Exam Questions Flashcards
Give two advantages of using re-introduction of beavers from northern Europe to as a strategy for conservation in the UK
- increase in freshwater habitats
- ensure the beavers are well adapted to their environment
- reduce flooding
Give two reasons why people may be concerned about illegal, unregulated re-introduction of beavers
- they may compete with other present specie
- they may carry diseases
- destruction of existing habitat
- may not have prepared these habitat properly
Give two factors that scientists would have to consider when planning the successful re-introduction of beavers
- that the beavers are disease free
- that this is approved by local neighbourhoods
Explain how deforestation can directly affect the planetary boundary for climate change
- large volumes of CO2 is released during deforestation either for decaying burnt trees or machinery
- this travels to the atmosphere enhancing the greenhouse effect raising global temperatures affecting the climate change boundary
- deforestation also reduced the CO2 uptake by the plant
Explain how the growth curve would differ if a total count had been used to measure the population density
the exponential curve would start sooner - then only a stationary phase count will remain constant as dead and live bacteria are both counted
Evaluate the effectiveness of using this minimum mesh size in allowing the recovery of the cod population?
- would have very little effect
- bigger mesh size will still catch older fish
- Egg production reaches it’s maximum after 12 years
- Older fish produce many more eggs
- Eggs from older fish far more likely to develop into embryos
The diagram below shows the flow of energy through an ecosystem.
Sun
1 × 106 solar energy
autotroph
heterotroph
heterotroph
8000 800 160 32
heterotroph
Figures represent kJ m–2 yr –1
Using the diagram, explain what is meant by the flow of energy through an ecosystem and why
energy is lost at each stage.
Explain why the efficiency of transfer might change at each stage.
Suggest ways by which farmers can improve the efficiency of the transfer between each level.
Energy flow and loss at each trophic level
- Energy from the sun converted into energy in organic molecules by plants / GPP
- Plants break down sugars by respiration / NPP
- Energy in the form of organic molecules is then passed from 1 organism to another along the food chain when organisms are eaten
- Energy lost by plants as green light is reflected
- Energy is lost by animals in respiration
- Egestion - energy is left in the form of organic molecules
Efficiency of transfer
- Cellulose and lignin are not easy to digest
- Large loss by egestion
- Proteins and fats easy to digest - very little energy lost by egestion
- Higher energy lost by urea
- High respiratory rate energy for movement
Improvement
- Growing plants with a higher GPP
- Breeding animals with higher efficiency
- Animal feeds with less cellulose
- High energy supplements
- Reduce respiration by reducing movements and keeping buildings warm
- Disease Free
Given that one effect of global warming appears to be more flooding in the UK, discuss
why the government is encouraging landowners to preserve and re-instate such meadows
in certain areas by compensating them for the loss of productive farm land.
- Land retains water
- Which is released slowly into the rivers
- Reducing flash floods
- There is a conflict of interest between loss of farmland and conservation farmers need to be compensated for loss of land
- conservation to maintain biodiversity
Human activity and bacteria play a vital role in making nitrogen available to increase
the yield of crops.
Explain the ways that human activity and bacterial action can influence nitrogen
availability and the negative impacts that this may have on the environment.
Farmers can improve soil fertility through the addition of manure / dead animal and plant material - this is decomposed by bacteria providing a slow release of nitrogen
Farmers can supply soluble fertiliser which can be taken up by the plants faster
Farmers can plant leguminous plants to increase nitrate levels
Leguminous plants have Rhizobium in their root nodules
Nitrosomonas convert NH4+ -> NO2-
Nitrobacter convert NO2- -> NO3-
Ploughing and field draining encourages aerobic conditions and discourages encourage anaerobic conditions -> this favour nitrification and disfavours denitrification
Improving soil fertility by the addition of organic & inorganic fertiliser has a negative impact if it leaches into water sources - eutrophication
the electrical input needed to produce inorganic fertilisers is very large and would lead to increased carbon dioxide and consequently global warming
Explain why scientists consider that the destruction of sea otter populations could
contribute to an increase in global warming.
- As sea otters are eaten sea urchins are not eaten so kelp population decreases
- less photosynthesis
- less CO2 absorbed
- carbon dioxide is a greenhouse gas
Explain why an increase in global warming could have been a contributory factor in
the planetary boundary for biodiversity being crossed.
Sea temperature increases above what is suitable for organisms
Atmospheric temperature increases faster than organisms can adapt
Thermal expansion of water leads to higher sea levels resulting in habitat destruction
Explain one advantage and one disadvantage of expressing the change in the
number of breeding pairs as a percentage.
Advantage - can compare different starting numbers
Disadvantage - if starting numbers are small than any change results in a large % change
With reference to the terms GPP and R, explain why the productivity of an
ecosystem can be expressed in terms of absorption of carbon dioxide or by the
release of carbon dioxide.
- CO2 absorbed by photosynthesis GPP
- CO2 released in respiration NPP
