Question 1
1
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. \footnotetext{ R. Stephenson, P. J. Butler and A. J. Woakes, "Diving behaviour and heart rate in tufted ducks (Aythya fuligula)", J Exp Biol (1986) 126:341359. Reproduced with permission. }
12 marks
Question 1(c)
1(c)
Suggest, with a reason, the type of respiration used by the tufted duck during the dive. 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. Butler, P.J., Turner, D.L., Al-Wassia, A. \& Bevan, R.M. 1988. Regional distribution of blood flow during swimming in the tufted duck (Aythya fuligula). J. exp. Biol. 135, 461-472. Reproduced with permission.
Mediumstructured1 marks
Answer
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.
Question 1
1
Ozone gas in the atmosphere helps to block high-energy ultraviolet light (UV) from reaching the Earth's surface. Over the past few decades, the ozone layer has been decreasing, thus allowing through more UV. The effect of this decrease in the ozone has been studied in different plants. An early study was undertaken on patience dock plants (Rumex patientia) to test the effect of atmospheric ozone levels decreasing by 38 %. The net photosynthesis (total photosynthesis minus total respiration) and respiration of the plants were measured during seven days of exposure to UV. The rates of photosynthesis and respiration are given in rates of carbon dioxide uptake per unit area of leaf.
10 marks
Question 1(b)
1(b)
Distinguish between the results for the plants exposed to UV and the controls without UV in
0 marks
Question 1(b)(ii)
1(b)(ii)
respiration.
Easystructured2 marks
Answer
the rate of respiration of control is less than plants exposed to UV; respiration rate increased in the UV exposed plants early/days 1 to 2 / little change occured as the experiment progressed/days 4 and 7 while control plants remain more stable/slightly decrease; there are more fluctuations/variability/increases and decreases in the respiration rate of the UV exposed plants than in control plants;
Question 1
1
Researchers investigating human evolution recorded energy use for the brain, gastrointestinal tract (gut), liver, kidneys and heart as a percentage of total energy used in the human body. They found that these organs use around 70 % of the body's energy although they account for only about 7 % of body mass. They also compared the mass of each of these organs in humans with other modern primates, each with a body mass of 65 kg as shown in the bar chart.
0 marks
Question 1(c)
1(c)
Using information from the table and the graph, identify the human organ which uses the greatest amount of energy per kilogram of body tissue.
Mediumdata_response1 marks
Answer
heart
Question 1
1
Sockeye salmon (Oncorhynchus nerka) spend the first years of their lives in the freshwater lakes of Alaska before migrating to marine waters. Their first months in marine waters are spent foraging and growing near the shore line. They then move to offshore regions of the North Pacific Ocean for 2 to 3 years. The graph shows fork length frequency of juvenile O. nerka caught during their first months in marine waters in autumn 2008 and ocean age one O. nerka caught 15 months later during winter 2009 in the North Pacific Ocean.
14 marks
Question 1(d)
1(d)
Lipid in O. nerka was measured to evaluate possible differences in energy status during their first 15 months at sea. The graph shows the relationship between fork length and lipid content for O. nerka caught during autumn 2008 and winter 2009. State the range of lipid content measured in O. nerka caught during autumn 2008.
Easydata_response1 marks
Answer
11.7 g ; (accept answers in the range of 11.4 to 13.0 g ) 1.8 to 13.5 g ; (accept answers in the range of 1.6 to 2.0 g and 13.4 to 13.6 g )
Question 1(f)
1(f)
Suggest reasons for the differences in lipid content.
Mediumdata_response2 marks
Answer
lipid stores accumulated during summer/in freshwater/before moving out to sea; food resources/availability may decline rapidly during autumn/winter; more food close to the shore (than in offshore water); lipid stores used up during winter / more active/migrating in winter; Do not accept answers relating to the size of O. nerka because O. nerka with similar sizes showed different lipid content values.
Question 1
1
In an experiment measuring oxygen consumption, a laboratory mouse was placed in a respirometer for a short time. Soda lime solution absorbed any carbon dioxide produced during the experiment.
0 marks
Question 1(a)
1(a)
Suggest the purpose of the wire mesh.
Mediumstructured1 marks
Answer
a. allow gases to pass between mouse and soda lime b. prevent mouse getting in contact with soda lime c. prevent mouse from being in contact with faeces/urine/droppings 1 max
Question 1(b)
1(b)
Describe how the apparatus measures the oxygen consumption of the mouse.
