Question 1
1
The biodiversity of insects worldwide is in decline. Destruction of habitats, pollution and climate change have contributed to the decline in global insect populations and to the extinction of insect species. A comprehensive literature review was carried out to determine the annual global rate of decline in insect species. The graph shows the results for three major orders of terrestrial insects and the total decline in insect biomass worldwide.
0 marks
Question 1(d)
1(d)
One species of the order Hymenoptera is the buff-tailed bumblebee (Bombus terrestris), which feeds on pollen and nectar obtained from specific plants. Destruction of preferred habitats has affected the size of bumblebee populations and for survival, bumblebees have to feed on pollen from other available plant habitats. To simulate different pollens, researchers fed bumblebees on eight diets consisting of a mixture of proteins and lipids in different ratios (P:L). The bumblebees also had access to sucrose. There was no restriction on the amount of each food the bumblebees could consume. The chart shows the mean daily mass of food eaten for eight diets with different P:L ratios. Identify in how many of the diets sucrose was the greatest mass of food consumed.
Mediumstructured1 marks
Answer
5;
Question 1(e)
1(e)
Compare and contrast the results for the 1:1 and the 1:10 P:L diets.
Mediumstructured2 marks
Answer
a. in both a greater mass of sucrose was eaten (than of the P: L mixture) OR the total mass eaten by both groups is the same/very similar; b. the mass of sucrose eaten in the 1: 10 mixture diet is greater than in the 1: 1 diet OR the mass of the P: L mixture eaten in the 1: 10 is less than in the 1: 1; Accept vice versa for all answers
Question 1(i)
1(i)
Suggest with a reason which P: L diet is closest to the normal diet of these bumblebees.
Hardstructured1 marks
Answer
10:1 diet as this has the highest survival rate (after 7 days); Reason must be given
Question 1(j)
1(j)
Discuss whether these studies show that habitat destruction can affect global bumblebee numbers.
HardEssay2 marks
Answer
a. habitat destruction removes the plants/flowers/natural food source of the bees; b. bees have to look for other food sources; c. many of these alternative sources of food are not suitable for bee survival OR pollen with a different proportion of protein to lipid would reduce survival; d. no control where bees are fed their normal diet is included; e. simulation is not using natural pollen / habitat; OR sample size is too small to make conclusions; Accept other reasonable discussion using the data 2 max
Question 1
1
Remote sensing satellites are used to monitor the Earth's ecosystems. One measure of ecosystem status is leaf area index (LAI), which is the total area of leaves in square metres per square metre ( \(\mathrm{m}^{2} \mathrm{~m}^{-2}\) ) of the Earth's surface. The graph shows LAI estimates, calculated using data from the Global Inventory Monitoring and Modelling System (GIMMS), during the period from 1981 to 2011. The data points are monthly averages in four latitudinal zones in the northern hemisphere.
15 marks
Question 1(d)
1(d)
The data in the graph show a long-term trend in global LAI.
3 marks
Question 1(d)(ii)
1(d)(ii)
Global ecosystem modelling suggests that most of the change in LAI is due to increases in atmospheric carbon dioxide. Explain how rising atmospheric carbon dioxide ( \(\mathrm{CO}_{2}\) ) concentration could cause the observed change in LAI. The 2015 Paris Agreement sets out an international framework for avoiding dangerous climate change. A key aspect is conserving and enhancing sinks of greenhouse gases, including forests. Free air carbon dioxide enrichment (FACE) experiments are being used to investigate whether increases in atmospheric \(\mathrm{CO}_{2}\) concentration will cause biomass increases in existing forests. Three FACE experiments have been running for at least ten years in young, developing forests. Photosynthesis rates are measured in 25 to 30 m diameter plots. In control plots, carbon dioxide concentrations remain at current atmospheric levels (ambient CO2). In treatment plots, the CO2 concentration is raised by 50 % (elevated \(\mathrm{CO}_{2}\) ). The table gives some details of these experiments and the highest annual net primary production recorded during the period of the experiment. Net primary production is the mass of carbon absorbed and fixed by photosynthesis in plants that is not released due to plant respiration.
