1.
PanI is a gene in cod fish that codes for an integral membrane protein called pantophysin.
Two alleles of the gene, PanIA and PanIB, code for versions of pantophysin, that differ by four
amino acids in one region of the protein. Samples of cod fish were collected from 23 locations
in the north Atlantic and were tested to find the proportions of PanIA and PanIB alleles in each
population. The results are shown in pie charts, numbered 1–23, on the map below. The
proportions of alleles in a population are called the allele frequencies. The frequency of an allele
can vary from 0.0 to 1.0. The light grey sectors of the pie charts show the allele frequency of
PanIA and the black sectors show the allele frequency of PanIB.
[RAJ Case et al. 2005. “Macro- and micro-geographic variation in pantophysin (PanI) allele frequencies in NE
Atlantic cod Gadus morhua.” MEPS. Vol 301. Pp 267–278. Figs 1 and 3.]
(a)
(i)
State the two populations with the highest PanIB allele frequencies.
...........................................................................................................................
(1)
(ii)
State the population in which the allele frequencies were closest to 0.5.
...........................................................................................................................
(1)
IB Questionbank Biology
1
(b)
Deduce the allele frequencies of a population in which half of the cod fish had the
genotype PanIA PanIA, and half had the genotype PanIA PanIB.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(1)
The graphs below show the latitude and the mean surface sea temperature in June of the
sampling locations and the frequency of the PanIA allele.
[RAJ Case et al. 2005. “Macro- and micro-geographic variation in pantophysin (PanI) allele frequencies in NE
Atlantic cod Gadus morhua.” MEPS. Vol 301. Pp 267–278. Figs 1 and 3.]
(c)
State the relationship between
(i)
latitude and the frequency of the PanIA allele.
...........................................................................................................................
...........................................................................................................................
(1)
(ii)
mean surface sea temperature in June and the frequency of the PanIA allele.
...........................................................................................................................
...........................................................................................................................
(1)
(d)
Suggest how natural selection could have caused the relationships shown in the graphs.
......................................................................................................................................
IB Questionbank Biology
2
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(e)
The sites close to Iceland, at a latitude of 60–65°, had very varied allele frequencies, with
both PanIA and PanIB occurring. The water at these sample sites was highly stratified,
with much warmer water at the surface and much colder water below. Suggest reasons for
both PanIA and PanIB alleles occurring at these sites.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(f)
Using the data in this question, predict the effects of global warming on cod fish
populations.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 11 marks)
IB Questionbank Biology
3
2.
Tufted ducks (Aythya fuligula) are found in lakes and lagoons throughout Europe. They eat
molluscs, insects and plants, sometimes from the surface but mostly by diving under the water.
The graph shows how the heart rate of a tufted duck changes when diving under the water.
[R Stephenson, P J Butler and A J Woakes. 1986. “Diving behaviour and heart rate in tufted ducks (Aythya
fuligula).” J Exp Biol. Vol 126. Pp 341–359.]
(a)
State the length of time the tufted duck was under the water.
......................................................................................................................................
(1)
(b)
Outline the changes in the heart rate during the dive.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(c)
Suggest, with a reason, the type of respiration used by the tufted duck during the dive.
......................................................................................................................................
IB Questionbank Biology
4
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(1)
When swimming on the surface, the blood supply to different parts of the body of the tufted
duck varies according to whether it is swimming at normal speed or maximum speed.
[Source: Butler, PJ, Turner, DL, Al-Wassia, A & Bevan, RM. 1988. “Regional distribution of blood flow during
swimming in the tufted duck (Aythya fuligula).” J Exp Biol. Vol 135. Pp 461–472.]
IB Questionbank Biology
5
(d)
Calculate the percentage increase in blood flow to the leg muscles when the tufted duck
changes from swimming at normal speed to swimming at maximum speed.
......................................................................................................................................
(1)
(e)
Compare the blood flow to the heart muscles with the blood flow to the flight muscles
when changing from swimming at normal speed to swimming at maximum speed.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(f)
Explain the changes in blood flow that occur when swimming at maximum speed.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
IB Questionbank Biology
6
(g)
Predict, with reference to both graphs, what would happen to the blood flow to the heart
muscles when the tufted duck is diving.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(h)
State the hormone that affects heart rate.
......................................................................................................................................
......................................................................................................................................
(1)
(Total 12 marks)
IB Questionbank Biology
7
3.
