NATIONAL

SENIOR CERTIFICATE

GRADE 12

LIFE SCIENCES P1

NOVEMBER 2009

MARKS: 150

TIME: 2½ hours

This question paper consists of 15 pages.

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INSTRUCTIONS AND INFORMATION

Read the following instructions carefully before answering the questions.

1. Answer ALL the questions.

2. Write ALL the answers in the ANSWER BOOK.

3. Start the answers to each question at the top of a NEW page.

4. Number the answers correctly according to the numbering system used in this
question paper.

5. Present your answers according to the instructions of each question.

6. ALL drawings should be done in pencil and labelled in blue or black ink.

7. Only draw diagrams or flow charts when asked to do so.

8. The diagrams in this question paper are NOT all drawn to scale.

9. Do NOT use graph paper.

10. Non-programmable calculators, protractors and compasses may be used.

11. Write neatly and legibly.

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SECTION A

QUESTION 1

1.1 Various options are provided as possible answers to the following questions.
Choose the correct answer and write only the letter (A to D) next to the
question number (1.1.1 to 1.1.5) in the ANSWER BOOK, for example
1.1.6 D.

1.1.1 The amniotic fluid …

A attaches the embryo to the mother.

B allows for the diffusion of nutrients and oxygen from the mother
to the foetus.
C secretes a hormone to maintain pregnancy.
D acts as a shock absorber to protect the foetus against
mechanical injury.

1.1.2 A couple has four daughters. The chances of their fifth child being
a son is …

A 20%
B 50%
C 100%
D 80%

1.1.3 In which ONE of the following parts of a flowering plant does

meiosis occur?

A Cotyledons
B Pollen grain
C Anther
D Pollen tube

1.1.4 If an analysis of DNA from cells in a human body showed that

thymine made up 15% of the nucleotide bases, then the
percentage composition of guanine making up the DNA would
be …

A 15%
B 70%
C 35%
D 85%

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1.1.5 The events of childbirth listed below are not in the correct
sequence:

1. Placenta expelled from uterus

2. The baby’s head emerges from the vagina
3. Contractions of the uterus begin

The correct sequence is …

A 3 2 1
B 3 1 2
C 2 1 3
D 1 2 3 (5 x 2) (10)

1.2 Give the correct biological term for each of the following descriptions. Write
only the term next to the question number (1.2.1 to 1.2.6) in the ANSWER
BOOK.

1.2.1 The narrow tube through which ova travel from the ovary to the
uterus

1.2.2 The mature structure in the ovary of humans in which an ovum

develops before ovulation

1.2.3 The blood vessel in the umbilical cord which is rich in oxygen and
nutrients

1.2.4 The hormone in humans responsible for the contraction of the

uterus during childbirth

1.2.5 The structure into which the ovule develops after fertilisation

1.2.6 The lower neck of the uterus that opens into the vagina (6)

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1.3 Choose an item from COLUMN II that matches a description in COLUMN I.

Write only the letter (A to I) next to the question number (1.3.1 to 1.3.6) in the
ANSWER BOOK, for example 1.3.7 J.

COLUMN I COLUMN II
1.3.1 The type of reproduction involving A gestation
a male gamete that fuses with a
female gamete B identical

1.3.2 The type of fertilisation that C placenta

occurs outside the body in a
glass petri dish in a laboratory D cancer

1.3.3 The type of twins formed as a E sexual

result of the fertilisation of two
ova F fraternal/dizygotic/non-identical

1.3.4 The muscular, hollow organ in G in-vitro

mammals in which the embryo
develops H asexual

1.3.5 The period of development of an I uterus

embryo between fertilisation and
birth

1.3.6 Forms as a result of uncontrolled

division of cells

(6 x 1) (6)

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1.4 The table below shows the DNA base triplets that code for different amino
acids.

