EduNinjaThe diagram shows levels of DDT, a pesticide, in an aquatic food web in Lake Kariba, Africa. Numbers represent ppm (parts per million) of DDT in fat tissue.
Justify the observation that the crocodile has a higher mean DDT level than the cormorant or tigerfish.
Discuss the impact of overfishing in Lake Kariba and how sustainable harvesting of resources can be assessed.
Populations evolve by natural selection due to interactions with the environment and other species within the ecosystem.
Explain how the loss of a keystone species affects an ecosystem.
Laboratory-scale mesocosms were built to investigate the effect of very small contaminants (nanoparticles) on ramshorn snails (Planorbarius corneus).
State two variables measured by the probes.
1:
2:
Suggest one advantage of using a mesocosm in this type of research.
Outline the requirements for sustainability within a sealed mesocosm.
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.
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. be marked.
What is exchanged between a sealed mesocosm and the surrounding external environment?
Energy
Water
Air
Nothing can pass
Which factor(s) would be expected to vary in a closed terrestrial mesocosm?
I. Carbon content
II. Temperature
III. Biomass
I only
I and II only
II and III only
I, II and III
A simple sealed terrestrial mesocosm was set up to demonstrate that natural ecosystems can be sustainable over long periods of time.
What indicates that the mesocosm is still sustainable after several months?
Wastes are constantly recycled.
The diversity of living organisms increases.
Energy is conserved.
The mass of carbon increases.
Beavers (Castor fiber) have been reintroduced into many European countries. They cut down trees and use them as a source of food as well as for building their homes and dams.
Beavers are a keystone species. Outline the importance of keystone species.
Outline two methods of restoration of natural processes in ecosystems by rewilding, other than reintroducing a keystone species.
1.
2.
Which is not essential in a viable mesocosm?
Light source
Autotroph
Saprotroph
Herbivore
Satellite imagery has been used for many years in the Amazon rainforest to monitor deforestation. Annual deforestation can be calculated using data from several satellites that have varying levels of accuracy. The graph shows the area of the Amazon rainforest that was deforested each year from 2001 to 2019, calculated using satellite images.
Calculate the percentage decrease from the maximum deforestation area on the graph to the area in 2019.
Other researchers have studied deforestation in relation to the size of new clearings (deforested areas) within forests. The graphs show the numbers of new clearings smaller than 1 hectare and larger than 1000 hectares, between 2001 and 2013. 1 hectare is .
Forest clearings smaller than 1 hectare
Forest clearings larger than 1000 hectares
Suggest a reason that the number of small clearings increased while the number of large clearings decreased greatly since 2004.