Mediumstructured2 marks
Answer
ii a. more photosynthesis (with higher carbon dioxide concentration); b. more plant growth/more (plant) biomass/more leaves/more plants; If the answer focuses on greenhouse effect or global warming, do not award mpa, but mpb can be awarded if one of the alternatives is included in the answer. [2]
Question 1(e)
1(e)
State the effect of elevated \(\mathrm{CO}_{2}\) on net primary production in these young, developing forests.
Easystructured1 marks
Answer
increases it/higher (maximum annual net primary production); The answer must be referring implicitly or explicitly to NPP. [1]
Question 1(f)
1(f)
Outline one benefit of conducting similar FACE experiments in multiple locations. In each forest, there are two or three trial plots per CO2 treatment. The bar chart shows the allocation of carbon from net primary production to different parts of the trees in these trial plots.
Mediumstructured1 marks
Answer
check whether trend is confirmed/replicated/not specific to some forests OR investigate worldwide effects (of rising carbon dioxide) OR (check whether results are affected by) differences in tree species/types of tree/soil types/rainfall/temperature/climate/latitudes/conditions/biome/ecosystem; Reject general answers about reliability or anomalies. [1]
Question 1(g)
1(g)
Evaluate the evidence from the bar chart that increases in carbon dioxide cause increases in carbon storage in young, developing forests.
Hardstructured3 marks
Answer
a. more carbon stored/allocated (by the tree as a whole) with elevated carbon dioxide; b. evidence (from the bar chart) is strong (for the trend/hypothesis); c. all elevated plots have more carbon stored than all ambient plots in all sites/no overlap; d. more/most carbon allocated to wood (in stems and roots) with elevated carbon dioxide; e. more carbon allocated to narrow roots/leaves with elevated carbon dioxide; f. narrow roots increase most in Oak Ridge; g. most increase in wood (in stems and roots) in Rhinelander and Duke; h. much/more variation between plots at Oak Ridge (than at Rhinelander and Duke); i. no error bars so significance of differences is uncertain; Accept mpd and mpe if the answer refers only to Rhinelander and Duke. Allow mph if the answer describes an anomaly at Oak Ridge that does not follow the trend seen in Rhinelander and Duke. [3 max]
Question 1
1
There were widespread and intense wildfires in Southeast Australia during the summer season from November 2019 to January 2020. Estimates have been made of carbon dioxide emissions from these fires based on satellite monitoring data. The bar chart shows estimates made by five different research programmes: GFED, GFAS, QFED, FEER and FINN. The table shows other statistics for comparison. 2019-2020 constrained by satellite. Nature (597), pp. 366-369. https://doi.org/10.1038/s41586-021-03712-y.]
structured13 marks
Question 1(a)
1(a)
The highest estimate of \(\mathrm{CO}_{2}\) emitted from wildfires in Southeast Australia between November 2019 and January 2020 is 820 Tg , from the FEER research programme. State the lowest estimate. Programme: Estimate:
Easystructured1 marks
Answer
QFED is 660; Allow 650 to 680 Tg
Question 1(b)
1(b)
Using the data in the table, comment on the magnitude of the wildfires in Southeast Australia from November 2019 to January 2020. In addition to carbon dioxide, carbon monoxide and other gases, the wildfires emitted smoke. Smoke is an aerosol of solid particles and liquid droplets suspended in air. The complex mixture of chemicals in this aerosol includes black carbon (soot) and compounds of nitrogen, phosphorus and iron. This aerosol absorbs light, allowing its optical density and movement to be assessed by satellite monitoring. Much of the smoke from the wildfires in Southeast Australia in 2019-2020 was carried eastwards across the South Pacific Ocean. The study area shown in the map was affected by the smoke. Australian wildfires. Nature (597), pp. 370-375. https://doi.org/10.1038/s41586-021-03805-8.] The graph shows the optical density of the air and the chlorophyll concentrations of the water in this study area. The concentration of chlorophyll is proportional to the density of phytoplankton (photosynthetic bacteria and algae) in the water. Daily measures of aerosol optical density (AOD) 8-day mean chlorophyll concentration in 2019-2020
Mediumstructured3 marks
Answer
a. larger than annual ( \(\mathrm{CO}_{2}\) ) emissions for the whole of Australia; b. larger than all fossil fuel emissions for the whole of Australia in a typical year; c. extreme/intense/OWTTE; d. (much) larger than the typical emissions of 9 Tg (for Nov to Jan) in SE Australia; 3 max
Question 1(c)
1(c)
Identify two differences between aerosol optical density (AOD) in the months before the wildfires and during the period of wildfires.
