Edexcel A-LEVEL BIO5 January 2007 QP
Edexcel A-LEVEL BIO5 January 2007 QP
Edexcel A-LEVEL BIO5 January 2007 QP
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Candidate
No. 6 1 0 5 0 1
Paper Reference(s)
Biology
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Unit 5B 1
Wednesday 24 January 2007 – Morning 2
Instructions to Candidates
In the boxes above, write your centre number, candidate number, your surname, initial(s) and signature.
Check that you have the correct question paper.
Answer ALL SEVEN questions in the spaces provided in this booklet.
Show all the steps in any calculations and state the units. Calculators may be used.
Include diagrams in your answers where these are helpful.
Advice to Candidates
You will be assessed on your ability to organise and present information, ideas, descriptions and
arguments clearly and logically, taking account of your use of grammar, punctuation and spelling.
The Synoptic section (Questions 4 to 7) is designed to give you the opportunity to make connections
between different areas of biology and to use skills and ideas developed throughout the course in new
contexts. You should include in your answers any relevant information from the whole of your course.
Total
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Answer ALL questions in the spaces provided.
1. The table below refers to plant growth substances and their functions. Complete the table
by inserting the correct word or words in the spaces provided.
Gibberellin
Cytokinin
Ethene
Q1
(Total 5 marks)
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2. The diagram below shows a pair of homologous chromosomes (a bivalent) during
meiosis.
A
B
(a) (i) Name one stage of meiosis during which homologous chromosomes might look
like the ones shown in the diagram.
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(1)
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(2)
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(b) Guinea pigs are popular pets that have variations in both the colour and texture of
their fur. The allele for black fur (B) is dominant to the allele for white fur (b). The
allele for rough fur (R) is dominant to the allele for smooth fur (r).
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(1)
The phenotypes present in the F2 generation are shown below. Give the expected
ratio of the different phenotypes in the F2 generation by writing appropriate
numbers in the spaces below.
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(iii) The numbers of the different phenotypes in the offspring in the F2 generation
produced as a result of interbreeding are given in the table below.
Phenotypes Number
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(4) Q2
(Total 9 marks)
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3. (a) (i) In the space below, draw a low power plan of a cross-section through a typical
dicotyledonous leaf, to show the distribution of the tissues. On your plan label
the palisade mesophyll, the spongy mesophyll and the lower epidermis. Do not
include any cells.
(5)
(ii) Explain the role, in the process of photosynthesis, of each of the tissues you have
labelled in (a)(i).
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(b) Plants that live in shady areas have leaves that are adapted to growing in low light
intensity. Suggest how the structure of one of these leaves might differ from the leaf
that you have drawn in (a)(i).
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(2) Q3
(Total 10 marks)
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Synoptic Section
The questions in this section are designed to give you the opportunity to make connections
between different areas of biology and to use skills and ideas developed throughout the course
in new contexts. You should include in your answers any relevant information from the whole
of your course.
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B ..................................................................................
(1)
Molecule C: ............................................................................................................
Role .........................................................................................................................
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(b) Cell surface membranes can fragment forming small pieces. These small pieces curl
in on themselves to form membrane-bound vesicles filled with liquid.
The procedure was repeated with ATP added to the sodium chloride solution. The
results of this experiment are shown in the graph below.
6± With
ATP
5±
Concentration 4 ±
of sodium ions
inside the 3±
vesicles
/ arbitrary
units 2±
1±
Without
0± ATP
±
±
0 1 2 3 4 5
Time / minutes
(i) Using the information in the graph, suggest how sodium ions are transported
across the cell surface membrane into the liquid in the vesicles.
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(4)
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(ii) The loop of Henlé is part of a renal (kidney) nephron. Explain the role of
sodium and chloride ion transport in the loop of Henlé.
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(4) Q4
(Total 11 marks)
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5. The water flea, Daphnia, is a type of aquatic invertebrate found in fresh water. An
investigation was carried out to determine the effect of different concentrations of caffeine
on the heart rate of Daphnia. After being kept at a temperature of 25 °C, individual
Daphnia were placed on microscope slides in a few drops of caffeine solution. After one
minute, the heart rate of each Daphnia was counted. This procedure was repeated ten
times for each concentration of caffeine to obtain a mean heart rate. The results are shown
in the table below.
(a) (i) Describe the relationship between mean heart rate and caffeine concentration.
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(ii) Calculate the percentage increase in the mean heart rate between the control and
the solution containing 1000 parts per million of caffeine. Show your working.
Answer .................................... %
(2)
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(1)
(c) Explain why Daphnia were kept at a constant temperature throughout the
investigation.
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(d) Nicotine is another drug that will change the heart rate. Describe the effect of nicotine
on a synapse.
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(2) Q5
(Total 11 marks)
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6. The diagram below shows a summary of the breakdown of starch in the human digestive
system.
(a) Identify disaccharide X and explain how it is converted into glucose in the ileum.
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(b) Describe three features of the ileum which enable it to absorb glucose efficiently.
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(c) After a high carbohydrate meal, the blood glucose level changes. Explain how the
blood glucose level is regulated.
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(6) Q6
(Total 12 marks)
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7. An area of abandoned grassland was studied over a period of more than 100 years. During
that time, there were changes to the plant communities which resulted in changes to the
number of species and population density of small birds. The table below shows the
changes.
(a) State the name that is given to the process by which communities change over time.
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(1)
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(b) Describe the effect of the change in the plant community on the number of species of
small birds. Give reasons for your answer.
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(5)
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(c) The population density of birds drops when shrubs are replaced by pine trees, but then
increases with the change to mixed woodland. Suggest reasons for these changes in
population density.
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(d) The mixed woodland is the final climax community. Describe and explain two ways
in which woodland can be damaged by human activities.
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(4) Q7
(Total 12 marks)
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