Mediumstructured3 marks
Answer
a. more oxygen in inhaled air than in exhaled air OR mouse uses oxygen in respiration b. carbon dioxide exhaled / produced by mouse is absorbed by the soda lime c. difference in volume is oxygen used by mouse OR the volume/concentration/pressure of oxygen in the jar falls d. «this» sucks the coloured liquid up the tube e. volume of oxygen consumed equals the increase in volume of coloured water in the tube Source/mouse must be mentioned for marking point b - not just "sodalime absorbs \(\mathrm{CO}_{2}\) ". 3 max
Question 1(c)
1(c)
Discuss whether the apparatus would be suitable for measuring the oxygen consumption of a small green plant during respiration.
Mediumstructured3 marks
Answer
a. oxygen released during photosynthesis b. plants use carbon dioxide (released by respiration) c. if carbon dioxide is too low in concentration then photosynthesis will be eliminated/reduced d. results in an inaccurate/low measure of the oxygen that is consumed e. perform experiment in dark to prevent photosynthesis OR cover bell jar to exclude light to prevent photosynthesis Do not accept plants convert carbon dioxide to oxygen. 3 max
Question 1
1
Consumption of dark chocolate has been shown to have health benefits. A study was undertaken to see the effects of epicatechin (Epi), a substance in dark chocolate, on the aerobic capacity of leg muscles of mice. A group of adult mice was used to measure the effects of a low dose of Epi given over 15 days. The mice were divided into four groups and given either water or Epi and were either kept idle (no exercise) or made to exercise on a treadmill. After 15 days, the results were analysed. The blood capillary density in leg muscle was measured under the light microscope.
10 marks
Question 1(d)
1(d)
Discuss the effect of exercise on the results of the experiment.
Mediumstructured2 marks
Answer
a. «exercise with» water has no impact b. «exercise with» Epi promotes higher levels of tension for more time c. «exercise with» Epi increases the time to fatigue 2 max
Question 1(e)
1(e)
The scientists tested the expression of four different mitochondrial proteins. The protein samples were taken from leg muscles. The technique that was used to quantify the amount of protein expressed was Western blotting. In this procedure the thickness of the band is an indicator of the amount of protein. Analyse the effect of exercise on the presence of the mitochondrial proteins in the leg muscle.
Hardstructured2 marks
Answer
a. exercise has no/very little effect with water b. exercise with Epi increased III/IV c. «it appears that» exercise with Epi has no/very little effect on II OR Epi relative to water increases all 4 OR exercise has little/no effect on protein I/II d. exercise with Epi «appears to» decrease I 2 max
Question 1(f)
1(f)
Mitochondria are essential for aerobic respiration. Suggest one possible role of the proteins that were studied.
Mediumstructured1 marks
Answer
a. protein channels OR pumps in membranes of mitochondria OR hormone binding sites b. structural/integral/peripheral/glyco/surface proteins c. enzymes/catalysts d. electron transport chain proteins Accept verifiable names of specific membrane enzymes. 1 max
Question 1(g)
1(g)
The scientists concluded that Epi significantly increased aerobic capacity in leg muscle. Evaluate the strength of the evidence provided by all of the data for dark chocolate improving the aerobic capacity of athletes.
HardEssay3 marks
Answer
Limitations: a. study done on mice and may not apply to humans b. levels of Epi administered in experiment may exceed levels in a sample of dark chocolate OR levels of Epi administered in experiment may have different levels in a sample of dark chocolate OR chocolate may have other components with unknown effects on aerobic capacity c. mitochondrial proteins may not improve aerobic capacity Strengths: d. data supports as dark chocolate contains EPI e Epi improves capillary density and would therefore increase aerobic capacity f. Epi improves fatigue resistance g. Epi in combination with exercise improves it further h. Epi increases mitochondrial proteins therefore/presumably increasing aerobic capacity OWTTE 3 max
Question 1
1
The oxygen consumption rate of the fish Oplegnathus insignis was examined in a respirometer at three different water temperatures and at four different body masses.
5 marks
Question 1(a)
1(a)
Suggest how the oxygen consumption rate is determined using this apparatus.
Mediumstructured2 marks
Answer
a. the data logger measures the differences in oxygen concentration OR the oxygen concentration is measured before and after the water passes through the respirometer b. over time c. the mass of fish needs to be measured 2 max
Question 1(b)
1(b)
State the relationship between body mass and the oxygen consumption of fish.
