T6-1
[244 marks]
1a. Describe the process of blood clotting.
[4 marks]
[6 marks]
1b. Factor IX is a blood clotting protein which some hemophiliacs lack. In the future hemophilia could be treated
using clotting factors synthesized by genetically modified bacteria. Outline the basic technique used for this gene transfer.
1c.
Explain how males inherit hemophilia and how females can become carriers for the condition.
[8 marks]
2a. Draw a labelled diagram of a mitochondrion as seen in an electron micrograph.
[4 marks]
2b. A supply of oxygen is needed for aerobic respiration in mitochondria. Describe the features of alveoli in human
lungs that adapt them for efficient absorption of oxygen.
[6 marks]
2c.
Explain the mechanism of ventilation of human lungs.
3a. Outline how and where energy is stored in plants.
[8 marks]
[4 marks]
3b.
3c.
Ecologists sometimes display data from an ecosystem using a diagram called a pyramid of energy. Describe
what is shown in pyramids of energy.
[6 marks]
Explain the control of body temperature in humans.
[8 marks]
4a. Describe four different types of transport of substances across a membrane.
[4 marks]
4b.
Hormones such as FSH (follicle stimulating hormone) and LH (luteinizing hormone) affect the development of
[6 marks]
certain cells by binding to receptors in the plasma membranes. Outline the role of FSH and LH in the menstrual cycle.
4c. In the placenta, many substances are transported across membranes. Explain the structure and role of the
placenta.
5.
Immediately after an action potential, which event causes the neuron membrane to repolarize?
A. Voltage-gated sodium channels open.
B. Voltage-gated potassium channels open.
C. Voltage-gated calcium channels close.
D. Voltage-gated potassium channels close.
[8 marks]
[1 mark]
6.
What is a characteristic of type II diabetes?
[1 mark]
A. Liver cells are less sensitive to insulin.
B. Insulin is no longer produced.
C. α cells in the pancreatic islets are destroyed.
D. β cells in the pancreatic islets are destroyed.
7.
What is the function of LH (luteinizing hormone) in the menstrual cycle?
A. Development of follicles in the ovary
B. Repair of the uterus lining following menstruation
C. Stimulation of ovulation
D. Preparation of the uterus for implantation
[1 mark]
8.
9.
Enzymes produced by the pancreas could pass out of the body via the anus. Which route would these enzymes
take to do this?
[1 mark]
What causes the rate of heart contraction to increase or decrease?
[1 mark]
A. The heart muscle itself
B. Nerve impulses from the brain
C. A hormone from the thyroid gland
D. The rate of return of blood to the left atrium
10.
Why do nutrient molecules enter the blood?
A. Blood carries nutrients to cells.
B. Blood converts nutrients into energy.
C. Nutrients and oxygen are mixed by blood.
D. Nutrients are stored in blood.
[1 mark]
11.
12.
Where are structures I, II and III found in the human body?
[1 mark]
What initiates an action potential along a neuron?
[1 mark]
A. Potassium and sodium ions diffuse out of a neuron.
B. Potassium and sodium ions diffuse into a neuron.
C. Neurotransmitters cause depolarization of membrane.
D. Acetylcholinesterase breaks down acetylcholine.
13.
Why does shivering occur?
[1 mark]
A. The body cannot control muscles when they become cold.
B. Shivering informs the brain that the body is too cold.
C. Shivering generates heat and raises body temperature.
D. The body diverts blood away from skin reducing heat loss.
14.
What is the function of thrombin in the process of blood clotting?
A. It acts as a catalyst.
B. It criss-crosses the wound to trap blood cells.
C. It changes from a soluble protein to an insoluble fibrous protein.
D. It releases clotting factors from platelets.
[1 mark]
Exposure to organophosphorus pesticides (OP) is a cause of serious nerve damage. It disrupts synaptic transmission by
inhibiting the enzyme acetylcholinesterase, causing death due to cardiovascular and respiratory failure.
Recombinant human acetylcholinesterase (rAChE) was obtained by genetic engineering and produced in Nicotiana
benthamiana plants. It was tested as a new therapeutic treatment in mice that were exposed to OP. The following
graph shows the severity of the symptoms shown by each mouse at different ratios of rAChE to OP.
15a.
15b.
State the minimum ratio at which some mice showed no symptoms.
Analyse the effect of increasing the ratio of rAChE to OP on the symptoms in mice.
[1 mark]
[3 marks]
15c.
Predict what would happen if a mouse received 300 mg of rAChE and 600 mg of OP.
[2 marks]
To test the effect of OP damage on synapses, mice were treated with rAChE, OP or both. Their diaphragms were
dissected 10 days after treatment. The area of the synapse between axons and the diaphragm was measured. When
the synapses are damaged by OP there is a greater area. The box plot shows the effect of different treatments on the
area of the synapse.
