ESS topic 2 ecology exam-style questions

define the term niche

the role a species plays in an ecosystem, including how it obtains food, interacts with other organisms, and responds to abiotic factors

distinguish between primary and secondary succession

primary succession: starts on bare, inorganic surfaces (e.g. volcanic rock); no soil or organisms.

secondary succession: occurs in an area where the community has been cleared but soil remains (e.g. after a fire)

explain how a climax community is reached during succession

- gradual colonisation by more complex species

- changes in abiotic environment due to pioneer species

- increased biodiversity and stability

evaluate the importance of succession in maintaining ecosystem stability

succession allows ecosystems to recover and stabilise; increase biodiversity; maintains nutrient cycles; may resist invasive species. Can be slow or interrupted

explain the concept of the ecological niche, including reference to a named example

niche includes habitat, food source, reproduction, interactions. Example: bees pollinate flowers and collect nectar - role in ecosystem

discuss the effects of competition between species in an ecosystem

competition can reduce resources available, exclude species, lower population sizes. Intraspecific (within the same species) vs interspecific (between different species) competition

explain how the principle of competitive exclusion affects biodiversity

competitive exclusion: no two species can occupy the exact same niche. Leads to niche differentiation or species extinction - reduced biodiversity in some cases. But may increase diversity through specialisation

distinguish between gross primary productivity (GPP) and net primary productivity (NPP)

GPP: total amount of energy captured via photosynthesis

NPP: energy remaining after respiration (available to consumers)

NPP = GPP - respiration

using an example, explain how productivity varies over time using a named ecosystem

tropical rainforest has high NPP year-round, tundra has low NPP due to low sunlight. Seasonal changes e.g. spring surge in productivity

discuss how knowledge of productivity can help in managing natural resources

knowing productivity helps manage agriculture, forestry, fisheries. Helps determine carrying capacity, sustainable yield