Vitamin C is an important component of a healthy diet. Because it is water-soluble it cannot be
effectively stored and excess vitamin C is released in the urine. In order to investigate the ability
of the body to retain different chemical forms of vitamin C, 17 healthy, female university
students, between the ages of 18 and 22, were placed on a low vitamin C diet (< 5 mg per day)
for three days. The test subjects were divided into two groups and were given an oral vitamin C
loading of either ascorbic acid (176 mg) or dehydroascorbic acid (174 mg). Levels of vitamin C
in the urine were measured six hours before and at regular intervals over a 24 hour period
following vitamin C loading. The negative value indicates time before vitamin C loading.
[Masaru Tsujimura, Shizu Higasa, Kazuhiro Nakayama, Yoshiko Yanagisawa, Sadahiko Iwamoto and Yasuo
Kagawa. 2008. “Vitamin C activity of dehydroascorbic acid in humans — Association between changes in the blood
vitamin c concentration or urinary excretion after oral loading.” J Nutr Sci Vitaminol. Vol 54. Pp 315–320, 1 table.]
(a)
State the urinary vitamin C content for each of the two study groups six hours before
vitamin C loading.
Ascorbic acid: ..............................................................................................................
Dehyrdoascorbic acid: .................................................................................................
(1)
IB Questionbank Biology
8
(b)
Calculate the percentage increase in urine levels of vitamin C for the ascorbic acid study
group during the first three hours after vitamin C loading.
........................................... %
(1)
(c)
Compare the trends in vitamin C release for the two test groups during the first twelve
hours after vitamin C loading.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(d)
Large individual differences in the urine level of ascorbic acid and dehydroascorbic acid
were recorded between test subjects after 24 hours. Suggest one possible reason for these
large individual differences.
......................................................................................................................................
......................................................................................................................................
(1)
IB Questionbank Biology
9
(e)
Scurvy is a disease that is due to vitamin C deficiency. Evaluate the importance of this
investigation for finding ways to combat vitamin C deficiency.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 7 marks)
4.
Physiological data were collected for a sample of 12 obese subjects across a range of exercise
machines. The average age of the subjects was 47 years and the average mass was 101.6 kg. The
subjects completed 15-minute trials on each machine at a self-selected, moderate intensity.
Mean values and, in some cases, standard deviations, are shown for the collected data.
Weight-bearing machines
Variable
Non weight-bearing machines
Treadmill
Body Trec
Stationary
Cycle
Airdyne
VO2 / cm3 kg–1 min–1
13.5
16.4
10.8
12.5
Heart rate / bpm
110
128
109
118
O2supply / cm3 beat–1
12.3
12.9
10.1
10.9
Ventilation rate / dm3 min–1
30.8 ± 8
39.7 ± 10
29.7 ± 14
31.2 ± 9
Energy expenditure / kJ min–1
27.5 ± 8.8
33.4 ± 8.4
22.2 ± 8.6
26.3 ± 8.4
Blood lactate / mM
2.82 ± 1.33
3.97 ± 1.77
3.35 ± 1.19
3.67 ± 1.63
[Jong-Kyung Kim, Hosung Nho and Mitchell H Whaley. 2008. “Inter-modal comparisons of acute energy expenditure
during perceptually based exercise in obese adults.” J Nutr Sci Vitaminol. Vol 54. Pp 39–45.]
(a)
Calculate the average O2 supply in cm3 beat–1 for the weight-bearing machines.
......................................................................................................................................
......................................................................................................................................
(1)
IB Questionbank Biology
10
(b)
Suggest one reason for the higher VO2 recorded for weight-bearing machines, compared
to non weight-bearing machines.
......................................................................................................................................
......................................................................................................................................
(1)
(c)
Analyse the energy expenditure for the four exercise machines.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(d)
Based on these data, discuss the advantages and disadvantages of the body trec for obese
subjects undergoing moderate exercise.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
(Total 7 marks)
IB Questionbank Biology
11
5.
The rate of photosynthesis in the marine seagrass, Zostera marina, was investigated under a
range of pH conditions. After a period of darkness, the plants were illuminated at a constant
light intensity at 15°C and the rate of photosynthesis was measured. Zostera marina can use
both dissolved carbon dioxide (CO2) and hydrogen carbonate ions for photosynthesis. The rate
of photosynthesis is plotted on the y-axis on the left. In addition, the concentration of carbon
dioxide was measured for each pH investigated and is plotted on the y-axis on the right.