Easystructured1 marks
Answer
greater body mass, less consumption of oxygen OR indirect/negative relationship
Question 1
1
Edible insects have been a part of traditional human diets in many countries. For example, crickets are insects commonly eaten in Asia and Africa. Many studies have looked at the prospects of raising insects on a commercial scale for direct human consumption as food or indirectly by feeding insects to farm animals. One factor to consider is which organisms are most efficient at converting the feed they eat into animal protein that can be consumed. A study compared the percentage of mass that was edible in two common farm animals and in crickets.
12 marks
Question 1(d)
1(d)
Birds and mammals maintain constant body temperature despite considerable losses of body heat to the environment. In insects such as mealworms, body temperature is variable and is often the same as the temperature of the environment or only slightly above it. Analyse the data in the bar charts, using this information.
Mediumstructured2 marks
Answer
a. cell respiration required to generate heat (lost to environment) to maintain body temperature b. birds/chickens and mammals/cattle carry out cell respiration at higher rate than insects c. «chickens/cattle therefore» generate more \(\mathrm{CO}_{2}\) per kg protein produced d. «chickens/cattle» need more food/land area to produce body mass e. feed conversion ratios are lower in mealworms/insects/cold blooded animals as they do not need to maintain a constant body temperature (accept converse)
Question 1
1
Arabidopsis is a small flowering plant in the mustard family (Brassicaceae) that is widely used in basic research. It has a short life cycle, flowers quickly producing a large number of seeds and is easy to cultivate. It forms a circle of leaves known as a rosette that lies close to the soil. Flowers form at the end of short stems. A study was carried out of differences in development between Arabidopsis plants grown in long days ( 16 hours light, 8 hours dark) or short days ( 8 hours light, 16 hours dark). The sixth leaf (L6) to emerge in the rosette of each plant was used in all investigations. New leaves are initiated by the meristem and go through four stages as they develop. - Stage 1 (S1) - rapid cell division - Stage 2 (S2) - cell division has ceased, cell expansion continues - Stage 3 (S3) - decreasing cell expansion rate - Stage 4 (S4) - leaf growth complete The start of each stage of leaf development for plants grown in long days and short days is shown above the first graph.
0 marks
Question 1(c)
1(c)
Leaves were removed from Arabidopsis plants that had been grown in long day and short day conditions and the concentration of starch within them was measured. This was done both at the end of the day (D) and at the end of the night (N) in each of the four stages of development (S1, S2, S3, S4). Discuss the evidence provided in the bar chart for the hypothesis that plant leaves use up starch reserves for cell respiration during the night.
Mediumessay2 marks
Answer
a. lower starch levels at end of night in all stages b. lower starch levels at end of night in both plants grown in short day and long days;; c. no evidence that starch is being used for respiration OR starch may have been exported/stored in other tissues/example tissue «rather than used in respiration» 2 max
Question 1(d)
1(d)
0 marks
Question 1(d)(i)
1(d)(i)
For each of the stages, identify whether the starch concentration at the end of the day is higher in the leaves grown in long day or short day conditions.
Easystructured1 marks
Answer
higher in plants grown in short days in S1 and higher in plants grown in long days for all other stages/S2, S3 and S4 Candidates must mention all stages for the mark.
Question 1(d)(ii)
1(d)(ii)
Suggest reasons for the difference in end of day starch concentrations in stage 2 (S2) for the plants grown in long days and short days. To account for the observed phenotypic and metabolic differences, researchers analysed mRNA transcript data. They found certain transcripts over-represented in Arabidopsis plants grown in long days (dark grey) compared with the amount expected due to chance. Other types of transcripts were over-represented in Arabidopsis plants grown in short days (light grey).
Mediumstructured2 marks
Answer
a. leaves in plants grown in long day receive longer period of light / more leaf surface area so more photosynthesis occurs resulting in more starch b. plants in short days using starch to produce more leaves/for growth/S2 a period of rapid increase in number of leaves Accept vice versa. Accept vice versa.
Question 1
1
An experiment on aerobic respiration was performed using a plant in a pot containing fertile soil. The apparatus was set up as shown in the diagram. Sodium hydroxide and limewater (calcium hydroxide) are both alkaline solutions. Limewater goes cloudy when carbon dioxide is bubbled into it.
0 marks
Question 1(a)
1(a)
State the purpose of lime water in flask B.
Easystructured1 marks
Answer
to check there is no carbon dioxide (left in the air)/show any carbon dioxide present; Do not accept absorb carbon dioxide
Question 1(c)
1(c)
Suggest a suitable control for this experiment.
Mediumstructured1 marks
Answer
using the same apparatus without a plant OR cover the whole plant with a plastic bag; Do not accept a controlled variable