Topics 1 & 8
Which is an example of negative feedback? A. Loss of vegetation leading to soil erosion leading to further loss of vegetation. B. A decline in a large predator population after they have eaten most of their prey population. C. Melting of permafrost in the tundra due to climatic change leading to further release of methane, causing further change. D. Unsustainable slash and burn agriculture practices in tropical rain forests.
B
Net Primary Production is the amount of energy
A. produced from ‘alternative’ sources in developing countries.
B. fixed in an ecosystem by photosynthesis.
C. fixed in an ecosystem by photosynthesis, minus the losses due to respiration by producer organisms. D. fixed by the herbivores in an ecosystem.
C
Which statement is correct?
A. Elephants are K-strategists because they have a low population growth rate.
B. r-strategists tend to reproduce late and have few offspring.
C. The population size of a species is only genetically controlled.
D. All plants are K-strategists because they have limited ability to compete.
A
Which statement about soils is correct?
A. Clay soils are capable of retaining more moisture than sandy soils.
B. Soils form rapidly in some climates and thus soil is often regarded as a renewable resource.
C. Irrigation of soils prevents salinization.
D. Loam soils are generally less productive than either clay or sandy soils.
A
Which factor greatly increases the likelihood of photochemical smog forming over a city?
A. Low altitude
B. High rainfall
C. High traffic densities
D. Short daylight hours
C
Define "ecological footprint"
area of land and resources required to sustainably provide all resources at the rate at which they are consumed
With reference to named examples, distinguish between a primary and secondary pollutant.
a primary pollutant is one which is active on emission / directly impacts the environment;
eg CO2 is released from burning fossil fuels and actively contributes to global warming / CFCs are released from aerosols and actively contribute to ozone depletion;
a secondary pollutant is one formed from a primary pollutant through physical/chemical change;
eg CO2 combines with sea water to form carbonic acid that leads to impacts on calciferous shelled organisms or corals / NOx combines with water to form acid precipitation / NO2 forms PAN/ozone (that contributes to photochemical smog).
The data below refers to the world population in 1998. Crude birth rate = 23 per thousand Crude death rate = 9 per thousand The Natural Increase Rate was:
(23-9)/10= 1.4
To estimate the population of animal S, the students marked the eight individuals that they found and returned them to the ecosystem. One week later, the students caught 20 individuals of animal S, of which five were marked. Estimate the size of the population of animal S.
20X8/5=32
Lincoln Index
Outline the role of mangroves and tropical rainforests in the mitigation of climate change
mangroves/tropical rainforest mitigate climate change/reduce CO2 in the atmosphere by absorbing CO2;
mangroves sequester/remove a greater amount of CO2 (per unit area) than the other ecosystems/tropical forest / mangroves are more efficient at storing carbon than tropical forests / mangroves are more effective carbon sinks than tropical forests;
tropical forest hold more carbon in their living biomass / mangroves hold more carbon in the soil;
both tropical rainforest and mangroves store the highest amount of CO2 within their living biomass for their own ecosystem category;
mangroves hold approximately 1500 metric ton carbon per hectare / tropical forest hold approx 230 metric ton carbon per hectare;
State three reasons why global energy use continues to rise
growth in human population; increase in affluence/wealth; technological developments; increased travel; increased industrialization; increased international trade/globalization;
Evaluate the use of incineration as an alternative to recycling for the management of solid waste.
PROS cheaper/costs; reduces amount of waste more quickly than recycling; ash may be used as a raw material (e.g. road building); can deal with waste that cannot be recycled; can kill disease agents; can reduce the toxicity of waste; can produce energy; CONS residues still require disposal; ash from combustion can be toxic; may produce undesirable air pollutants (such as carbon dioxide/GHGs/linked to health problems); transportation concerns/costs; capacity limitations; reluctance of some owners/operators/residents; it does not reduce resource use as recycling does;
Compare and contrast limiting factors in S and J population curves.
the initial gradient of both S and J-curves is low due to limiting factors / low numbers reproducing; initially exponential increase / positive feedback occurs in both S and J-curves; in S-curves, limiting factors eventually slow the population growth/maintain equilibrium/plateau (the population has reached its carrying capacity); eg limited food / increased predation/disease / accumulation of wastes / competition; limiting factors may be density dependent / provide negative feedback mechanism to maintain this equilibrium; in J-curves, limiting factors eventually lead to rapid decline/population crash; eg seasonal climate change / disease / overexploited food resources (typically r-selected species); while both S and J curves may be influenced by density independent factors, it is the density-dependent factors that bring about an equilibrium in S-curves;