[Source: Plant physiology by AMERICAN SOCIETY OF PLANT PHYSIOLOGISTS. Copyright 2008 Reproduced
with permission of AMERICAN SOCIETY OF PLANT BIOLOGISTS in the format CD ROM via Copyright
Clearance Center.]
(a)
State the carbon dioxide concentration at pH 7.2.
......................................................................................................................................
......................................................................................................................................
(1)
IB Questionbank Biology
12
(b)
Calculate the percentage decrease in the rate of photosynthesis from pH 7 to pH 7.5.
......................................................................................................................................
......................................................................................................................................
(1)
(c)
Outline the relationship between pH and the rate of photosynthesis.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(d)
Suggest how Zostera marina can perform photosynthesis even at very low carbon dioxide
concentrations.
......................................................................................................................................
......................................................................................................................................
(1)
(e)
Based on the information and data provided, discuss the role of one limiting factor, other
than carbon dioxide, and suggest how this would affect the rate of photosynthesis.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 7 marks)
IB Questionbank Biology
13
6.
The graph below shows the monthly mean values of terrestrial invertebrates from May 1997 to
June 1998 in the northern hemisphere. The light line shows the biomass of invertebrates which
are prey to forest birds (terrestrial invertebrate biomass). The darker line shows the invertebrates
which lived in the stream and have moved to the forest (aquatic invertebrate flux or movement).
The black bars on the horizontal line at the bottom show periods when trees have leaves and the
white bars show periods of defoliation.
[S Nakano and M Murakami. 2001. “Reciprocal subsidies: Dynamic interdependence between terrestrial and aquatic
food webs.” PNAS. Vol 98, issue 1. Pp 166–170. Figure 1C. Copyright (2001) National Academy of Sciences, USA.]
(a)
State the mean terrestrial invertebrate biomass measured in August.
......................................................................................................................................
(1)
(b)
Describe the trend in the aquatic invertebrate flux.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(c)
Suggest the relationship between defoliation and the amount of terrestrial invertebrates in
the forest.
IB Questionbank Biology
14
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(d)
Suggest a possible explanation for the pattern in aquatic invertebrate flux to the forest
seen between the months of June and December.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 7 marks)
IB Questionbank Biology
15
7.
In Australia, a study was undertaken among women to determine the vitamin D levels in their
blood. Levels of vitamin D were categorized as sufficient, insufficient and deficient to
determine how prevalent each category was. Three locations at three different latitudes and four
different seasons were used. A data summary is shown in the graphs below.
[Source: Van der Mei, IA, Ponsonby, A-L, Engelsen, O, Pasco, JA, McGrath, JJ et al. 2007. “The high prevalence of
vitamin D insufficiency across Australian populations is only partly explained by season and latitude.” Environ
Health Perspect. Vol 115, issue 8. DOI:10.1289/ehp.9937.]
IB Questionbank Biology
16
(a)
(i)
Identify the season when the women are least likely to suffer from vitamin D
deficiency.
...........................................................................................................................
(1)
(ii)
Using the data from all four seasons, identify the two locations where the patterns
of vitamin D are most similar.
...........................................................................................................................
...........................................................................................................................
(1)
(iii)
Determine what percentage of women in Geelong have insufficient vitamin D
levels in winter.
...........................................................................................................................
(1)
(b)
Compare the deficiency levels of vitamin D at all three locations.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
IB Questionbank Biology
17
(c)
Location and season were found to account for only a small part of the deficiencies.
Suggest, with reasons, how the behaviours of different people could influence the levels
of vitamin D in their blood.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 8 marks)
IB Questionbank Biology
18
Suggested solutions:
8.
(a) (i) (population) 1 and (population) 2 (both needed)
1
(ii)
1
(population) 11/7/7 and 11
(b)
PanIA 0.75 and PanIB 0.25 / 3 PanIA to 1 PanIB
Both must be correct for the mark to be awarded, accept
frequencies in form of ratio.
(c)
(i)
(ii)
(d)
(e)
(f)
1
greatest/great frequencies of PanIA at lowest/low latitudes /
a rapid drop in frequency at (60–65 degrees latitude) /
lowest/low frequencies at highest/high latitudes
Answers which describe/imply the correct step-wise relationship
should get credit. Answers stating or implying a negative
correlation alone should not get credit.
