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1. Explain the process of aerobic cellular respiration. 2. At the start of

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1.
Explain the process of aerobic cellular respiration.
(Total 8 marks)
2.
At the start of glycolysis, glucose is phosphorylated to produce glucose 6-phosphate, which is
converted into fructose 6-phosphate. A second phosphorylation reaction is then carried out, in
which fructose 6-phosphate is converted into fructose 1,6-bisphosphate. This reaction is
catalyzed by the enzyme phosphofructokinase. Biochemists measured the enzyme activity of
phosphofructokinase (the rate at which it catalyzed the reaction) at different concentrations of
fructose 6-phosphate. The enzyme activity was measured with a low concentration of ATP and
a high concentration of ATP in the reaction mixture. The graph below shows the results.
Low ATP concentration
Enzyme activity
High ATP concentration
Fructose 6-phosphate concentration
(a)
(i)
Using only the data in the above graph, outline the effect of increasing fructose
6-phosphate concentration on the activity of phosphofructokinase, at a low ATP
concentration.
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(2)
1
(ii)
Explain how increases in fructose 6-phosphate concentration affect the activity of
the enzyme.
...........................................................................................................................
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...........................................................................................................................
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(2)
(b)
(i)
Outline the effect of increasing the ATP concentration on the activity of
phosphofructokinase.
...........................................................................................................................
...........................................................................................................................
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(2)
(ii)
Suggest an advantage to living organisms of the effect of ATP on
phosphofructokinase.
...........................................................................................................................
...........................................................................................................................
(1)
(Total 7 marks)
2
3.
Up to two additional marks are available for the construction of your answers.
(2)
(a)
Draw and label a mitochondrion as seen in electron micrographs.
(4)
(b)
Outline the cellular locations of different named processes in both photosynthesis and
cell respiration.
(6)
(c)
Explain the energy flow in a food chain as exemplified by a pyramid of energy.
(8)
(Total 20 marks)
4.
The respiratory quotient (RQ) is a measure of the metabolic activity of an animal. It is the ratio
of CO2 produced to O2 consumed. In general, the lower the RQ value the higher the energy
yield. The RQ is dependent on the diet consumed by the animal. The following table lists the
typical RQ values for specified diets.
Diet
RQ
Lipid
0.71
Carbohydrate
1.00
Protein
0.74
[Source: Walsberg and Wolf, Journal of Experimental Biology, (1995), 198, pages 213–219.
Reproduced by permission of The Company of Biologists Ltd]
In an experiment to assess RQ values for house sparrows, the birds were fed a diet of pure
mealworms (beetle larvae) or millet (a type of grain).
3
The graph below shows the RQ values of a house sparrow fed on a high carbohydrate diet
(millet) and a high lipid diet (mealworms).
1.0
Key:
Millet
Mealworms
Respiratory quotient
0.9
0.8
0.7
0.6
0
1
5
3
2
4
Time after feeding / h
6
7
[Source: Walsberg and Wolf, Journal of Experimental Biology, (1995), 198, pages 213–219.
Reproduced by permission of The Company of Biologists Ltd]
(a)
Compare the RQ values for millet and mealworms between 1 hour and 6 hours after
feeding.
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(2)
The expected RQ value for house sparrows metabolizing millet is 0.93. The expected value
when metabolizing mealworms is 0.75.
4
(b)
Explain why the expected RQ values for millet and mealworms are different.
.....................................................................................................................................
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(2)
(c)
Suggest reasons for
(i)
the high initial RQ values for house sparrows fed on millet;
...........................................................................................................................
...........................................................................................................................
(1)
(ii)
the rapid fall in RQ values for house sparrows fed on millet.
...........................................................................................................................
...........................................................................................................................
(1)
(Total 6 marks)
5.
Explain the similarities and differences in anaerobic and aerobic cellular respiration.
(Total 8 marks)
5
6.
The mitochondrion carries out key reactions in the cells of eukaryotes.
