Please check the examination details below before entering your candidate information
Candidate surname Other names
Centre Number Candidate Number
Pearson Edexcel Level 3 GCE
Wednesday 19 June 2024
reference 9BN0/03
Biology A (Salters Nuffield)
Advanced
Total Marks
of the scientific article adapted from the New Scientist and the
Brazilian Journal of Medical and Biological Research (enclosed)
Instructions
• Use black ink or ball-point pen.
centre number and candidate number.
• Show all your working out in calculations and include units where appropriate.
Answer the questions in the spaces provided
– there may be more space than you need.
Information
• The total mark for this paper is 100.
The marks for each question are shown in brackets
– use this as a guide as to how much time to spend on each question.
In questions marked with an asterisk (*), marks will be awarded for your ability to structure your
answer logically, showing how the points that you make are related or follow on from each other
where appropriate.
Advice
• Read each question carefully before you start to answer it.
• Check your answers if you have time at the end. Turn over
, Answer ALL questions.
Write your answers in the spaces provided.
1 One of the first plant species to colonise some habitats is thale cress
(Arabidopsis thaliana).
The plant hormone IAA (auxin) is produced in the growing tips of plants such as thale cress.
(Source: Nigel Cattlin / Alamy Stock Photo)
(a) State what is meant by the term colonisation of a habitat.
(1)
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............................................................................................................................. .. ................................................................................................... ............................ ......................
............................................................................................................................. .. ....................................................................... ........................................................ ......................
2
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, (b) One role of IAA is to stimulate the phototropic response of shoots.
Describe how IAA causes a phototropic response in the shoots of a plant.
(3)
............................................................................................................................. .. ..................................................................................... .......................................... ......................
............................................................................................................................. .. ............................................................................................................................. .. ......................
............................................................................................................................. .. ............................................................................................................................. .. ......................
............................................................................................................................. .. ................................................................................................... ............................ ......................
............................................................................................................................. .. ....................................................................... ........................................................ ......................
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............................................................................................................................. .. ............................................................................................................................... ......................
............................................................................................................................. .. ............................................................................................................................. .. ......................
............................................................................................................................. .. ................................................................................................... ............................ ......................
(c) Another role of IAA is to stimulate the growth of lateral roots. The
diagram shows the roots of thale cress.
lateral roots
main root
3
■■■■ Turn over
, One type of receptor for IAA is coded for by the tir1 gene.
Scientists have investigated the effect of IAA on the growth of lateral roots in thale
cress.
Plants homozygous for a normal tir1 gene and plants homozygous for a mutation in the
tir1 gene were used in this investigation.
The plants were treated with different concentrations of IAA.
The mean number of lateral roots produced per mm of main root was recorded. The
graph shows the results of this investigation.
Key
1.6 Thale cress
1.4 homozygous for:
1.2 normal
Mean number of 1.0 tir1 gene
lateral roots per mm
0.8 mutant
tir1 gene
0.6
0.4
0.2
0.0 0.00 0.01 0.10 1.00
IAA concentration / μmol dm–3
(i) Explain why the scientists used plants homozygous for the normal and the mutant
tir1 gene in this investigation.
(2)
............................................................................................................................. .. ........................................................................................... .................................... ......................
............................................................................................................................. .. ............................................................................................................................. .. ......................
............................................................................................................................. .. ............................................................................................................................. .. ......................
............................................................................................................................. .. ................................................................................................... ............................ ......................
............................................................................................................................. .. ....................................................................... ........................................................ ......................
............................................................................................................................. .. ........................................... .................................................................................... ......................
4
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Candidate surname Other names
Centre Number Candidate Number
Pearson Edexcel Level 3 GCE
Wednesday 19 June 2024
reference 9BN0/03
Biology A (Salters Nuffield)
Advanced
Total Marks
of the scientific article adapted from the New Scientist and the
Brazilian Journal of Medical and Biological Research (enclosed)
Instructions
• Use black ink or ball-point pen.
centre number and candidate number.
• Show all your working out in calculations and include units where appropriate.
Answer the questions in the spaces provided
– there may be more space than you need.
Information
• The total mark for this paper is 100.
The marks for each question are shown in brackets
– use this as a guide as to how much time to spend on each question.
In questions marked with an asterisk (*), marks will be awarded for your ability to structure your
answer logically, showing how the points that you make are related or follow on from each other
where appropriate.
Advice
• Read each question carefully before you start to answer it.
• Check your answers if you have time at the end. Turn over
, Answer ALL questions.
Write your answers in the spaces provided.
1 One of the first plant species to colonise some habitats is thale cress
(Arabidopsis thaliana).
The plant hormone IAA (auxin) is produced in the growing tips of plants such as thale cress.
(Source: Nigel Cattlin / Alamy Stock Photo)
(a) State what is meant by the term colonisation of a habitat.
(1)
............................................................................................................................. .. ............................................................................................................................. .. ......................
............................................................................................................................. .. ................................................................................................... ............................ ......................
............................................................................................................................. .. ....................................................................... ........................................................ ......................
2
■■■■
, (b) One role of IAA is to stimulate the phototropic response of shoots.
Describe how IAA causes a phototropic response in the shoots of a plant.
(3)
............................................................................................................................. .. ..................................................................................... .......................................... ......................
............................................................................................................................. .. ............................................................................................................................. .. ......................
............................................................................................................................. .. ............................................................................................................................. .. ......................
............................................................................................................................. .. ................................................................................................... ............................ ......................
............................................................................................................................. .. ....................................................................... ........................................................ ......................
............................................................................................................................. .. ........................................... .................................................................................... ......................
............................................................................................................................. .. ............................................................................................................................... ......................
............................................................................................................................. .. ............................................................................................................................. .. ......................
............................................................................................................................. .. ................................................................................................... ............................ ......................
(c) Another role of IAA is to stimulate the growth of lateral roots. The
diagram shows the roots of thale cress.
lateral roots
main root
3
■■■■ Turn over
, One type of receptor for IAA is coded for by the tir1 gene.
Scientists have investigated the effect of IAA on the growth of lateral roots in thale
cress.
Plants homozygous for a normal tir1 gene and plants homozygous for a mutation in the
tir1 gene were used in this investigation.
The plants were treated with different concentrations of IAA.
The mean number of lateral roots produced per mm of main root was recorded. The
graph shows the results of this investigation.
Key
1.6 Thale cress
1.4 homozygous for:
1.2 normal
Mean number of 1.0 tir1 gene
lateral roots per mm
0.8 mutant
tir1 gene
0.6
0.4
0.2
0.0 0.00 0.01 0.10 1.00
IAA concentration / μmol dm–3
(i) Explain why the scientists used plants homozygous for the normal and the mutant
tir1 gene in this investigation.
(2)
............................................................................................................................. .. ........................................................................................... .................................... ......................
............................................................................................................................. .. ............................................................................................................................. .. ......................
............................................................................................................................. .. ............................................................................................................................. .. ......................
............................................................................................................................. .. ................................................................................................... ............................ ......................
............................................................................................................................. .. ....................................................................... ........................................................ ......................
............................................................................................................................. .. ........................................... .................................................................................... ......................
4
■■■■