1
lowest/low frequencies of PanIA at lowest/low temperatures /
a rapid increase in frequency at (8–10 degrees Celsius) /
highest/high frequencies at warmest/warm temperatures
Answers which describe/imply the correct step-wise relationship
should get credit. Answers stating or implying a negative
correlation alone should not get credit.
1
(cod with) PanIA allele selected/favoured/better adapted to warmer water;
(cod with) PanIB allele selected/favoured/better adapted to colder water;
cod that survive can reproduce and pass alleles on to offspring;
It takes a whole organism to reproduce in order to pass on the allele,
hence we expect reference to the fish to gain this last marking point.
2 max
higher frequency of PanIA/PanIA PanIA (cod) in warm (surface) water;
higher frequency of PanIB/PanIB PanIB (cod) in colder (deeper) water;
interbreeding results in PanIA PanIB cod/heterozygous cod;
2 max
PanIA PanIA (cod) may spread further north / PanIB PanIB (cod)
may move/retreat further north;
numbers of PanIA PanIA (cod) may increase / frequency of PanIA
allele may increase;
PanIB PanIB (cod) may become extinct / frequency of PanIB allele
may decrease;
2 max
[11]
IB Questionbank Biology
19
9.
(a)
40 s/seconds (units required)
(b)
initially the heart rate decreases rapidly;
heart rate increases over the next seconds;
heart rate falls to its lowest level / reaches lowest level after
55 s/seconds / 35 s/seconds after start of dive;
in the last seconds before the dive ends, the heart rate increases;
(c)
(d)
1
anaerobic respiration because the tufted duck cannot breathe/
ventilate under water / replace oxygen that has been used;
aerobic respiration because the tufted duck uses stored oxygen;
both aerobic (at the beginning) and anaerobic (at the end) because
oxygen was used up during the dive;
To award [1], reason must be given.
2 max
1 max
200 (%)
1
(e)
Heart muscles
(f)
(g)
(h)
Flight muscles
swimming at maximum speed
causes increase in blood flow to
heart muscles
swimming at maximum speed causes
decrease in blood flow to flight
muscles;
swimming at normal speed, less
blood flow to heart muscles (20 ml
min–1) / swimming at maximum
speed, more blood flow to heart
muscles (24 ml min–1)
swimming at normal speed, greater
blood flow to flight muscles (39 ml
min–1) / swimming at maximum
speed, less blood flow to flight
muscles (18 ml min–1);
small change in blood flow to heart
muscles when changing speed (4 ml
min–1 more)
big change/almost half amount of
blood flow to flight muscles when
changing speed (22 ml min–1 less);
Award [1] for each correct row. Answers do not need to be shown
in a table format, but must be comparative statements.
2 max
legs/leg muscles need more energy/ATP for fast swimming;
legs/leg muscles need more blood to provide oxygen/glucose for energy;
(the legs need more blood) to remove carbon dioxide;
the heart needs more blood to pump faster;
intestines/kidneys/flight muscles have less blood to allow for
increased flow to heart/legs;
2 max
blood flow decreases;
as heart rate is seen to decrease in the first graph;
as lower heart rate means less requirement for oxygen/nutrients/
blood/removal of waste;
2 max
adrenaline / epinephrine / noradrenaline / norepinephrine
1
[12]
IB Questionbank Biology
20
10. (a) Ascorbic acid: 2 mg (units are needed)
Dehydroascorbic acid: 2 mg (units are needed)
Both required for the mark.
(b)
(c)
(d)
(e)
400 (%) (working not required)
more ascorbic acid (40 mg) than dehydroascorbic acid (33 mg)
is released/excreted;
more dehydroascorbic acid (16 mg) than ascorbic acid (10 mg)
is released/excreted in the first three hours / dehydroascorbic
acid peaks before ascorbic acid;
from six hours onwards more ascorbic acid is released than
dehydroascorbic acid;
maximum release of dehydroascorbic acid at three hours
whereas maximum release of ascorbic acid at six hours;
ascorbic acid release rises then falls whereas dehydroascorbic
release falls (until 12 hours after loading);
genetic variability / differences in vitamin C metabolism /
differences in vitamin C requirements / differences in levels
of uptake into blood / size/weight of individuals
both chemical forms are released/excreted so supplements
need to be given regularly;
using dehydroascorbic acid instead of ascorbic acid does
not improve vitamin C retention / dehydroascorbic acid could
be marginally better as less is excreted;
study only looks at young/healthy/female subjects;
period of vitamin C deficiency is too short / need a longer
period to allow scurvy to develop;
1
1
2 max
1
2 max
[7]
11.