A
B
[Source: D S Friend, Brigham and Women’s Hospital, www.nigms.nih.gov/ news/science_ed/mito1.html]
(a)
(i)
State the name of label A and label B in the photomicrograph above.
A:
...............................................................................................................
B:
...............................................................................................................
(1)
(ii)
State the processes that occur at label A and label B.
A:
...............................................................................................................
B:
...............................................................................................................
(1)
6
(b)
Explain the relationship between the structure of the mitochondrion and its function.
...................................................................................................................................
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(3)
(Total 5 marks)
7.
Explain the process of aerobic respiration including oxidative phosphorylation.
(Total 8 marks)
8.
(a)
Photosynthesis consists of two sets of reactions. State the names of these two sets.
......................................................................................................................................
......................................................................................................................................
(1)
(b)
Outline how one specific limiting factor affects the rate of photosynthesis.
......................................................................................................................................
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(2)
7
(c)
Explain the production of ATP by chemiosmosis during photosynthesis.
......................................................................................................................................
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......................................................................................................................................
(3)
(Total 6 marks)
9.
(a)
State two products of the process of glycolysis.
.....................................................................................................................................
.....................................................................................................................................
(1)
(b)
Explain the significance of polar and non-polar amino acids within the cell.
.....................................................................................................................................
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(3)
(Total 4 marks)
8
10.
(a)
State two functions of proteins with a named example of each.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(b)
Explain chemiosmosis as it occurs during cell respiration.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(Total 4 marks)
9
11.
The electron micrographs below show mitochondria in longitudinal section. The mitochondrion
in A is from a bat pancreas cell and that in B is from a mouse liver cell.
A.
B.
[Source: Tribe and Whittaker, Chloroplasts and Mitochondria, (1972), 31, pp 28–29]
(a)
Annotate the micrographs to show two similarities in the structure of the mitochondria.
(2)
(b)
The mitochondria differ in size. State two other differences that are visible in the
mitochondria.
1.
..........................................................................................................................
2.
..........................................................................................................................
(2)
10
(c)
Predict, with two reasons, which of the mitochondria would have been able to produce
ATP at a greater rate.
....................................................................................................................................
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....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
(3)
(Total 7 marks)
12.
(a)
(i)
Identify the cell organelle shown in the micrograph below.
...........................................................................................................................
(1)
11
(ii)
Identify the structure labelled I above and explain how it is adapted for the
organelle to function efficiently.
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(3)
(b)
Describe the role of acetyl CoA in the metabolism of lipids.
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(2)
(Total 6 marks)
13.
Anaerobic respiration occurs in the absence of oxygen while aerobic respiration requires
oxygen.
(a)
State one final product of anaerobic respiration.
.....................................................................................................................................
(1)
12
(b)
Complete the table showing the differences between oxidation and reduction.
Oxidation
Reduction
Electrons gained or
lost
Oxygen or hydrogen
gained or lost
(2)
(c)
The structure of a mitochondrion is shown in the electron micrograph below.
Name the parts labelled A, B and C and state the function of each.
Part A:
Name: ..........................................................................................................
Function: ......................................................................................................
Part B:
Name: ...........................................................................................................
Function: ......................................................................................................
Part C:
Name: ...........................................................................................................
Function: ......................................................................................................
(3)
(Total 6 marks)
13
14.
Studies have been carried out on the consumption of oxygen by mammals under different
conditions. The graph below shows the oxygen consumption of a pigmy possum (Cercaertus
nanus) at various air temperatures.
5
4
Oxygen
consumption
/ ml O 2 g - 1 h - 1
3
2
1
0
0
5
10
15
20
25
Air temperature / п‚°C
30
35
40
Knut Schmidt-Nielsen, Animal Physiology, Adaptation and Environment, 5ed (Cambridge:
Cambridge University Press, 1997). Reprinted with permission.
(a)
Estimate the oxygen consumption at 20п‚°C.
