Download extra U4 questions

1.
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
genetically controlled. A single gene has alleles TA, TB and TC each of which codes for a
different sort of trypsin inhibitor. These alleles are codominant so plant with the genotype TATB
will produce two sorts of trypsin inhibitor, inhibitor A and inhibitor B. A fourth, recessive allele,
To does not code for a trypsin inhibitor. This information is summarised in the table.
(a)
Allele
Inhibitor produced
TA
A
TB
B
TC
C
To
None
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)
(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.
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Inhibitors present in seed
Number of seeds
A and B
23
A
25
B
48
1
(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
and
Inhibitor B
Inhibitor A
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)
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
Primary
consumers
90
80
70
60
Consumer
biomass/g m –2
50
40
30
20
Secondary
consumers
10
0
0
200
400
600
800
1000
Producers biomass/g m–2
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(d) Briefly describe how the data on the biomass of the producers might have been collected.
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................(2)
(e)
(i)
In this investigation, the efficiency with which the energy in sunlight was converted
into energy in the biomass of the producers was found to be 4%. For every 10 000 kJ
of light energy falling on the beans, 400 kJ was therefore converted into energy in
producer biomass. Use the data in the graph to complete the diagram below which
shows the amount of biomass in the primary consumers and the secondary
consumers.
Energy in sunlight
10 000 kJ
4%
Energy in producer biomass
400 kJ
......... %
Energy in primary consumer biomass.
...... kJ
......... %
Energy in secondary consumer biomass.
...... kJ
(2)
(ii) Explain why not all of the energy in producer biomass can be converted into energy
in primary consumer biomass.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................(2)
(Total 14 marks)
2.
Answers should be written in continuous prose. Credit will be given for biological accuracy; the
organisation and presentation of the information and the way in which the answer is expressed.
Read the following passage.
Photosynthesis takes place in the chloroplasts. These are disc-shaped organelles surrounded by an
outer envelope consisting of two layers of membrane. Inside, there are further membranes which
are arranged in stacks called grana. Surrounding these is the stroma. Chlorophyll and other lightcapturing pigments are found on the membranes of the grana and it is here that the
light-dependent reaction takes place. This generates the ATP and reduced NADP which are used
in the light-independent reaction in the stroma.
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(a)
(i)
Describe the way in which ATP and reduced NADP are produced in the
light-dependent reaction of photosynthesis.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................(5)
(ii) Explain how ATP and reduced NADP are used in the light-independent reaction of
photosynthesis.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................(4)
(b)
Using the information in the passage, describe how the structure of a chloroplast is adapted
to its function in photosynthesis.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................(3)
(Total 12 marks)
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3.
Hares are small mammals similar to rabbits. The diagram shows how some of the hares found in
southern Africa are classified.
Animalia
Chordata
Mammalia
Lagomorpha
Leporidae
Lepus
Pronolagus
Pronolagus
randensis
Jameson's hare
(a)
(i)
Pronolagus
rupestris
Smith's hare
Pronolagus
crassicaudatus
Natal rock hare
Lepus
capensis
Cape hare
Lepus
saxatilis
Scrub hare
Name the genus to which the scrub hare belongs.
...........................................................................................................................(1)
(ii) Name the order to which the Natal rock hare belongs.
...........................................................................................................................(1)
(b) The map shows the distribution of three of these species of hare.
Key
Jameson's hare
Smith's hare
Natal rock hare
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What is the evidence from the map that suggests that Smith’s hare and the Natal rock
hare are different species?
(i)
...........................................................................................................................
...........................................................................................................................(1)
Suggest what has caused the gene pools of the two populations of Jameson’s hare to
differ.
(ii)
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................(2)
(Total 5 marks)
4.
Moose are large herbivorous animals.
(a)
In a study of one population of moose, 72 animals were trapped and marked with ear tags.
They were then released. One month later, fieldworkers examined 120 moose and found
that 14 of these had ear tags.
Use these figures to calculate the size of the moose population. Show your working.
Answer:............................
(2)
(b)
Isle Royale is a large island in Lake Superior. Moose first colonised this island in 1900. At
the time they had no predators on the island. Wolves, which are predators of moose, were
introduced to the island in 1950. The graph shows the moose population from 1900.
Island colonised
by moose
Wolves
introduced
3000
2000
Moose
population
1000
0
1900
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1910
1920
1930
1940
Date
1950
1960
1970
6
(i)
Suggest an explanation for the changes in the moose population before the
introduction of the wolves.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................(2)
(ii) Describe the effect of introducing wolves on the moose population.
...........................................................................................................................