15d.
Calculate the difference in median area of synapse between the control mice and mice treated with rAChE and
OP, giving the units.
[1 mark]
15e.
15f.
16a.
Describe the evidence for damage to synapses by OP provided by data in the box plot.
[2 marks]
Using the data from both graphs, evaluate the hypothesis that plant-produced rAChE could be used to protect
humans or other mammals from damage caused by exposure to OP.
[2 marks]
Describe the properties of water that make it a useful component of blood.
[4 marks]
16b.
16c.
17a.
17b.
Explain the relationship between structure and function of arteries, capillaries and veins.
[8 marks]
Outline how leucocytes defend the body against pathogens.
[6 marks]
State the source, substrate, products and optimal pH condition for lipase in the human digestive system.
[4 marks]
Outline the use of named enzymes in gene transfer using plasmids.
[6 marks]
17c.
18a.
18b.
Explain the effect of changes of pH, substrate concentration and temperature on enzyme activity.
[8 marks]
State the functions of the following organelles of a eukaryotic animal cell: lysosome, Golgi apparatus, free
ribosomes, plasma membrane, rough endoplasmic reticulum.
[5 marks]
Distinguish between anaerobic and aerobic cell respiration in eukaryotes.
[4 marks]
18c.
19a.
19b.
Explain the mechanism of ventilation in the lungs in order to promote gas exchange for cell respiration.
[9 marks]
Ecologists sometimes display data from an ecosystem using a diagram called a pyramid of energy. Describe
what is shown in pyramids of energy.
[6 marks]
Explain the control of body temperature in humans.
[8 marks]
Scientists investigated if training has an influence on the learning of birdsong. They studied juvenile zebra finches
(Taeniopygia guttata) that had never been exposed to adult bird songs. They measured neuron activity in an area of
the brain involved with song learning. This was done during their sleep, first for four nights when the birds had not
heard any birdsong during the previous day, and then for a series of nights after days when they were exposed to
recordings of adult zebra finches’ songs. In the graph below, the mean neuron activity in the period of no exposure to
birdsong was used as a baseline and assigned a value of 1. All other measurements of neuron activity are shown
relative to this.
20a.
State the difference in neuron activity between nights 2 and 7.
20b. Outline the effect of exposure to birdsong on neuron activity.
[1 mark]
[2 marks]
20c.
20d.
Suggest one reason for the large error bars on days 14 and 15.
Evaluate the hypothesis that listening to other zebra finches is important to develop singing ability amongst
juveniles.
[1 mark]
[2 marks]
The yeast Brettanomyces bruxellensis is a contaminant of wine which when present produces acetic acid, the main
component of vinegar. The presence of acetic acid can lead to economic losses as it alters the taste of the wine and
inhibits the growth of Saccharomyces cerevisiae, thus decreasing the ethanol production. Scientists investigated the
effect of changing the temperature in fermentation tanks containing only Brettanomyces bruxellensis and a growth
medium containing glucose in order to understand the dynamics of this contaminant.
20e.
State the concentration of glucose at 20°C after 110 hours of incubation, giving the units.
[1 mark]
The nitrogen content of a leaf is mainly due to the proteins contained in the chloroplasts. These proteins are either in
the thylakoids or in the stroma, where most enzymes are found. The quantity of nitrogen from the thylakoids is directly
proportional to the amount of chlorophyll; a ratio of approximately 50 mmol nitrogen : 1 mmol chlorophyll
would represent 100 % of the leaf nitrogen content. Scientists hypothesized that the higher leaf percentage nitrogen
content resulting from a decrease in light intensity is due mainly to an increase in chlorophyll in many plant species,
three of which are represented in the following graph.
20f.
State the difference in chlorophyll content for Phaseolus between high and low light intensity, giving the units.
[1 mark]
Scientists investigated astronauts’ cardiovascular response to exercise in weightless conditions during a Columbia
Space Shuttle mission. They measured the blood pressure and the time between heartbeats, both at rest and during
moderate exercise. Blood pressure is expressed by two values corresponding to ventricular contraction (systole) and
relaxation (diastole). Measurements were taken before the flight, early in the flight and during the second week in
space. The following graphs represent average values for each type of measurement.
20g.
Calculate the difference in blood pressure at systole between rest and exercise before flight, giving the units.
[1 mark]
Elderly people lose bone mineral density (BMD) with age, and this is the source of many health issues, including higher
risk of bone fractures. Researchers measured the change in BMD amongst elderly men considering many factors, over
a period of four years. The results presented below show the difference between bone density change due solely to
vitamin C intake and bone density loss considering a combination of the other factors represented by the baseline
(zero). BMD was measured in the spine and at two femur (thigh bone) locations (femoral neck and trochanter) using
scanner images. Daily intake of total vitamin C was categorized as high, medium or low.
