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Question
General Certificate of Education
Advanced Subsidiary Examination
June 2015
Mark
1
2
3
Human Biology
Unit 2
HBIO2
5
Humans - their origins and adaptations
Monday 1 June 2015
4
6
1.30 pm to 3.00 pm
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For this paper you must have:
 a ruler with millimetre measurements
 a calculator.
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9
10
Time allowed
 1 hour 30 minutes
TOTAL
Instructions
 Use black ink or black ball-point pen.
 Fill in the boxes at the top of this page.
 Answer all questions.
 You must answer the questions in the spaces provided. Do not write
outside the box around each page or on blank pages.
 Do all rough work in this book. Cross through any work you do not
want to be marked.
Information
 The marks for questions are shown in brackets.
 The maximum mark for this paper is 80.
 You are expected to use a calculator where appropriate.
 You will be marked on your ability to:
– use good English
– organise information clearly
– use accurate scientific terminology.
(JUN15HBIO201)
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Answer all questions in the spaces provided.
1
Figure 1 shows some cells in different stages of mitosis.
Figure 1
Y
Z
1 (a) (i)
Name stage Y and describe what is happening to the chromosomes.
[2 marks]
Name of stage Y .................................................
Description of what is happening to chromosomes.............................................................
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1 (a) (ii) Name stage Z and describe what is happening to the chromosomes.
[2 marks]
Name of stage Z .................................................
Description of what is happening to chromosomes.............................................................
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1 (b)
All the cells of the body contain the same alleles.
Explain why.
[2 marks]
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2
Archeologists have found evidence of the physical characteristics of hominids and their
cultural evolution. The evidence can be put into the following categories:





A, evidence of
B, evidence of
C, evidence of
D, evidence of
E, evidence of
upright posture
cranial capacity
diet
the use of tools
the control of fire.
Table 1 shows different types of evidence found at hominid archaeological sites.
Complete Table 1 to show into which category A to E each of the following examples of
evidence should be placed.
Each letter may be used once, more than once, or not at all. The first one has been
completed for you.
[5 marks]
Table 1
Example of evidence found
Skeletons have an S-shaped vertebral column
Category
A
Teeth have thick enamel
Animal bones have scrape marks on them
Skulls have the foramen magnum at the bottom
Stones are charred
Jaws have large canine teeth
5
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3 (a)
In humans, meiosis reduces the number of chromosomes from the diploid number to the
haploid number.
Explain why this is important.
[1 mark]
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3 (b)
Name the type of error in meiosis that leads to Down’s syndrome.
[1 mark]
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3 (c)
The diploid number of chromosomes of a normal human is 46.
Complete Table 2 to show how many chromosomes would be present in the nucleus of
the following cells.
[2 marks]
Table 2
Type of cell
Number of
chromosomes
A cell from the lining of the lungs
A sperm cell
A white blood cell from a person with Down’s syndrome
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4
Different populations of humans have evolved different adaptations. These adaptations
increased their chance of survival in the part of the world where they evolved.
4 (a) (i)
Populations of humans that evolved in hot parts of the world have large surface area to
volume ratios.
Explain the advantage of this.
[1 mark]
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4 (a) (ii) In northern countries, where the days are short during winter, populations of humans
evolved pale skins.
Explain the advantage of their pale skin.
[2 marks]
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4 (b)
Humans are also able to live at high altitude.
Suggest and explain one way in which the blood of humans who live at high altitude is
adapted to increase their chance of survival.
[2 marks]
Adaptation ...........................................................................................................................
Explanation ..........................................................................................................................
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5 (a)
What is a fossil?
[1 mark]
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5 (b)
Table 3 shows the fossil record for the evolution of Equus (the modern horse) from a
species called Hyracotherium.
Table 3
Name
Age of oldest fossils
found / years
Hyracotherium
54 million
Mesohippus
38 million
Merychippus
26 million
Pliohippus
7 million
Equus (modern horse)
1 million
Diagram
Leg bones
Use information in Table 3 to name two techniques scientists could have used to date
Hyracotherium fossils.
[2 marks]
1 ...........................................................................................................................................
2 ...........................................................................................................................................
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5 (c)
Although the full fossil record exists for the modern horse, the full fossil record does not
exist for all species.
Suggest one reason why.