Amino acid Base triplet in

DNA template
Leu (leucine) GAA
His (histidine) GTA
Lys (lysine) TTT
Pro (proline) GGG
Ala (alanine) CGA
Trp (tryptophan) ACC
Phe (phenylalanine) AAA
Gly (glycine) CCT

The following is a part of a sequence of amino acids that form a particular

protein molecule:

Ala His Trp Leu Lys

1.4.1 Name the process by which mRNA is formed from a DNA template. (1)

1.4.2 How many mRNA codons would be involved in forming the portion
of protein shown above? (1)

1.4.3 Write down the sequence of the first THREE mRNA codons (from
left to right) for this portion of the protein. (3)

1.4.4 The following is a sequence of base triplets in DNA:

GAA - GTA - TTT - AAA

(a) If guanine, found in the first base triplet, is removed, explain
how this would affect the structure of the protein. (2)

(b) Name the process that occurs when the sequence of bases in
DNA changes. (1)
(8)

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1.5 The diagram below represents an animal cell in a phase of meiosis.

chromatid

1.5.1 State which phase of meiosis is represented in the diagram above. (1)

1.5.2 Give a reason for your answer to QUESTION 1.5.1. (2)

1.5.3 Identify parts A and B. (2)

1.5.4 How many chromosomes …

(a) were present in the parent cell before it underwent meiosis? (1)

(b) will be present in each cell at the end of the meiotic division? (1)

1.5.5 State ONE place in the body of a human female where meiosis
would take place. (1)

1.5.6 Could the cell represented in the diagram be that of a human? (1)

1.5.7 Explain your answer to QUESTION 1.5.6. (2)

1.5.8 Give TWO reasons why meiosis is biologically important. (2)

(13)

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1.6 An investigation was done to determine the role of petals in insect pollination
in apple flowers. When flowers are self-pollinated, the pollen tubes grow a
little into the stigma and style and fertilisation does not take place.

• 10 flowers with petals and 10 flowers without petals were used.

• After two days the flowers were prevented from further pollination.
• After seven days the extent of pollination and fertilisation was recorded.

The diagrams below show the appearance of the flowers with and without
petals.

stigma
style
anther
ovary

Flower with petals Flower without petals

The results are shown in the table below.

NUMBER
Flower with Flower without
petals petals
Pollen on stigma 158 25
Pollen tubes in the style 86 8
Ovules fertilised 38 4

1.6.1 Give an explanation for the presence of more pollen on the stigmas
of the flowers with petals than on the flowers without petals. (2)

1.6.2 Explain why there are more pollen tubes present in the styles of
both types of flowers than the number of ovules fertilised. (2)

1.6.3 State THREE ways in which this investigation could be improved. (3)
[50]

TOTAL SECTION A: 50

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SECTION B
QUESTION 2
2.1 Study the diagrams below and answer the questions that follow.

bladder F head
G
middle
piece
A
B

C
tail
D
E

Human male reproductive system Human sperm cell

2.1.1 Provide labels for A, B, E and G. (4)

2.1.2 State ONE function each of C and F, respectively. (2)

2.1.3 State the LETTER and NAME of the part where sperm are
produced. (2)

2.1.4 Explain why it is necessary for part D to 'hang outside' the body of
the male. (2)

2.1.5 Name the following:

(a) The cells that secrete a male sex hormone (1)

(b) The hormone that stimulates the development of secondary

sexual characteristics in males (1)
2.1.6 During a vasectomy, part B is surgically cut.
(a) Explain how this procedure will act as a method of
contraception. (2)

(b) Will it be possible for a man who is HIV positive to pass the
HI virus to another person after he undergoes a vasectomy? (1)

(c) Explain your answer to QUESTION 2.1.6 (b). (2)

(17)
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2.2 Study the graph below which shows the menstrual cycle and the influence of
the different hormones on it.

Pituitary/
LH
hypophysis FSH
hormone
levels

Growth of follicle

oestrogen progesterone
Ovarian
hormone levels

Thickness of
uterine lining/
endometrium

0 7 14 21 28
Days
Hormonal regulation of the female reproductive cycle

2.2.1 On which day does ovulation take place? (1)

2.2.2 Between which days does menstruation take place? (1)

2.2.3 State any ONE function of luteinising hormone (LH). (1)

2.2.4 Describe the changes in the level of LH shown in the graph. (3)

2.2.5 Describe the relationship between the level of oestrogen and the
endometrium from day 7 to day 14. (2)

2.2.6 Explain why it is necessary for the level of progesterone in the

blood to increase after ovulation. (2)

2.2.7 Did fertilisation take place in the 28-day cycle illustrated in the
graph? (1)

2.2.8 Explain your answer to QUESTION 2.2.7. (2)

(13)
[30]

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QUESTION 3

3.1 It is possible to trace the inheritance of characteristics such as blood groups

and genetic disorders over a number of generations.

