Centre Number
Candidate Number
Candidate Name
NAMIBIA SENIOR SECONDARY CERTIFICATE
BIOLOGY HIGHER LEVEL
8321/2
PAPER 2
2 hours 15 minutes
Marks 100
2013
No Additional Materials are required.
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INSTRUCTIONS AND INFORMATION TO CANDIDATES
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Candidates answer on the Question Paper in the spaces provided.
Write your Centre Number, Candidate Number and Name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use a soft pencil for any rough work, diagrams or graphs.
Do not use correction fluid.
You may use a non-programmable calculator.
Do not write in the margin For Examiner’s Use.
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Section A
Answer all questions.
You are advised to spend no longer than 1 hour on Section A.
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Section B
For Examiner’s Use
Section A
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Answer two questions.
Write your answers on the answer sheets provided at the back of
the booklet.
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The number of marks is given in brackets [ ] at the end of each
Question.............
question or part question.
Section B
Question.............
Total
Marker
Checker
110215
This document consists of 19 printed pages and 1 blank page.
Republic of Namibia
MINISTRY OF EDUCATION
© MoE/DNEA
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SECTION A
Answer all the questions from this section in the spaces provided.
1
Fig. 1.1 is a drawing made from an electron micrograph of a longitudinal section
of a capillary in muscle tissue.
A
B
Fig. 1.1
(a) Cell A ingests and digests pathogens.
(i) State the name of this cell.
............................................................................................................ [1]
(ii) With reference to Fig.1.1, suggest how cell A is able to leave the capillary
and fight infections in the muscle tissue.
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(iii) Describe how this cell ingests and digests the pathogens.
............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ [4]
(b) Cell B is a red blood cell.
Explain how the shape of this cell helps it to absorb a large amount of oxygen.
................................................................................................................... ................................................................................................................... ................................................................................................................... ................................................................................................................... ................................................................................................................... ................................................................................................................... [3]
(c) Explain how oxygen and glucose move from the blood inside the capillary to
the tissue fluid in the muscle.
oxygen....................................................................................................... ................................................................................................................... ................................................................................................................... glucose......................................................................................................
................................................................................................................... ................................................................................................................... [4]
[14]
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Fig. 2.1 shows Amoeba proteus, which is a unicellular organism that lives in
fresh water. It has a contractile vacuole which pumps out excess water which
has entered from the environment. The contraction rate of the vacuole depends
on the salt concentration of the water in which it lives.
nucleus
contractile vacuole
Fig. 2.1
(a) (i) Name the process by which water enters A. proteus.
............................................................................................................ [1]
(ii) The diffusion of water in and out of cells depends on the water potential
gradient between the cell and its environment.
Explain why water moves into A. proteus.
............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ [2]
(iii) Suggest why the contraction of the vacuole stops when there is no
oxygen in the water.
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(b) A student set up an experiment to find out how the contraction rate of the
vacuole varied with the salt concentration of the water surrounding A. proteus.
Fig. 2.2 is a graph showing the results of the experiment.
35
30 X
X
25
number of
contractions/
min
X
X
20
X
15
X
X
10
X
5
0
X
X
0
1
2
3
4
X
5
6
percentage concentration of salt solution
Fig. 2.2
(i) With reference to Fig. 2.2, describe the effect of salt concentration on
the number of contractions.
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(ii) Suggest and explain what would happen if the concentration of the
solution increased to more than 5% .
............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ [2]
(c) Valonia is a unicellular organism which lives in sea water. It has a cell
wall and a vacuole like a plant cell. The ion concentrations in the vacuole
of Valonia were analysed and compared to the ion concentrations of the
surrounding sea water in Table 2.1.
Table 2.1
ion
concentration (mol/cm3)
sea
water
vacuole of Valonia
potassium
0.012
0.60
sodium
0.498
0.09
calcium
0.012
0.0017
chloride
0.580
0.597
(i) Calculate the ratio of the potassium ion concentration in sea water to
the potassium ion concentration in Valonia. Show your working.
Ratio………………………………..
