gland
(1)
d) Cowper’s gland
(1)
5.2. Name the process by which the ovum is released by the ovary.
(1)
5.3. Where does fertilization of the ovum take place?
(1)
5.4. Name the function during the development of the embryo, of each of the
following structures?
a) chorion and chorionic villi
(3)
b) amnion and amniotic fluid
(3)
c) umbilical cord
(2)
[14]
QUESTION 6: 20 Minutes
(Taken from DoE Exemplar 2014)
Name the hormones produced by the testes and ovaries and describe the role of each
hormone in human reproduction.
Content: (17)
Synthesis: (3)
[20]
NOTE: NO marks will be awarded for answers in the form of flow charts or diagrams.
SECTION C:
HOMEWORK QUESTIONS
QUESTION 1: 20 minutes
(Taken from various NSC
exams)
Describe the menstrual cycle and how it is influenced by different hormones.
Content: (17)
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Synthesis: (3)
SECTION D:
[20]
SOLUTIONS FOR SECTION A
QUESTION 1:
1.1. A
1.2. C
1.3. C
1.4. C
1.5. D
1.6. B
1.7. A
1.8. C
1.9. C
1.10. A
1.11. D
1.12. C
(12 X 2) (24)
QUESTION 2:
2.1. E
2.2. G
2.3. F
2.4. I
2.5. A
2.6. D
(6 X 1) (6)
QUESTION 3:
3.1
A- Ovary  , E- Fallopian tube  , G- endometrium 
(3)
3.2
Ovulation (1)
3.3 day 14/middle of the menstruation cycle (1)
3.4 Fertilization  takes place. The sperm (haploid/n) fuses with the (haploid/n)
egg cell/ovum to form a diploid zygote (2n) - (any 3 points = 3 marks )
3.5
a) 23 chromosomes (1)
b) 46 chromosomes (1)
c) 23 chromosomes (1)
QUESTION 4:
4.1. 1 : acrosome 2 : nucleus  3 : neck  4 : tail  5 : head 
(5)
4.2. digest the plasmalemma of the ovum (to allow penetration of the sperm
cell nucleus)
(1)
4.3. mitochondria produce the energy (ATP) required for the sperm cell to
travel (swim)  (from the vagina through the uterus to the Fallopian tube) (2)
QUESTION 5:
5.1. a) storage of maturing sperm cells
(1)
b) secrete extra fluid to assist with sperm cell motility and fluid
contains nutrients (fructose) as a source of food for the sperm cells (2)
c) secretes an alkaline fluid to neutralize acidity of the vagina  (1)
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5.2.
5.3.
5.4.
d) secretes an alkaline fluid directly into the male urethra to neutralize
any acidity caused by remaining urine  (1)
ovulation 
(1)
in the Fallopian tubes 
(1)
a) chorion develops villi which grow into the placenta and allows:
diffusion of respiratory gases, nutrients and waste materials between
the embryonic and maternal blood; chorionic villi act as a micro-filter
preventing pathogenic substances to pass to the embryo (Any 3)
(3)
b) allows free movement of the embryo; protects against desiccation;
protects against temperature changes (3)
c) contains the umbilical artery and the umbilical vein to transport oxygen
and nutrients to the embryo ; transport carbon dioxide and wastes from
the embryo; it attaches the embryo to the placenta (any 2) (2)
QUESTION 6:
Testosterone
Produced by seminiferous tubules 
in the testes
During puberty testosterone stimulates:
The deepening of the voice as vocal cords elongate in the larynx 
The development of muscles 
The growth of facial, pubic and body hair
Development of the penis and testes
The production of sperm in the testes
max (5)
Oestrogen
Produced by the Graafian follicles
in the ovaries
Causes the lining of the uterus /endometrium
to become thicker/more vascular 
in preparation for a possible implantation of the embryo and development of
the foetus
During puberty oestrogen stimulates:
The widening of the pelvis/hips
The growth and development of the breasts 
The growth of the female sex organs
The start of the menstrual cycle, ovulation and menstruation
max (7)
Progesterone
Produced by the corpus luteum  and placenta
Progesterone causes further thickening of the endometrium 
so that it is ready for implantation of the embryo should fertilisation occur 
High levels of progesterone
inhibits the secretion of FSH 
by the pituitary gland
which in turn prevents the further development of any new ovum in the
ovary 
max (5)
Content (17)
Synthesis (3)
[20]
Assessing the presentation of the essay (synthesis)
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Criterion
Relevance
Elaboration
Mark
All information provided is relevant to the topic
1
Logical
Ideas arranged in a logical/cause-effect
sequence
sequence
Comprehensive Answered all aspects required by the essay
© Gauteng Department of Education
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1