...........................................................................................................................(1)
(Total 5 marks)
5.
Answers should be written in continuous prose. Credit will be given for biological accuracy, the
organisation and presentation of the information and the way in which the answer is expressed.
The diagram shows part of a system designed to meet all the basic needs of a family of four living
in the tropics.
Crop plants
Crop waste
Solid waste
used as fertiliser
Urine and faeces
Fermenter
containing
bacteria
Liquid waste
Carbon
dioxide
Cattle and
chickens
Algae in
shallow pond
Fish
Gas used as fuel for
cooking and lighting
Urine and
faeces
Humans
(a)
The processes which naturally form part of the nitrogen cycle can make nitrogen contained
in urine and faeces available to crop plants. Describe how these processes occur.
.....................................................................................................................................
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.....................................................................................................................................
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.....................................................................................................................................
.....................................................................................................................................(6)
(b) Explain the advantage in this system of:
(i)
growing leguminous plants such as groundnuts or beans;
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
........................................................................................................................... (4)
(ii)
stocking the pond with fish that feed on algae rather than with carnivorous fish.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................(3)
(Total 13 marks)
6.
The island of Surtsey was formed in 1963 by a series of volcanic eruptions. Biologists have
studied the colonisation of this new island by plants and animals.
(a)
The graph shows the number of species of plants found on the island each year for the first
seven years of its existence.
16
14
12
10
Number
of species
8
6
4
2
0
1963
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1964
1965
1966
1967
Year
1968
1969
1970
8
The development of the plant community on Surtsey illustrates the process of succession. Explain
why:
(i)
very few species could grow on the island in the first few years after it was formed;
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................(1)
(ii) once some plants were growing, the rate at which new species could establish
themselves increased rapidly.
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...........................................................................................................................
...........................................................................................................................(2)
(b) Animals also colonised Surtsey. One conclusion drawn from studying them was that
particular species of animals found here had broader ecological niches than they did on the
nearby mainland. Suggest why.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................(1)
(Total 4 marks)
7.
(a)
The diagram shows an outline of the nitrogen cycle.
Nitrogen gas
in
atmosphere
Plant
protein
Animal
protein
Death and decay
in
soil
Ammonia
Nitrogen
gas
Process X
Substance A
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Process Z
9
Name:
(i)
substance A;
...........................................................................................................................
(ii)
process X;
...........................................................................................................................
(iii)
process Z.
...........................................................................................................................(3)
(b)
The table shows the yield of a crop when different levels of nitrogen fertiliser were applied.
(i)
Nitrogen fertiliser
applied/ kg hectare–1
Yield/
tonnes hectare–1
0
2.8
50
3.3
100
4.2
150
4.7
200
4.7
Describe the effect that the fertiliser had on the yield of the crop.
...........................................................................................................................
...........................................................................................................................(1)
(ii) Explain two disadvantages of applying nitrogen fertiliser at levels above 150 kg
hectare–1.
1.........................................................................................................................
...........................................................................................................................
2.........................................................................................................................
........................................................................................................................... (4)
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(c)
The graphs show the range of heights of samples of two varieties of wheat grown under the
same conditions. Variety A is a modem form and Variety B is a form that was commonly
grown 100 years ago.
200
Number
of
plants
200
150
Number
of
plants
100
50
150
100
50
0
0
50
100
Height / cm
150
Variety A
(i)
50
100
Height / cm
150
Variety B
Name the type of variation shown in these two graphs.
...........................................................................................................................(1)
(ii) Describe two differences shown in the graphs between Variety A and B.
1.........................................................................................................................
...........................................................................................................................
2.........................................................................................................................
........................................................................................................................... (2)
(iii)
Suggest how the differences between the two varieties could have been brought
about.
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........................................................................................................................... (2)
(iv) Suggest the advantages that these differences could have for modern farmers.
...........................................................................................................................
...........................................................................................................................
........................................................................................................................... (2)
Assume that two genes affect the height of wheat plants and both of these genes have two alleles.
The table gives a summary of some possible genotypes and phenotypes.
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Genotype
Phenotype
height of wheat/cm
AABB
100
AaBb
70
AAbb
70
aabb
40
A wheat plant that was 100 cm tall was crossed with a wheat plant that was 40 cm tall,
fertilisation occurred and the seeds were planted and grown.
(d)
Using only the information in the table, answer the following questions.
(i)
What are the genotypes of the gametes in this cross?
...........................................................................................................................(1)
(ii) What would be the expected genotype and phenotype of the resulting offspring?
Genotype ...........................................................................................................