Mediumstructured2 marks
Answer
a. higher AOD during the wildfire period than before; b. more fluctuation/more spikes in AOD during the wildfire period than before; Accept converse for both.
Question 1(d)
1(d)
Using the data in the graph, distinguish between phytoplankton populations in 2019-2020 and in previous years. Samples of air carrying the aerosol from the wildfires were filtered at Mount Wellington on Tasmania, and the amounts of iron and levoglucosan on the filters were measured. Levoglucosan is produced by combustion of carbohydrates such as starch and cellulose, so is used as a chemical tracer for biomass burning. Bars on the graph show amounts of levoglucosan, and datapoints show amounts of iron.
Mediumstructured3 marks
Answer
a. rises/increases in phytoplankton/chlorophyll in Nov to Jan 2019-20 whereas it falls/decreases in previous years; b. higher in Nov to Jan 2019-20 than previous years; c. large fluctuations in 2019-20 versus /smoother/less variation/steadier in previous years; d. a correct mathematical discussion of the magnitude; Both parts required in mpa. 3 max
Question 1(e)
1(e)
Explain the conclusions that can be drawn from the data in the graph.
Hardstructured2 marks
Answer
a. levoglucosan/iron concentrations increase from Nov 27, 2019 to Jan 17, 2020; b. (because)both are released during combustion/burning; c. wildfires released large/significant amounts/concentrations of iron because it is a component of smoke; d. levels of levoglucosan and iron differ after Jan 17 because iron remains in the atmosphere longer than the levoglucosan; 2 max
Question 1(f)
1(f)
In the South Pacific Ocean, chlorophyll production and growth of phytoplankton are usually limited by a low concentration of iron in the water. Suggest a hypothesis for the cause of the unusual pattern of phytoplankton growth during the summer of 2019-2020.
Mediumstructured2 marks
Answer
a. conditions/observations in the hypothesis; b. reasoning in the hypothesis; Examples: iron from wildfires was deposited in the oceans; which increases phytoplankton growth; OR deposition of iron caused growth/bloom; iron being a limiting factor for growth of phytoplankton; OR increased level of iron in water allows increased production of chlorophyll; so, phytoplankton growth is high; Accept other reasonable hypotheses that respond to the question.
Question 1
1
Fish play a key role in the functioning of temperate shallow lakes. They affect nutrient cycles and interactions between trophic levels. Studies were done to compare fish community structure and dynamics between shallow lakes in Denmark (temperate) and in Uruguay (subtropical). The following organisms were found in one of these lakes: - macrophytes - large aquatic plants - zooplankton - microscopic animals - piscivorous fish (eat other fish) - algae - aquatic plants - omnivorous fish (eat plants and animals) - planktivorous fish (eat plankton) - phytoplankton - microscopic plants - herbivorous fish (eat plants)
structured11 marks
Question 1(a)
1(a)
3 marks
Question 1(a)(ii)
1(a)(ii)
Suggest one way that fish can increase the nutrient content in shallow lakes.
