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QLDBiologyQuick questions
Unit 3: Biodiversity and the interconnectedness of life
Quick questions on Abiotic and biotic factors, tolerance ranges and ecological niche (QCE Biology Unit 3)
10short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What are abiotic factors?Show answer
Abiotic factors are the non-living, physical and chemical conditions of the environment.
What are biotic factors?Show answer
Biotic factors are the influences other organisms have on the species in question.
What are tolerance ranges?Show answer
Every species has a range of values of each abiotic factor within which it can survive and reproduce. Plotted as a tolerance curve (performance against the factor), the curve is bell-shaped with the following zones:
What is ecological niche?Show answer
A species' ecological niche is its multidimensional role in an ecosystem: where it lives, when it is active, what it eats, what eats it, what it requires and what it provides. The niche is summarised along several axes.
What is fundamental niche?Show answer
The full set of conditions under which the species can survive and reproduce, with no competitors or predators present.
What is realised niche?Show answer
The actual subset occupied once species interactions are factored in. Competition usually shrinks the niche; facilitation can expand it.
What is competitive exclusion principle?Show answer
Two species with identical niches cannot coexist indefinitely; the better competitor displaces the other. Coexistence requires niche differentiation (different resources, different times, different microhabitats).
What is q1?Show answer
Distinguish between fundamental niche and realised niche, giving one biotic factor that can reduce the realised niche. [3 marks]
What is q2?Show answer
A graph shows growth rate of _Aedes aegypti_ mosquito larvae against water temperature from 15 to 40 degrees Celsius; growth peaks at 28 degrees Celsius and reaches zero at 12 and 36 degrees Celsius. Identify the optimum and tolerance range and predict the effect of a 2 degrees Celsius warming on Cairns mosquito distribution. [3 marks]
What is q3?Show answer
Refer to a Brisbane River saltmarsh. (a) Identify two abiotic and two biotic factors influencing crab abundance. (b) Predict the effect of urban run-off raising water nitrate.