[2]
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(ii) With reference to your answer to (i), state the process by which
potassium enters Valonia and explain your choice.
............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ [2]
(iii) Describe the process named in (ii).
............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ [4]
(iv) Suggest what would happen to Valonia if it were placed into fresh water.
............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ [3]
[20]
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Fig. 3.1 shows how the ovary and the uterus are changed by various hormones
during the menstrual cycle.
pituitary
W
ovary X
B
A
oestrogen
Z
lining of uterus
Fig. 3.1
(a) (i) Name structures A and B.
A......................................................................................................... B......................................................................................................... [1]
(ii) Name hormone W and describe its function.
Name.................................................................................................. Function..............................................................................................
............................................................................................................ ............................................................................................................ ............................................................................................................ [2]
(iii) All the undeveloped ova in the ovary of a woman are diploid primary
oocytes.
At which stage of development is the ovum in structure A?
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(b) (i) Name hormone X and explain its functions with reference to Fig. 3.1.
Name.................................................................................................. Function.............................................................................................. ............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ [3]
(ii) With reference to Fig. 3.1, name hormone Z and outline how it helps
to control the menstrual cycle.
Name.................................................................................................. Outline................................................................................................. ............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ [4]
[11]
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The element nitrogen is very important for the formation of many biological
molecules, such as amino acids and proteins.
Fig. 4.1 shows part of the nitrogen cycle.
nitrogen (N) in
the atmosphere
B
A
nitrate ions
in the soil
nitrite ions
in the soil
C
D
ammonium ions in
the soil
amino acids
in plants
urea in urine
urea
E
proteins
in plants
F
amino acids
in animals
G
proteins in
animal
Fig. 4.1
(a) Name one other biological molecule which contains nitrogen.
................................................................................................................... [1]
(b) (i) Name the process taking place at B.
............................................................................................................ [1]
(ii) Name the type of bacteria responsible for the process at C.
............................................................................................................ [1]
(c) (i) Amino acids are changed to proteins in plants and animals.
Name the part of the cell where this process occurs.
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(ii) Name and describe the biological process taking place at A.
............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ [4]
(d) (i) Process E takes place inside animals. Name this process.
............................................................................................................ [1]
(ii) State where the process named in (i) takes place and describe the
process.
............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ ............................................................................................................ [3]
(e) Describe three ways in which farmers can maintain soil fertility without using
artificially produced fertilizers.
1................................................................................................................. ................................................................................................................... 2................................................................................................................. ................................................................................................................... 3................................................................................................................. ................................................................................................................... [3]
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SECTION B
Answer any two questions from this section.
Write your answer on the answer sheets provided at the back of the booklet.
Use labelled or annotated diagrams if it will make your answer more clearly understood.
5 (a) Compare wind- and insect-pollinated flowers referring to the importance of each feature.
[7]
(b) Explain how abscisic acid and giberellins affect the germination of seeds in dry areas, such as Namibia.
[7]
(c) Explain why water, oxygen and a suitable temperature are necessary for
germination of seeds.
[6]
[20]
6
(a) Describe and explain how the body of a human responds when it moves from a warm room into the open on a very cold day.
(b) Explain with named examples, how different surface areas and body coverings influence the rate of cooling of a warm body.
[12]
[8]
[20]
7 (a) Draw and label a simple diagram to show the structure of how DNA is constructed from sugars, phosphates and bases.
[8]
(b) Compare the following terms:
(i) genotype and phenotype.
(ii) homozygous and heterozygous. [4]
(c) IA, IB, and IO are the alleles of the gene which controls human blood groups.
Draw a genetic diagram to show the possible blood groups amongst the offspring of a father, who is heterozygous for blood group A, and a mother, who is heterozygous for blood group B.
Identify the offspring with the blood group that is the result of codominance, and define codominance. [8]
[20]
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8
(a) Explain the role of photosynthesis and cellular respiration in food chains.
(b) Compare anaerobic and aerobic respiration in plants and animals.
[5]
(c) Outline the different ways in which the rate of photosynthesis could be measured.
[5]
[10]
[20]
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