....................................................................................................................................
(1)
(b)
Outline the effect of temperature on oxygen consumption.
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....................................................................................................................................
....................................................................................................................................
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(2)
14
(c)
An air temperature of 32п‚°C is the lower critical temperature for a pigmy possum. Deduce
the meaning of lower critical temperature.
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
(1)
The graph below shows the metabolic rates of various mammals in relation to air temperatures.
Metabolic rate refers to the rate of use of energy by an animal and may be measured indirectly
by oxygen consumption. The basal metabolic rate (BMR) for each animal, in the absence of
stress, is given the value of 100пЂҐ. This occurs at different temperatures for different animals.
The changes in metabolic rate as the temperature falls are expressed as a percentage of the BMR
for each animal.
[Knut Schmidt-Nielsen, Animal Physiology, Adaptation and Environment, 5ed (Cambridge: Cambridge University Press, 1997).
Reprinted with permission.]
(d)
(i)
Identify the mammal with the greatest increase in metabolic rate per degree of
temperature, as the temperature decreases.
..........................................................................................................................
(1)
15
(ii)
Calculate the average change in the metabolic rate, per degree of temperature, of a
weasel as the temperature decreases from 17C to –20C. Show your workings.
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..........................................................................................................................
..........................................................................................................................
(2)
(e)
Suggest one reason for the increase in metabolic rate of mammals at lower temperatures.
....................................................................................................................................
....................................................................................................................................
(1)
(f)
Discuss the differences between tropical and arctic mammals regarding the changes in
their metabolic rates as the temperature decreases.
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(3)
16
Other studies were carried out to see the relationship of the thickness of fur in mammals to its
value as an insulator. A good insulator prevents heat loss from the animals to their environment.
The graph below shows the relationship of the fur thickness to fur insulation in different
mammals. Symbols represent the transfer of heat from fur to air or fur to ice water.
4.0
3.5
white fox
3.0
wolf
grizzly bear
polar bear
red fox
reindeer
2.5
rabbit
Fur insulation
value / W dm–2
dall sheep
dog
beaver
2.0
1.5
seal
lemming
squirrel
1.0
seal in ice water
weasel
0.5
shrew
beaver in ice water
polar bear in ice water
0.0
0
10
20
30
40
50
60
70
80
Fur thickness / mm
Key : ♦ = the rate of transfer of heat from fur to air
в—Љ = the rate of transfer of heat from fur to ice water
[Source: K Schmidt-Nielsen, Animal Physiology, Adaptation and Environment, (1978), CUP, pp 321]
(g)
(i)
Calculate the difference in fur thickness between a reindeer and a grizzly bear.
..........................................................................................................................
..........................................................................................................................
(1)
(ii)
Suggest a reason for their similar fur insulation value.
..........................................................................................................................
..........................................................................................................................
(1)
17
(h)
(i)
Calculate the change in the insulation value for a beaver when it enters ice water.
..........................................................................................................................
..........................................................................................................................
(1)
(ii)
Suggest an adaptation that allows a mammal to maintain its body temperature
while in ice water.
..........................................................................................................................
..........................................................................................................................
(1)
(i)
Discuss the relationship between metabolic rate and fur thickness in mammals.
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(3)
(Total 18 marks)
18
15.
The eastern oyster (Crassostrea virginica) is a marine mollusc that lives in estuaries. The
environmental surroundings of the eastern oyster, such as the temperature and concentration of
trace elements, are constantly changing. The trace element cadmium affects the mitochondria
and prevents them from carrying out their function efficiently. Investigators isolated
mitochondria from the oysters to study how the respiration rate changed while varying the water
temperature and the cadmium ion concentration.
3.0
Key:
2.5
Respiration
rate / arbitrary
units
15 В°C
25 В°C
35 В°C
1.5
1.0
0.5
0.0
0
1
5
10
15
Cadmium ion concentration / Вµ mol
20
dm–3
[Source: I M Sokolova, (2004), The Journal of Experimental Biology, 207, pages 2639–2648.
