1. The diagram shows a vertical section through an area of tropical rainforest in Malaysia.
50 m
P o in t A
40
30
20
10
P o in t B 0
The graph shows the daily fluctuations in carbon dioxide concentration at points A and B.
500
P o in t B
450
400
C a rb o n d io x id e
c o n c e n tr a tio n in
p a rts p e r m illio n
350
300 P o in t A
0
1200 1600 2000 0400 0800 1200 1600
M id n ig h t
T im e o f d a y
(a) (i) Explain the fluctuations in the carbon dioxide concentration which take place at
point A over a 24-hour period.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(1)
1
, (ii) At 1600 hours, the carbon dioxide concentrations at points A and B differ from
each other. Explain why.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
(b) Use information in the diagram to help explain why replacing rain forest with agricultural
crops will reduce the diversity of animals.
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
(2)
(Total 5 marks)
2. Soybeans are rich in protein. Raw soybeans, however, may contain a trypsin inhibitor. This is a
chemical which prevents the digestion of protein. The presence of this trypsin inhibitor is
A B C
genetically controlled. A single gene has alleles T , T and T each of which codes for a
different sort of trypsin inhibitor. These alleles are codominant so plant with the genotype
A B
T T will produce two sorts of trypsin inhibitor, inhibitor A and inhibitor B. A fourth,
o
recessive allele, T does not code for a trypsin inhibitor. This information is summarised in the
table.
Allele Inhibitor produced
A A
T
B B
T
C C
T
o None
T
(a) The inheritance of trypsin inhibitors in soybeans is an example of multiple allele
inheritance. Explain how multiple allele inheritance differs from polygenic inheritance.
...................................................................................................................................
...................................................................................................................................
(1)
(b) (i) Give all the possible genotypes of a plant which only contains inhibitor A.
...........................................................................................................................
(1)
2
, (ii) Give all the possible genotypes of the gametes produced by a plant which contains
inhibitors B and C.
...........................................................................................................................
(1)
(c) Two soybean plants were crossed and the seeds collected and counted. The results are
shown in the table.
Inhibitors present in seed Number of seeds
A and B 23
A 25
B 48
(i) Complete the genetic diagram to explain the results of this cross.
Phenotypes of parents:.................................. .......................................
Genotypes of parents:.................................. .......................................
Genotypes of gametes ......................................................................................
Genotypes of offspring: ....................................................................................
Phenotypes of offspring Inhibitor A Inhibitor A Inhibitor B
and
Inhibitor B
(3)
(ii) A chi-squared test was applied to the data collected in this investigation. Explain
why statistical tests such as the Chi-squared test should be carried out on data like
these.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
3
, An investigation was carried out on the insects living on bean crops. The graph shows the
relationship between the biomass of primary consumers, secondary consumers and producers.
100
90 P rim a ry
co n su m e rs
80
70
C onsum er 60
–2
b io m a s s /g m
50
40
30
20
10 S e c o n d a ry
c o n su m e rs
0
0 200 400 600 800 1000
–2
P ro d u c e r s b io m a s s /g m
(d) Briefly describe how the data on the biomass of the producers might have been collected.
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
(2)
4
50 m
P o in t A
40
30
20
10
P o in t B 0
The graph shows the daily fluctuations in carbon dioxide concentration at points A and B.
500
P o in t B
450
400
C a rb o n d io x id e
c o n c e n tr a tio n in
p a rts p e r m illio n
350
300 P o in t A
0
1200 1600 2000 0400 0800 1200 1600
M id n ig h t
T im e o f d a y
(a) (i) Explain the fluctuations in the carbon dioxide concentration which take place at
point A over a 24-hour period.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(1)
1
, (ii) At 1600 hours, the carbon dioxide concentrations at points A and B differ from
each other. Explain why.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
(b) Use information in the diagram to help explain why replacing rain forest with agricultural
crops will reduce the diversity of animals.
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
(2)
(Total 5 marks)
2. Soybeans are rich in protein. Raw soybeans, however, may contain a trypsin inhibitor. This is a
chemical which prevents the digestion of protein. The presence of this trypsin inhibitor is
A B C
genetically controlled. A single gene has alleles T , T and T each of which codes for a
different sort of trypsin inhibitor. These alleles are codominant so plant with the genotype
A B
T T will produce two sorts of trypsin inhibitor, inhibitor A and inhibitor B. A fourth,
o
recessive allele, T does not code for a trypsin inhibitor. This information is summarised in the
table.
Allele Inhibitor produced
A A
T
B B
T
C C
T
o None
T
(a) The inheritance of trypsin inhibitors in soybeans is an example of multiple allele
inheritance. Explain how multiple allele inheritance differs from polygenic inheritance.
...................................................................................................................................
...................................................................................................................................
(1)
(b) (i) Give all the possible genotypes of a plant which only contains inhibitor A.
...........................................................................................................................
(1)
2
, (ii) Give all the possible genotypes of the gametes produced by a plant which contains
inhibitors B and C.
...........................................................................................................................
(1)
(c) Two soybean plants were crossed and the seeds collected and counted. The results are
shown in the table.
Inhibitors present in seed Number of seeds
A and B 23
A 25
B 48
(i) Complete the genetic diagram to explain the results of this cross.
Phenotypes of parents:.................................. .......................................
Genotypes of parents:.................................. .......................................
Genotypes of gametes ......................................................................................
Genotypes of offspring: ....................................................................................
Phenotypes of offspring Inhibitor A Inhibitor A Inhibitor B
and
Inhibitor B
(3)
(ii) A chi-squared test was applied to the data collected in this investigation. Explain
why statistical tests such as the Chi-squared test should be carried out on data like
these.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
3
, An investigation was carried out on the insects living on bean crops. The graph shows the
relationship between the biomass of primary consumers, secondary consumers and producers.
100
90 P rim a ry
co n su m e rs
80
70
C onsum er 60
–2
b io m a s s /g m
50
40
30
20
10 S e c o n d a ry
c o n su m e rs
0
0 200 400 600 800 1000
–2
P ro d u c e r s b io m a s s /g m
(d) Briefly describe how the data on the biomass of the producers might have been collected.
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
(2)
4
