IGCSE London 4325 - 2H
IGCSE London 4325 - 2H
IGCSE London 4325 - 2H
Centre
Paper Reference
No.
Signature
Candidate
No. 4 3 2 5 2 H
Paper Reference(s)
Biology
Paper 2H Question Leave
Number Blank
Higher Tier 1
2
Thursday 8 November 2007 – Morning
3
Time: 2 hours
4
5
Materials required for examination Items included with question papers 6
Nil Nil
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8
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Instructions to Candidates
In the boxes above, write your centre number, candidate number, your surname, initial(s) and 10
signature.
The paper reference is shown at the top of this page. Check that you have the correct question paper. 11
Answer ALL the questions in the spaces provided in this question paper.
Show all the steps in any calculations and state the units. 12
Calculators may be used.
13
Information for Candidates 14
The total mark for this paper is 120. The marks for parts of questions are shown in round brackets: 15
e.g. (2).
There are 28 pages in this question paper. All blank pages are indicated. 16
Advice to Candidates
Write your answers neatly and in good English.
Total
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Answer ALL the questions. Write your answers in the spaces provided.
1. Living organisms have certain characteristics in common. The table gives descriptions of
some of these characteristics.
Characteristic Description
excreting
reproducing
Q1
(Total 4 marks)
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2. (a) Substances move into and out of cells by different methods.
Complete the table by putting the correct letter for each method.
diffusion
osmosis
active transport
(3)
(b) Complete the sentences below by writing a correct word or phrase in the blank
spaces.
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(2)
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(2)
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(c) The graphs show the effect of changing the temperature on the rate of movement of
substances into cells.
rate rate
temperature temperature
A B
rate rate
temperature temperature
C D
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(1)
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(1) Q2
(Total 11 marks)
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3. A habitat is a place where organisms live. The food chains below are from different
habitats.
From a seashore
seaweed → periwinkle → oystercatcher
(a mollusc) (a bird)
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(1)
(ii) What is the original energy source for these food chains?
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(1)
Other than the names of the organisms, give two ways in which these food chains
differ from the examples in part (a).
1 ....................................................................................................................................
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2 ....................................................................................................................................
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(2)
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(c) (i) Name two groups of organisms that can act as decomposers in food chains.
1 .............................................................................................................................
2 .............................................................................................................................
(2)
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(3) Q3
(Total 9 marks)
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4. The diagram shows a section of the human eye.
cornea
retina
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(1)
(b) Some people have a rare genetic condition that makes the cornea become cloudy. As
a result they find it difficult to see clearly and may become blind.
(i) Suggest why a cloudy cornea makes it difficult for a person to see clearly.
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(2)
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(ii) The condition for cloudy cornea is caused by a dominant allele N. The recessive
allele, n, results in a clear cornea.
A couple plan to have children. The father is heterozygous for cloudy cornea and
the mother is homozygous recessive.
Complete the genetic diagram to show the genotypes of the parents, the gametes
and the possible genotypes and phenotypes of their children. Use N for the
dominant allele and n for the recessive allele.
Father Mother
Gametes
Genotypes of children
Phenotypes of children
(4) Q4
(Total 7 marks)
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5. The diagram shows a white blood cell ingesting a bacterium.
bacterium
B
(a) Complete the table to give the names and functions of the parts labelled A, B and C.
(6)
(b) Describe what happens to the bacterium after it has been ingested by the white blood
cell.
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(2)
(c) Normal blood contains 7000 white blood cells per mm3. A person with a mild
infection had blood with 10 500 white blood cells per mm3. Calculate the percentage
increase in white blood cells. Show your working.
Answer ..........................................
(2) Q5
(Total 10 marks)
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6. The technique of selective breeding can be used to produce a crop of tomato plants that
flower early.
The table shows the steps taken to breed early-flowering tomato plants.
Complete the table by using numbers to show the correct order of the steps.
(Total 4 marks)
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7. Explain how growing crops in glasshouses can alter the yield of a crop.
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(Total 5 marks)
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8. Some large molecules are made from smaller basic units.
(a) The table shows some important large molecules in living organisms. Complete the
table to show the missing large molecule and the smaller basic units.
starch
protein
(3)
(b) Protein is broken down into its smaller units by a protease enzyme. The graph shows
how the activity of a protease is affected by temperature.
rate of
reaction
in arbitrary
units
0 10 20 30 40 50 60
temperature in °C
Describe how the rate of reaction of this protease varies with temperature.
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(2) Q8
(Total 5 marks)
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9. The diagram shows part of the human digestive system.
