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.

Compare and contrast the results for the 1:1 and the 1:10 P:L diets.

Suggest with a reason which P: L diet is closest to the normal diet of these bumblebees.

Discuss whether these studies show that habitat destruction can affect global bumblebee numbers.

The data in the graph show a long-term trend in global 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.

State the effect of elevated $\mathrm{CO}_{2}$ on net primary production in these young, developing forests.

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.

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.

Evaluate the evidence from the bar chart that increases in carbon dioxide cause increases in carbon storage in young, developing forests.

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:

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

Identify two differences between aerosol optical density (AOD) in the months before the wildfires and during the period of wildfires.

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.

Explain the conclusions that can be drawn from the data in the graph.

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.

Calculate the percentage change in BTEX from February 2007 to July 2013.

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.

Using all the data, evaluate the use of trees in phytoremediation.

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.

Suggest a reason for the change in the chlorophyll concentration of the control during the experiment.

Using all the data, deduce with reasons whether the water quality of the River Thames changed from 1964 to 2020.

Identify the dissolved element always present in the three samples with most puddling time.

Suggest one reason for puddling behaviour in male Lepidoptera.

Suggest a conservation measure that would be most likely to prevent the extinction of grey partridges from southern England.