Phenotype ..........................................................................................................(2)
(Total 18 marks)
Q1(a) Multiple alleles only involve one gene/one locus/polygene more than one gene:
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12
(b)
(c)
A A
A O
(i)
T T and T T ;
(ii)
T and T ;
(i)
Phenotypes of parents
(ii)
B
1
C
1
(Inhibitors) A and B
(Inhibitor) B;
A B
Genotypes of parents
T T
Genotypes of offspring
T T
A B
B O
T T ;
A O
T T
B O
B B
T T
T T :
3
Assess probability;
of results being due to chance;
or
2
Significant difference;
Between O & E/from Null hypothesis;
(d)
Random sampling/known area;
Weighing all plant material (finding dry mass of plants);
(e)
(i)
Percentage in each case is
9 – 10,
7.5 – 12.5;
Energy in each case is
36 – 40kJ
3 – 5kJ;
or
0.36  0.4%
36
(ii)
2
 40kJ
2
0.027  0.05%
2.5
 5kJ
Any two from
Lost as heat; in respiration; movement; excreted material:
egested/not all digested:
not all eaten;
2
[14]
Q2. (a) (i)
In context of ATP formation
light raises energy level of / excites electrons;
pass through carriers;
energy released;
ATP formed from ADP + P;
In context of producing reduced NADP
+
protons / H ions;
from photolysis / water;
electrons;
(ii)
(b)
max 5
GP converted to triose phosphate / GALP;
this involves reduction;
reduced NADP provides reducing power / hydrogens;
ATP supplies energy for this reaction;
phosphate from ATP;
for production of RuBP;
max 4
Membranes / (disc) shape provides large surface for light absorption;
layering of membrane allows a lot of pigment;
(permeable) membrane allows diffusion of gases / carbon dioxide;
membranes provide surface for attachment of electron / hydrogen
acceptors;
stroma / matrix containing enzymes for Calvin cycle /
light–independent reactions;
max 3
[12]
Q3. (a) (i)
(b)
Lepus; 1
(ii)
Lagomorpha;
1
(i)
Distribution / habitat overlaps / found in the same place;
1
(ii)
Geographical isolation / separation / barrier;
Adapted to slightly different conditions / environment /
different selection pressure;
Mutation in one population / different mutations;
max 2
[5]
Q4. (a) Allow two marks for 617;
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allow one mark if arithmetical error in calculation;
(b)
(i)
(ii)
2
Moose numbers rose in absence of predators / with plenty of food;
depletion of food / spread of disease / climatic change /
resulted in fall / death;
2
Caused the moose numbers to stabilise at lower level / equivalent;
1
[5]
Q5. (a) Organic compounds of nitrogen / named example;
converted to ammonium compounds / ammonia;
by saprophytes / saprobionts / decomposers / equivalent;
to nitrites;
to nitrates;
by nitrifying bacteria / named bacteria;
uptake by roots;
6
(b)
(i)
(ii)
max
Nitrogen fixing bacteria / named e.g.;
in root nodules (of legumes);
convert nitrogen to ammonium / organic compounds (in legume);
released on decomposition;
and converted to nitrates; less need for fertiliser;
max 4
Shorter food chain / less trophic levels;
will produce a greater yield of fish;
less energy lost between stages / more energy from producers;
(energy loss) in respiration / as heat;
fish prevent algal blooms / equivalent;
max 3
[13]
Q6. (a) (i)
(Few species adapted to) hostile/harsh environment/colonising bare/
volcanic/fresh rock/little/no soil/water/humus;
(ii)
(b)
Colonisers erode rock/release minerals;
add (more) humus/increase nitrate content/organic material;
when colonisers die/decompose;
More/less competition;
1
max. 2
1
[4]
Q7. (a) (i)
(b)
(c)
–
1
(ii)
Nitrification;
1
(iii)
Denitrification;
1
–1
(i)
(Increase) fertiliser increases yield up to 150 kg hectare ;
(ii)
(Excess) runs off/leaching/washed out;
eutrophication;
no extra yield;
cost (only once)/economic waste;
kills crops; due to osmotic effects/pH imbalance;
1
max. 4
(i)
Continuous;
(ii)
A has a smaller range of heights;
A is shorter/explained;
A is skewed;
(allow converse)
max. 2
Mutation;
selection;
genetic modification;
max. 2
Less stem damage in wind;
more energy used for seed formation/greater yield of seed/grain;
easier to harvest;
max. 2
(iii)
(iv)
(d)
–
Nitrate/NO 3 /nitrite/ NO 2 ;
1
(i)
AB and ab;  spaced or ringed
1
(ii)
Genotype: AaBb;
Phenotype: 70cm
2
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