(a)
12.6 cm3 beat–1 (units required)
(b)
muscles working harder / require more O2 / moving the whole body;
intensity of exercise (on weight-bearing machines) is higher;
muscles supporting body weight are also active;
1 max
weight-bearing machines require higher energy expenditure
(than non weight-bearing);
body trec highest energy expenditure and stationary cycle lowest;
large standard deviations for all machines / large range of values
amongst participants / no clear trend apparent;
2 max
(c)
1
(d) Advantages: [2 max]
energy expenditure is higher so greater weight loss/greater use of
carbohydrates/fats;
shorter recovery times needed due to higher oxygen supply;
heart rate is increased but not to an excessive level;
higher ventilation rate means more aerobic respiration (although
lactate levels indicate more anaerobic respiration as well);
Disadvantages:
possible strain on joints;
body trec results in very high blood lactate values;
increased heart rate potentially dangerous for obese subjects / too
much stress for obese subjects (as indicated by high lactate levels);
3 max
[7]
IB Questionbank Biology
21
12.
(a)
200 μM (units required)
1
(b)
(77–51)/77×100 = 35% (Units required. Allow answers
in the range of 32–37%.)
1
(c)
(d)
(e)
highest rate of photosynthesis at pH 7;
decrease (in rate of photosynthesis) between pH 7 and pH 7.5;
little change (in rate of photosynthesis) at higher pH values;
rate of photosynthesis falls again (slightly) at pH 9;
2 max
uses hydrogen carbonate ions;
uses stored carbon dioxide / carbon dioxide from respiration;
1 max
pH
optimum pH may be less than 7;
reducing the pH below 7 may lead to a higher rate (of photosynthesis);
(but) enzyme activity can be affected by low pH;
or
Temperature
optimum temperature may not be 15ºC;
enzyme activity is affected by temperature;
temperatures above (or below) 15ºC may lead to a higher rate
(of photosynthesis);
or
Light intensity
light intensity may not be optimal/may be limiting;
too low light intensity produces less ATP/NADPH + H+;
higher light intensities may result in a higher rate (of photosynthesis);
as light intensity/temperature increases rate of photosynthesis
may not increase as another factor becomes limiting;
[1] for named limiting factor and [1] for effect on photosynthesis.
2 max
[7]
13.
(a)
166 mg m–2 (Allow answers in the range of 162–168 mg m–2)
(b)
rapid rise and fall between April and August;
peak in May/June;
fluctuates between August/September and December;
low December/January until February/March;
cyclical;
2 max
negative relationship / during period of defoliation, biomass
(of terrestrial invertebrates) is at its lowest;
less leaves means less food/habitats / easier for predators to
see invertebrates;
defoliation occurs in winter/autumn and the cold may kill
invertebrates;
2 max
(c)
IB Questionbank Biology
1
22
(d)
(aquatic invertebrate flux) decreases because movement to the
forest has occurred (by adult forms) / fewer aquatic invertebrates
left in the stream so fewer are moving;
fluctuation due to movement of different species/different life
cycles/second generation;
decreases because invertebrates left at the beginning of
winter/cold season;
(adult forms) move to utilize (changes in) food supply in forest;
2 max
[7]
14.
(a)
(b)
(i)
summer
1
(ii)
Geelong and (Southeast) Queensland (both needed)
1
(iii)
(40 – 8) = 32% (accept answers in the range of 31% to 33%)
1
similarity:
none of the locations are deficient in Summer;
Geelong and (Southeast) Queensland have similar prevalence/levels
of deficiency at all times of the year;
difference:
only Tasmania shows a deficiency in autumn;
Tasmania shows the highest prevalence of deficiency;
(Southeast) Queensland shows less prevalence/levels of deficiency overall;
To award [3], answers must address at least one similarity and
one difference.
(c)
diets rich in vitamin D could raise vitamin D levels; (vice versa)
use of sunscreen/staying out of the sun/hats/clothing can reduce
the production of vitamin D by the skin; (vice versa)
use of dietary supplements containing vitamin D can reduce
deficiency levels;
3 max
2 max
[8]
IB Questionbank Biology
23