With permission of the Company of Biologists Ltd.]
(a)
State the relationship between the concentration of cadmium ions and respiration rate at
35п‚°C.
.....................................................................................................................................
.....................................................................................................................................
(1)
(b)
Compare the respiration rate of the mitochondria at cadmium ion concentrations of 0пЃ­mol
dm–3 and 50mol dm–3.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
19
(c)
Suggest one other environmental property of the water, apart from temperature and
mineral concentration, that may show daily changes.
.....................................................................................................................................
(1)
(d)
The investigators concluded that seasonal and global warming might make the eastern
oysters more likely to suffer from trace element poisoning.
Using the data, evaluate this hypothesis.
.....................................................................................................................................
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(3)
(Total 7 marks)
20
Mitochondrial electron transport defects (called mitochondrial myopathy) causes tiredness at
low levels of exercise and varies from mild to severe. Scientists measured oxygen delivery to
cells and oxygen use in cells of thirty-five patients with mitochondrial myopathy. The results
were compared to a control group of thirty-two healthy individuals. The results are shown in the
two charts below.
Oxygen delivery to cells
Oxygen use in cells
400
50
45
350
40
Rate/ml Kg–1min –1
Rate/ml Kg–1min –1
16.
300
250
200
35
30
25
20
15
10
150
5
Key:
mitochondrial myopathy group
control group
[Source: adapted from T. Taivassalo and R. G. Haller, (2006), �Exercise and training in mitochondrial myopathies’,
Medicine and Science in Sports and Exercise, 37 (12) 2094-2101, В© Lippincott Williams & Wilkins, USA]
(a)
State the mean value for oxygen delivery to cells in patients suffering from mitochondrial
myopathy.
......................................................................................................................................
(1)
(b)
Calculate the percentage difference of the oxygen use in cells by the control group
compared to oxygen use in cells of patients with mitochondrial myopathy.
................ %
(1)
21
(c)
Discuss why people with mitochondrial myopathy tire more easily than healthy
individuals.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
(Total 5 marks)
17.
The diagram below shows possible pathways for the breakdown of glucose in various cells.
Glucose
A
Process Q
(no oxygen present)
B
(a)
C+D
Process R
(oxygen present)
D+E
State the names of processes Q and R.
Q:
...........................................................................................................................
(1)
R:
...........................................................................................................................
(1)
(b)
Deduce the names of substances A and D.
A:
...........................................................................................................................
(1)
D:
...........................................................................................................................
(1)
22
(c)
State the organelle in which process R takes place.
.....................................................................................................................................
(1)
(Total 5 marks)
18.
Fruits remain alive for a period of time after harvesting. Cellular respiration continues and it can
greatly influence the maturation (ripening) process in the fruits. The rate of respiration depends
on many factors such as the type, quality, degree of ripeness and water content of the fruits,
temperature and air composition. Respiration that continues after harvesting may sometimes
lead to the over-ripening and eventual loss of an entire cargo of fruit during transport.
Studies of the maturation process in bananas are summarized in the following graph.
Relative rate
green
green/yellow
yellow
Time/arbitrary units (showing colour changes in bananas)
Key:
chlorophyll breakdown
starch breakdown
water release
CO 2 formation
Sugar formation
[Source: www.containerhandbuch.de/chb_e/scha/index.html?/chb_e/scha/scha_15_02_03_02.html]
(a)
(i)
State two chemical products released as gases during cellular respiration.
1 ........................................................................................................................
2 ........................................................................................................................
(1)
(ii)
State one non-chemical product of respiration.
...........................................................................................................................
(1)
(b)
Using the data, analyse the events that occur when maturation begins in bananas.
23
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.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(c)
Suggest, giving reasons, two ways in which transport conditions can be controlled to
minimize over-ripening.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(Total 6 marks)
24
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