[1 mark]
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5 (d)
Today, only the modern horse exists on Earth. All other species in Table 3 are extinct.
How does the theory of evolution by means of natural selection help to explain how the
other species became extinct?
[4 marks]
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6
There is evidence that the first farmers came to Europe from southwest Asia.
6 (a)
Evidence from some archaeological sites in Europe suggests that these farmers brought
cattle and cereal crops with them.
6 (a) (i)
Suggest two types of evidence that might have been found at the archaeological sites
that could show that the farmers brought cattle with them.
[2 marks]
1 ...........................................................................................................................................
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2 ...........................................................................................................................................
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6 (a) (ii) Suggest one type of evidence that might have been found at the archaeological sites
that could show that the farmers brought cereal crops with them.
[1 mark]
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6 (a) (iii) Suggest one reason why farmers brought both cattle and cereal crops with them.
[1 mark]
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6 (b)
Most of the archaeological sites where evidence of farming has been found are close to
rivers.
Suggest two reasons why farmers settled near rivers.
[2 marks]
1 ...........................................................................................................................................
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2 ...........................................................................................................................................
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6 (c)
After farmers from Asia moved into Europe, many Europeans changed their lifestyle from
hunter-gathering to farming.
Describe two consequences of this change in lifestyle.
[2 marks]
1 ...........................................................................................................................................
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2 ...........................................................................................................................................
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7
Sports scientists investigated the effect of increasing carbon dioxide concentration in
inhaled air on breathing. Table 4 shows their results.
Table 4
Percentage concentration of carbon dioxide in
inhaled air
0.03
1.00
1.50
3.00
4.50
6.00
Number of breaths per
minute
13
13
14
14
15
28
Volume of air inhaled at
each breath / cm3
660
700
800
1300
1700
2475
7 (a) (i)
Describe the effect of increasing carbon dioxide concentration on the number of breaths
taken per minute.
[2 marks]
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7 (a) (ii) Calculate the percentage increase in volume of air inhaled at each breath when the
percentage concentration of carbon dioxide in inhaled air increases from 0.03 to 6.00%.
[2 marks]
Answer ............................... %
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7 (a) (iii) Chemoreceptors detect changes in carbon dioxide concentrations in the body.
Name two parts of the body where these chemoreceptors are found.
[2 marks]
1 ...........................................................................................................................................
2 ...........................................................................................................................................
7 (b)
Describe the role of stretch receptors in the lungs in the maintenance of breathing.
[2 marks]
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8
Farmers manage hedges around their land. Biologists investigated the relationships
between:


hedge width and the number of bird species present in the hedge
hedge height and the number of bird species present in the hedge.
Figure 2 shows their findings.
Figure 2
6
Number of
bird species
4
per 100 m length
of hedge
2
0
0
2.5
5.0 7.5 10.0 12.5 15.0
Hedge width / m
0
2.5
5.0 7.5 10.0 12.5 15.0
Hedge height / m
6
Number of
bird species
per 100 m length 4
of hedge
2
0
8 (a)
A farmer who wanted to increase the number of birds on his land read about this
investigation.
He concluded that wide hedges would increase the number of birds more than high
hedges.
Do the data support this conclusion?
[3 marks]
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8 (b)
In one hedge, the biologists found two types of bird that looked similar to each other.
They wanted to determine if they were the same species. They used breeding
experiments to investigate this.
Suggest what the biologists did.
[3 marks]
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8 (c)
Other than the removal of hedges, describe and explain one way in which human
activity could reduce the size of bird populations.
[2 marks]
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8
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9
Tobacco tar in cigarettes may damage DNA and cause mutations in the genes that
control cell division. This can lead to tumour growth and lung cancer.
9 (a) (i)
Name one type of gene that can prevent tumour growth.
[1 mark]
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9 (a) (ii) Other than tobacco tar in cigarettes, name one factor that may damage DNA and cause
mutations in the genes that control cell division.
[1 mark]
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9 (b)
A chemotherapy drug is a drug used in the treatment of cancer. The drug causes cells
to die.
Researchers recruited 1059 lung cancer patients who were already taking two
chemotherapy drugs.
They divided the volunteers into two groups at random.


Group A contained 533 patients who continued to take the two chemotherapy drugs.
This was the control group.
