Theory question 103
Ecosystem and Ecological Factors(a) (i) List three components of an ecosystem (ii) Describe briefly the interaction among the components named in (a) (i).
(b) List three major steps that are usually taken in studying plants and animals in a community.
(c) State the importance of each of the following in a population and explain how each affects the growth of a population; (i) competition; (ii) pathogens; (iii) water.
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(a)(i) Producers, consumers, decomposers (and/or the non-living environment: soil, water, air, light)
(ii) Producers make food by photosynthesis using light, CO₂ and water; consumers feed on producers or other consumers; decomposers break down dead bodies and wastes, returning nutrients to the soil for producers; energy flows and nutrients cycle
(b) Any three: mapping the area/habitat; sampling (quadrats, transects, traps); collecting and identifying specimens; measuring physical factors; recording and analysing data
(c)(i) Competition for limited food, space, light – weaker ones die or emigrate, so growth slows and the population is kept in check
(ii) Pathogens cause disease, increasing deaths and reducing reproduction – population falls
(iii) Water is needed for all life processes; plentiful water allows growth and increase; shortage (drought) causes death and population decline
In (c) give both the importance and the effect on population size for each factor.