20h.
Outline the effect of vitamin C intake on changes in bone density in the spine.
[1 mark]
Scientists studied the characteristics of plant species growing in front of the progressively receding Rutor glacier in
Italy. As the ice recedes plants are able to colonize the exposed ground. In a study of primary succession, scientists
sampled plants from three areas exposed during different time periods. The data is shown in the following triangle
graph.
Each species is represented by a number and positioned according to its degree of competitiveness (the ability to
exclude other species), stress-tolerance (the ability to use nutrients efficiently) and ruderalism (the ability to develop
rapidly to avoid disturbance).
Stages of succession were classified according to the time the ground had been exposed: early succession (species
occurring in ground exposed for less than 68 years), mid-succession (species found in ground exposed between 69
and 181 years) and late-succession (species found in ground exposed for more than 181 years).
20i.
State the most ruderal species.
[1 mark]
Species number 4 has a ruderalism value of 29. State the stress-tolerance value and competitiveness value of
this species.
20j.
[1 mark]
Stress-tolerance value: ......................
Competitiveness value: ......................
20k.
20l.
Analyse the change of species over time.
State the effect of increasing temperature from 20°C to 30 °C on the rate of production of ethanol.
[3 marks]
[1 mark]
20m.
State the percentage value of total leaf nitrogen in chlorophyll for Spinacia at low light intensity.
[1 mark]
......................%
20n.
20o.
Outline the response of the astronauts’ cardiovascular system to exercise before the flight.
[2 marks]
Compare the changes in bone density of the femoral neck with those of the spine.
[2 marks]
20p.
20q.
20r.
Suggest one advantage for plants to increase their leaf chlorophyll content per surface area when light intensity [1 mark]
is lower.
Discuss whether the cardiovascular system has to adjust to weightless conditions in space.
[3 marks]
Evaluate the evidence provided by the data that the intake of vitamin C supplements may reduce bone density [2 marks]
loss in elderly people.
20s.
Deduce one reason why there were no more rises in ethanol concentration after 120 hours at 30°.
[1 mark]
20t.
Deduce one reason why the concentration of ethanol and acetic acid at 35°C does not rise after 80 hours despite [1 mark]
the fact that the concentration of glucose is still high.
20u.
Discuss the idea of producing wine using a lower temperature range to avoid economic losses due to
contamination by yeasts other than S. cerevisiae.
[3 marks]
20v.
21a.
Evaluate the hypothesis that lower light intensity increases thylakoid nitrogen.
[3 marks]
Label the following diagram of the eye.
[2 marks]
21b.
Outline the diversity of stimuli that can be detected by human chemoreceptors.
[2 marks]
The following image represents a model of ribulose bisphosphate (RuBP) carboxylase (also known as Rubisco) from
the green alga Chlamydomonas.
21c. Identify the level of protein structure of the part labelled X.
[1 mark]
21d. State the role of ribulose bisphosphate (RuBP) carboxylase in the Calvin cycle.
[1 mark]
21e. State the role of ligaments in human movement.
[1 mark]
The following are from the labels of a bag of all purpose white flour (wheat) and a bag of parboil long grain rice.
Amounts shown are per serving.
21f.
21g.
Compare wheat flour and rice as main dietary sources of energy for humans.
[2 marks]
Explain non-competitive inhibition.
[2 marks]
21h.
21i.
Evaluate the benefits of reducing dietary cholesterol in lowering the risk of coronary heart disease.
Explain the changes in ventilation rate during exercise.
[2 marks]
[2 marks]
22a.
The diagram below shows a synapse where the neurotransmitter is dopamine and some of the processes that
take place during nerve transmission.
[3 marks]
Explain the effect of cocaine on neurotransmission at a synapse.
22b. Compare convergent and divergent evolution.
[2 marks]
22c. Explain how polyploidy can contribute to speciation.
[4 marks]
22d. Explain the relationship between the action spectrum and the absorption spectrum of photosynthetic pigments [3 marks]
in plants.
22e. Discuss the difficulties of classifying organisms into trophic levels.
[2 marks]
22f. Draw a labelled diagram to show the structure of a sarcomere.
[2 marks]
22g. Outline the control mechanism for appetite in humans.
[2 marks]
22h. Explain the cause and consequences of biomagnification, using a named example.
[4 marks]
22i. Explain the consequences of releasing raw sewage and nitrate fertilizer into rivers.
[4 marks]
22j. Explain the roles of actin and myosin in muscle contraction.
[4 marks]
22k.
Explain the possible health consequences of a diet rich in protein.
© International Baccalaureate Organization 2017
International Baccalaureate® - Baccalauréat International® - Bachillerato Internacional®
[3 marks]