(a) On the diagram, use an arrow and the letter L to show the large intestine.
(1)
(b) On the diagram, use an arrow and the letter B to show where bile is made.
(1)
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(d) The products of digestion are absorbed by villi in the small intestine. Explain how
the structure of villi helps absorption of these products.
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(2) Q9
(Total 6 marks)
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10. The diagram shows a nephron from a human kidney.
B
glomerulus
A .............................................................................................................................
B .............................................................................................................................
C ............................................................................................................................
(3)
(ii) Ultrafiltration occurs between the glomerulus and part A. Explain what is meant
by the term ultrafiltration.
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(b) The table shows the concentrations of urea in part A and in part C.
in part A in part C
0.03 2.00
(i) How many times more concentrated is the urea in part C compared with
part A?
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(1)
(ii) Suggest why the concentration of urea is greater in part C than in part A.
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(1)
(c) Some substances affect the secretion of ADH. These substances increase the
production of urine and are known as diuretics. Suggest how diuretics increase the
production of urine.
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(3) Q10
(Total 10 marks)
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11. The diagram shows how the levels of oestrogen and progesterone vary in the menstrual
cycle.
progesterone
hormone
levels
oestrogen
0 14 28
day of cycle
(a) On the diagram, show how the line for progesterone would change if the woman
became pregnant.
(1)
The fusion of a male and female gamete is known as fertilisation, which produces
a single cell called a ......................................... This cell divides and develops into
the uterus.
(3)
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(1) Q11
(Total 5 marks)
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12. Many scientists from the British Antarctic Survey work in the Antarctic. Sometimes the
temperature can fall as low as –50 °C. Scientists who live there need lots of energy to
work under such cold conditions.
(a) Name the process that releases energy in the cells of these scientists working in the
Antarctic.
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(1)
(b) Complete the balanced chemical equation for the process that releases energy.
(c) Explain why the scientists need lots of energy to work in these cold conditions.
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(2)
(d) Describe and explain one way in which the skin helps in temperature regulation in
cold conditions.
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(2) Q12
(Total 7 marks)
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13. The diagram shows some of the processes in the nitrogen cycle.
dead organic
material
A
B
nitrogen gas
C
D nitrate nitrite
(a) Give the letter of one stage that involves each of the following.
(b) Fungi are also involved in the nitrogen cycle. Describe how fungi feed.
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(2)
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(c) Explain how the use of nitrate fertiliser on a farmer’s field can affect algal growth in
rivers.
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(4) Q13
(Total 9 marks)
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14. Cauliflowers are vegetables. They may be grown by micropropagation. Small pieces of
plant (explants) are grown on nutrient jelly. The young plants are then transferred into
growing trays. The technique produces clones. The process is shown in the diagram.
explant
young plant
growing tray
parent
cauliflower nutrient
jelly
(a) Explain why the young cauliflower plants are described as clones.
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(2)
(b) Give one advantage and one disadvantage to the grower of producing new cauliflower
plants that are clones.
Advantage .....................................................................................................................
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Disadvantage ................................................................................................................
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(2)
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(c) Scientists have produced transgenic animals. These animals can also be cloned.
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(2)
Use 1 ......................................................................................................................
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Use 2 ......................................................................................................................
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(4) Q14
(Total 10 marks)
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15. (a) The diagram shows a section through the left side of the heart as seen from the front.
The black arrows indicate the direction of blood flow.
(i) On the diagram, use an arrow and the letter A to show the left atrium.
(1)
(ii) Give two features of the diagram which show that the ventricle is contracting.
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2 .............................................................................................................................
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(2)
(iii) Name the vessel through which blood enters the left side of the heart.
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(1)
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(b) When a part of the heart contracts, the blood pressure in that part increases.
When the part relaxes, the blood pressure in that part decreases.
The table shows the changes in blood pressure in the left atrium, the left ventricle
and the aorta at different times during a sequence of contraction and relaxation of the
heart.
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(1)
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(1)
(iii) At which time does blood start flowing into the aorta? Explain your answer.
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(3) Q15
(Total 9 marks)
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16. Cystic fibrosis is a condition that affects the lungs.
(a) People with cystic fibrosis have mucus in the air passages of their lungs that is thicker
and stickier than normal.
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(b) Cystic fibrosis is an inherited condition. Attempts have been made to treat people
with cystic fibrosis by transferring normal genes into lung cells with defective genes.
This is an example of genetic modification.
Describe how a gene can be transferred from one organism to another using genetic
modification.
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(6) Q16
(Total 9 marks)
TOTAL FOR PAPER: 120 MARKS
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