HL Paper 3
The graph shows global CO2 contributions from the use of fuels since 1825. Emissions estimates for the years since 1950 are based on energy data from the United Nations while emissions estimates for years prior to 1950 have been constructed using a variety of sources.
[Source: Boden T ; Marland G ; Andres R J (1999): Global, Regional, and National Fossil-Fuel CO2 Emissions (1751 – 2014)
(V. 2017). Carbon Dioxide Information Analysis Center (CDIAC), Oak Ridge National Laboratory (ORNL),
Oak Ridge, TN (United States). doi:10.3334/CDIAC/00001_V2017]
Calculate the percentage increase in the use of liquid fuels from 1950 to 1975.
%
Referring to the data, compare and contrast the changes in the use of the different fuels between 1950 and 1975.
The worm Branchiobdella italica lives on the external surface of the freshwater crayfish Austropotamobius pallipes. A study was carried out in a river in central Liguria, north-western Italy, of the range of sizes of B. italica found on adult A. pallipes.
Describe the body length frequency of the B. italica worms collected in this study.
The relationship between A. pallipes and B. italica is mutualistic.
A. pallipes feeds on algae and another worm, B. exodonta, lives inside A. pallipes as a parasite. State the trophic level of B. exodonta in this food chain.
Distinguish between mutualism and parasitism, providing another example of mutualism and another example of parasitism.
The larval stage of the fly Eurosta solidaginis develops in the plant Solidago altissima. The larva secretes a chemical which causes plant tissue to grow around it forming a swelling called a gall. The gall provides the developing insect with protection from predators.
The E. solidaginis fly is preyed upon by the parasitic wasp Eurytoma gigantea. The graph shows the relationship between gall diameter and the percentage of flies that avoid predation by E. gigantea.
In order to form galls, the insects choose a location where cell division occurs at a high rate. State the term for a region of rapid cell division within a plant.
Describe the relationship between gall diameter and percentage survival of E. solidaginis.
Explain the concept of directional selection with respect to this example.
Scientists have constructed systems to reproduce the conditions of natural wetlands. The mesocosms below were used to study nutrient removal from water flowing through.
[Source: © 2013. Silviya Lavrova and Bogdana Koumanova (October 2nd 2013). Nutrients and Organic Matter Removal in a
Vertical-Flow Constructed Wetland, Applied Bioremediation – Active and Passive Approaches, Yogesh B. Patil and
Prakash Rao, IntechOpen, DOI: 10.5772/56245. Available from: https://www.intechopen.com/books/applied-bioremediationactive-
and-passive-approaches/nutrients-and-organic-matter-removal-in-a-vertical-flow-constructed-wetland]
Compare and contrast the design of both mesocosms (vertical flow and horizontal flow).
Suggest with a reason which system best reproduces the conditions of the natural environment.
State two variables other than temperature and light that should be controlled in this experiment, in order to discover which system is more effective at removing nutrients from water.
Mean annual chlorophyll concentration was measured in surface water of Narragansett Bay along the Atlantic coast of the USA, from 1971 to 2006. Field data of chlorophyll concentrations are shown below.
Suggest a hypothesis for the trend in the graph.
Mesocosm experiments using water from Narragansett Bay were completed in the laboratory during a six month period. Discuss advantages and limitations of carrying out mesocosm investigations.
An investigation into food web interactions was conducted in mesocosms in the Mediterranean Sea, off the coast of France. The effects of the addition of soil and fish on bacterial populations were tested.
Each of the mesocosms is an open ecosystem. State the property that makes the mesocosms open ecosystems.
Assuming that the populations of bacteria are under bottom-up control, identify the mesocosms in which the bacterial populations will be highest.
Outline top-down effects on the bacteria in the four mesocosms.
Suggest advantages of undertaking this experiment in the sea rather than in the laboratory.