Mediumstructured1 marks
Answer
a. increase through excretion (of minerals/urea)/feces/waste products; b. increase CO_2 through breathing/(cell) respiration; c. increase through decay (of dead fish); d. fish that eat flies and bring that matter into the lake; 1 max
Question 1
1
Phytoremediation is the use of plants to extract and remove contaminants or lower their bioavailability (amount available to organisms) in soil. Tree species are used because they have deep root systems and fast growth rates that enable them to take up contaminants in larger amounts than plants such as grasses. The diagram shows the steps in phytoremediation in plants. A study in North Carolina, USA, used different tree species for phytoremediation of groundwater contaminated by leaked petrochemicals. Four types of hybrid poplar clones (Populus sp.), loblolly pine (Pinus taeda) and willow (Salix sp.) were planted from 2006 to 2008, and measurements were made of trees in 2010 and 2012. The graph shows percent survival of hybrid poplar clones, loblolly pine and willow trees on the phytoremediation site.
structured15 marks
Question 1(f)
1(f)
Calculate the percentage change in BTEX from February 2007 to July 2013.
Mediumstructured1 marks
Answer
-99.6\% / -99.56\%;
Question 1(g)
1(g)
Determine with evidence from the bar chart which type of contaminant is removed at a greater rate from the soil between February 2007 and August 2007. Dioxane is another environmental contaminant that is difficult to remove from contaminated sites. Hybrid poplar cuttings (Populus deltoides x nigra) were grown. Once they had rooted, seven cuttings were transferred to individual reactors, as shown in the diagram. Five cuttings were as shown and two were controls. One control had the leaves removed, and the stem and roots of the other control were not immersed in the nutrient solution. The concentration of dioxane that remained in the nutrient solution was measured daily.
Mediumstructured1 marks
Answer
TPH because the (absolute) decrease (in mass) is greater (than BTEX) OR TPH because it decreases by \(5170(\mu \mathrm{~g})\) whereas BTEX decreases by \(402(\mu \mathrm{~g})\) OR BTEX because the percentage decrease (in mass) is greater (than TPH) OR BTEX because \% decrease (in mass) is 87.6\% whereas with TPH it is 27.6\%;
Question 1(j)
1(j)
Using all the data, evaluate the use of trees in phytoremediation.
HardEssay3 marks
Answer
a. ( \(1^{\text {st }}\) study shows) some trees/pines/willows are killed by contaminants/are not useful for phytoremediation; b. (2nd study shows) transpiration (can be) affected/increased/decreased by petroleum fuel/contaminants; c. (3rd study shows) trees removed TPH/BTEX/hydrocarbons/petrochemicals/ petroleum/petroleum fuel (from contaminated soil); d. (4th study shows) roots (of poplars) absorb dioxane; e. (4th study shows) leaves/transpiration needed for dioxane uptake; f. (4th study shows) leaves (can) release dioxane/petrochemicals into the air (polluting it); 3 max
Question 1
1
Albatrosses (belonging to the Family Diomedeidae) are large marine birds that can live for up to 50 years and feed at the highest trophic level. They have a very large wing span (up to 3 m ) and can use winds to travel long distances over water while foraging for food at sea. However, their survival and reproduction are threatened by both climate change and accidental death. This may be caused by being caught in the lines or nets of commercial fishing vessels that are in their foraging areas. A 31-year study analysed population data of three different species: the wandering albatross (Diomedea exulans), the grey-headed albatross (Thalassarche chrysostoma) and the black-browed albatross (T. melanophris). All three species breed in colonies on the same island in the Antarctic.
structured0 marks
Question 1(e)
1(e)
Krill are tiny marine crustaceans that have a very important role in the Antarctic food chains. Krill are a major source of food for many marine species, including whales, seals, fish and albatrosses. The graph shows the survival of adult grey-headed albatross related to krill density between 1996 and 2011.
structured0 marks
Question 1(e)(i)
1(e)(i)
Calculate the percentage increase in krill density from 1996 to 2002.
EasyCalculation1 marks
Answer
300\%; Calculation not needed.
Question 1
1
Common bottlenose dolphins, Tursiops truncatus, are marine mammals of temperate and tropical oceans throughout the world, where they feed on fish, squid and crustaceans. Research has been carried out on a population of these dolphins in Sarasota Bay, Florida. The table shows the mean sea surface temperature in Sarasota Bay and catch per unit effort (CPUE) in winter and summer. A large CPUE indicates it would take little effort for the dolphin to catch a lot of prey.
structured10 marks
Question 1(a)
1(a)
0 marks
Question 1(a)(i)
1(a)(i)
Calculate the difference between summer and winter sea surface temperatures.