Group B contained 526 patients who continued to take the two chemotherapy drugs
plus another chemotherapy drug called Erlotinib.
Figure 3 and Table 5 show the results of their investigation.
Figure 3
100
Key
Group A
Group B
80
60
Percentage
of patients
still alive
40
20
0
0
5
10
15
20
Number of months after treatment started
Table 5
Median survival time /
months
Percentage of patients
alive after one year
A
9.3
43.8
B
10.0
46.9
Group
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9 (b) (i)
What is meant by median survival time?
[1 mark]
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9 (b) (ii) The researchers concluded that Erlotinib combined with two other chemotherapy drugs
did not give a survival advantage over the two other chemotherapy drugs alone.
Do you agree with this conclusion? Give reasons for your answer.
[2 marks]
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9 (b) (iii) After reading about this research, a student said “smoking cigarettes should be made
illegal and NHS money should not be put into the treatment of diseases linked to
smoking.”
Discuss the moral and ethical issues raised by what the student said.
[3 marks]
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10
Read the following passage.
In 2013, the scientific world celebrated the 60th anniversary of Watson and Crick’s
1953 paper on the structure of the DNA molecule. Their paper was not an instant
success. Their suggested structure for the DNA molecule was not widely accepted
until the publishing of another paper 5 years later.
Meselson and Stahl’s experiments on the replication of DNA published in 1958
5
helped reinforce Watson and Crick’s suggested structure of the DNA molecule.
Meselson and Stahl grew bacteria in a medium containing 15N (‘heavy’ nitrogen) for
several generations. The nitrogen was incorporated into the DNA of the bacteria.
They then transferred the bacteria to a growth medium in which the nitrogen source
contained only 14N (‘light’ nitrogen). They extracted and analysed DNA from the
10
bacteria at three stages. When bacteria were grown in the 15N medium, the bacterial
DNA settled as a band near the bottom of a test tube. After one division of the
bacteria in the 14N medium, the bacterial DNA settled as a band in the middle of a test
tube. After two divisions of the bacteria in the 14N medium, two DNA bands appeared
in a test tube. They concluded the replication of DNA is semi-conservative.
15
In the 1960s, Meselson worked with scientists called Brenner and Jacob on protein
synthesis. They performed experiments with bacteria to determine the role that RNA
plays in protein synthesis.
Use information from the passage and your own knowledge to answer the questions.
10 (a)
Describe the structure of the DNA molecule that Watson and Crick suggested (line 3).
[2 marks]
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10 (b)
Into which part of the bacterial DNA was the nitrogen incorporated (line 8)?
[1 mark]
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10 (c)
Describe, in detail, what happens during the semi-conservative replication of DNA.
[6 marks]
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10 (d) (i)
Meselson and Stahl extracted and analysed DNA from the bacteria (lines 10 and 11).
DNA is easier to extract from bacteria than from eukaryotic cells.
Suggest why.
[1 mark]
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10 (d) (ii) State the property of the DNA that caused it to settle as bands at different positions in a
test tube (lines 11 to 15).
[1 mark]
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Figure 4 shows how the DNA that Meselson and Stahl extracted and analysed from the
bacteria settled in each test tube (lines 7 to 15).
After two divisions of the bacteria in the 14N medium, two DNA bands appeared in the
test tube (lines 14 to 15).
Figure 4
DNA
DNA from bacteria
grown in a 15N medium
DNA from bacteria
grown originally in a
15N medium, then
transferred for one
division to a medium
containing 14N
DNA from bacteria
after two divisions
in a 14N medium
10 (d) (iii) Complete the third test tube in Figure 4 by drawing the positions of the two DNA bands.
The position of the DNA in the first two test tubes has been completed for you.
[2 marks]
10 (d) (iv) Explain the positions of the bands you have drawn in the third tube in Figure 4.
[2 marks]
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10 (e)
In the 1960s, Meselson worked with scientists called Brenner and Jacob on protein
synthesis (lines 16 to 17).
10 (e) (i)
State the monomers that make up a protein.
[1 mark]
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10 (e) (ii) Describe the role of DNA in protein synthesis.
[3 marks]
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10 (e) (iii) Meselson, Brenner and Jacob performed experiments with bacteria to determine the role
that RNA plays in protein synthesis.
Describe the role of RNA in protein synthesis.
[1 mark]
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20
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