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Enviro First Semester Study Guide

Terms in this set (24)

Identify two reasons why biomass tends to be smaller at higher trophic levels
1. Energy loss (respiration/heat/entropy/movement/metabolism/excretion)
2. Not all biomass is discovered/captured/eaten/edible
OR 10% Rule (10% of energy passed on, 90% lost)
Describe one method for estimating the biomass of primary producers
-Sampling: use random/stratified sampling using quadrats to determine total number of producers in a community
-OR Extrapolating: multiply the average dry weight of the individuals by the estimated number of producers
Explain how the process of succession might lead to changes in the productivity of trophic levels in this system
-Early stages of succession: primary productivity is low (not as many resources) which leads to low secondary productivity
-Middle stages: as environment gets more complex, primary productivity increases leading to a bigger food source for secondary consumers, so secondary productivity increases
-High GPP/GSP, Low NPP/NSP
Suggest why the population of snakes (secondary consumers) might increase of all the foxes (tertiary consumers) were killed
Because the removal of foxes would lead to a decrease in the snakes' predators, so the snakes (preys) can increase
Explain (two reasons) why biodiversity is lower in a desert ecosystem than in a tropical rainforest
1. In desert, water is limiting, which leads to lower productivity and higher competition between species
2. In tropical rainforest, there are many sources of food and water, leading to lower competition and higher productivity
Using Figure 7, (1) Identify energy source A, (2) State the process in living organisms that releases heat energy to B, (3) State the group of organisms at C that feed on dead plants, animals and feces.
1. sunlight/solar radiation/insolation
2. respiration
3. decomposers/invertebrates/bacteria/fungi
Suggest why the quantity of energy transferred decreases along the food chain
Most energy entering is lost to the environment as heat/respiration/waste as it moves from lower to higher trophic levels in the food chain
Explain how entropy is increased by each energy transformation that takes place in the food chain
Entropy is a measure of the degree of disorder/chaos or randomness in a system. In respiration, a high proportion of energy is converted to heat, which is a more disordered form of energy (so entropy increases)
With reference to Figure 8, state the type of scale used on the y-axis
log/logarithmic
With reference to Figure 8, identify two reasons why Species A is probably a K-strategist but Species B is more likely to be an R-strategist
-Species A has fewer deaths at a young age than Species B, and they live longer than Species B
-K-strategists tend to be longer lived
State a density-dependent factor that might affect the size of a named animal population
-Supply/availability of food sources (ex: rodents) may affect consumers such as snakes.
-the higher the trophic level, the more competition there is for food
Explain how the size of the named animal population may eventually reach a steady-state equilibrium (be able to sketch)
-Rodents could be affected by food shortages/disease/predation, so population falls below equilibrium
-Snakes would then have less food, so their population decreases
-No snakes lead to less predation on rodents, so rodent population increases/recovers (negative feedback)
Ecosystem
a community of independent organisms and the physical environment they inhabit
State an example of a flow within a named ecosystem
-water flow through a river ecosystem
-flow of sunlight through forest ecosystem (used with photosynthesis)
Eutrophication
-the enrichment of a water body (lake, stream, etc.) by increased nutrient inputs (phosphates and nitrates)
-depletion of oxygen content of water
-leads to development of algae, could be accelerated by human activity
Using Figure 2, identify Process A and Process B
A- (agricultural) run-off/surface flow/nutrients entering lake
B- leaching/sedimentation/seepage
Suggest one agricultural source and one non-agricultural source that may account for high phosphate levels
Agricultural: fertilizers (containing phosphates and nitrates), animal waste, manuer
Non-agricultural: detergents (domestic), industrial effluent, sewage
Suggest how an environmental manager may reduce the impact of eutrophication
-identify the potential sources of eutrifying materials (detergents, fertilizers, effluents)
-put in strategies for removing these pollutants
-educate water source users about eutrophication problems
List three factors assessed in an EIA
-number of species
-diversity
-habitat type and abundance
Even though an EIA promises environmental damage, give two reasons why a project may continue
-financial gain
-environmental benefits
-benefits to humans
Give two reasons why satellite images might be good for measuring change in an area
-easy/cheap to public
-can track image over time
What are the differences between an S curve and a J curve? (be able to draw)
S Curve-capped at carrying capacity
J Curve-exponential
Succession
change in an ecosystem over time
Using Figure 1, (1) state what variable would be good for the x-axis and (2) outline what would happen to soils as the ecosystem changes from A to B
1. time
2. richer/more nutrients, holds more water, deeper
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