Easystructured1 marks
Answer
\(6.1^{\circ} \mathrm{C}\);
Question 1(a)(ii)
1(a)(ii)
Calculate summer CPUE as a percentage of winter CPUE. \%
Easystructured1 marks
Answer
600 / 600.2 / 600.18; Accept answers within the range 600 to 600.2 .
Question 1
1
Freshwater mussels are molluscs found in rivers and lakes worldwide. They filter water for food and remove algae, bacteria and detritus, improving the water quality. Researchers in South Korea placed mussels (U. douglasiae) in water containing cyanobacteria, a type of photosynthetic bacteria that cause eutrophication of rivers and lakes. The density of cyanobacteria is proportional to the concentration of chlorophyll in the water. The filtration rate by mussels can be determined by measuring the change in concentration of chlorophyll at various time intervals. The experiments were conducted with two different levels of dissolved oxygen in the water (DO). In the control experiment, no mussels were present and the DO level was \(9.0 \mathrm{mg} \mathrm{L}^{-1}\). Key: - DO \(0.5 \mathrm{mg} \mathrm{L}^{-1}\) - DO \(9.0 \mathrm{mg} \mathrm{L}^{-1}\) - Control
Data Response0 marks
Question 1(c)
1(c)
Suggest a reason for the change in the chlorophyll concentration of the control during the experiment.
Mediumstructured1 marks
Answer
increasing in number as the cyanobacteria/phytoplankton were reproducing/ growing;
Question 1(j)
1(j)
Using all the data, deduce with reasons whether the water quality of the River Thames changed from 1964 to 2020.
HardData Response2 marks
Answer
a. (the first piece of data shows) that mussels improved water quality because they filtered / quality goes down when mussels are absent and cannot filter; b. (the second piece of data) shows changes in the distribution of mussels over time so water quality may be changing OR the distribution changes indicate that the water quality became more suitable for some mussels and less suitable for others; c. (the third piece of data shows) shows a decrease in the number/density over time and that might indicate lower survival rates due to poor water quality OR decrease in the number/density of mussels over time indicates cleaner water/less food (because there is no need for filtering); d. other factors/legislation may lead to changes in water quality OR not only the quantity of mussels determines water quality; 2 max
Question 1
1
Male Lepidoptera (butterflies and moths) commonly drink from pools of water or from moist soil. This behaviour, called puddling, was investigated in an undisturbed area where male tiger swallowtails, Papilio glaucus, had been seen puddling. Four successive sets of experiments were performed under similar conditions of temperature and humidity. In each set, equal samples of sand were spread out evenly on trays and then treated differently. Except for one dry sample (in the first set), all others were saturated with a different liquid. Results of the observations are given in the table below.
12 marks
Question 1(a)
1(a)
Identify the dissolved element always present in the three samples with most puddling time.
Mediumstructured1 marks
Answer
sodium/Na
Question 1(f)
1(f)
Suggest one reason for puddling behaviour in male Lepidoptera.
Mediumstructured1 marks
Answer
puddling provides needed sodium/Na because their (larval) food does not supply enough sodium/Na; sodium/Na needed for neural activity; greater flight/neural activity in males than in females; Accept other reasonable suggestions.
Question 1
1
The grey partridge (Perdix perdix) is a species of bird that is found on farmland. Sparrowhawks (Accipiter nisus) and buzzards (Buteo buteo) are birds of prey that kill and feed on birds, including grey partridge. The number of grey partridges in a region of southern England was monitored from 1970 to 2004. The numbers of sparrowhawks and buzzards, seen from sampling positions during regular observation periods, were counted. The results are shown in the graph below.
0 marks
Question 1(d)
1(d)
Suggest a conservation measure that would be most likely to prevent the extinction of grey partridges from southern England.
Mediumstructured1 marks
Answer
limit/ban shooting of grey partridge; train shooters to recognize difference between grey partridge and other species of partridge; protect/restore habitat of grey partridge; promote captive breeding of grey partridge (for release into ecosystem); remove birds of prey/foxes depending on laws;