3.1.1 The pedigree diagram below shows the blood groups of individuals
of a family. The blood groups are indicated inside the circle or
square. The blood groups of individuals W and X are not indicated.

Blood
W
group O

Blood
X group A Blood
group B

Blood
group O

Key:
Female

Male

Write down all the possible genotypes of individuals:

(a) W

(b) X (8)

3.1.2 Haemophilia is a blood clotting disorder. Explain why mainly males

suffer from this disorder. (4)
(12)

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3.2 Study the karyotype below of a person suffering from Turner's syndrome.
Females with Turner's syndrome do not develop mature sex organs.

1 2 3 4 5

6 7 8 9 10 11 12

13 14 15 16 17 18

19 20 21 22 23

Karyotype of a person with Turner’s syndrome

3.2.1 State the differences between the karyotype for a normal female
and a female with Turner's syndrome. (2)

3.2.2 Explain ONE effect of the disorder on a female. (2)

(4)

3.3 Tommy carried out a survey to find out if there was a difference between the
numbers of boys and girls who have unattached ear lobes. In his investigation
Tommy observed 120 boys and 100 girls. Of the boys, 102 had unattached
earlobes and of the girls, 80 had unattached earlobes.

3.3.1 What percentage of the boys had unattached earlobes? Show ALL
working. (2)

3.3.2 From his results, Tommy calculated that a greater percentage of

boys than girls in the sample had unattached earlobes. Tommy
concluded that in the human population, more boys than girls have
unattached earlobes.

Suggest TWO ways to improve the investigation. (2)

(4)

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3.4 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
diagrammatically 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)

3.5 Suggest FOUR reasons why more teenagers nowadays have unplanned
pregnancies. (4)
[30]

TOTAL SECTION B: 60

SECTION C

QUESTION 4

4.1 In an experiment to show co-dominance, cows with white fur (W) were
crossed with bulls with red fur (R). All the offspring of the F1-generation have
roan fur (RW). A roan fur consists of patches of white and patches of red fur.
Roan cows and roan bulls were crossed and the results are given below.

Genotype RR RW WW
Number of offspring 120 240 120

4.1.1 Give the ratio of the different phenotypes shown in the above table. (2)

4.1.2 Use the information in the table above to draw a pie-chart showing
the proportions of the different genotypes. (7)

4.1.3 Explain why the cows and bulls with genotype RW have roan fur
and not only red or only white fur. (3)
(12)

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4.2 Humans show differences in characteristics such as fingerprints. Humans

have five main types of fingerprints as shown in the diagram below.

Plain arch Tented arch Loop

Plain whorl Double loop

Types of fingerprints of humans

A fingerprint is a useful way of identifying people and classifying them into

groups. A fingerprint is taken by rolling the right index finger onto an inkpad
and then on a piece of paper.

During a discussion of this topic, a group of learners asked the following

question:

''Which one of the five main types of fingerprints is most common amongst the
learners of this school?''

4.2.1 State any FOUR steps in the planning process that must be
considered when planning an investigation to answer the question
above. (4)

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4.2.2 The learners carried out an investigation and the results are shown
in the table below.

Main types of Number of

fingerprints learners
Plain arch 123
Tented arch 112
Loop 124
Plain whorl 150
Double loop 50

(a) Give a caption for the table. (2)

(b) Learners came to the following conclusion:

Most learners have the plain arch-type fingerprint.

Is this a valid conclusion? (1)

(c) Give a reason for your answer to QUESTION 4.2.2 (b). (2)

4.2.3 State the following:

(a) TWO advantages of having a fingerprint database of every

citizen and visitor in South Africa (2)

(b) TWO disadvantages of having a fingerprint database of every

citizen and visitor in South Africa (2)
(13)

4.3 Using genetically modified organisms as a source of food is supported by

some people and rejected by others.

Explain SIX advantages of using genetically modified organisms as a source

of food. (12)

Synthesis: (3)
(15)
[40]

NOTE: NO marks will be awarded for answers in the form of flow

charts or diagrams.

TOTAL SECTION C: 40

GRAND TOTAL: 150

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