ecological niches

Outline what is meant by the niche concept (2)

a. the role of an organism in its environment
OR
functional position of an organism in its environment ✔

b. includes «spatial» habitat AND feeding activities AND interactions with other species in the community ✔ All required.

c. no two species can occupy the same niche ✔

d. a niche can be fundamental or realized ✔

The processes of photosynthesis and respiration have some factors in common and others differ. Compare and contrast both processes for specific factors. (7)

both:

• have membrane-bound organelles adapted to their function

• generate ATP

• used (excited) electrons transferred between carriers on the membranes

differences

• P: solar energy is converted to chemical energy, R: organic/chemical energy is converted to usable energy

• P: occurs in chloroplast whereas R occurs in mitochondria

• P fixes CO2 whereas R produces CO2

• P produces O2 whereas R used O2

Outline the role of fungi in nutrient cycling (2)

a. act as saprotrophs/decomposers ✔ 

b. rot/feed on/break down organic matter/food/organisms 
OR
return nutrients trapped in organic matter to the cycle/soil ✔

• Do not accept detritivores

Compare and contrast fundamental and realized niche of a species. (2)

a. both describe the habitat/role/relationship occupied by a species ✔

b. the fundamental niche is the potential role of a species in its ecosystem and realized niche is the actual role
OR
the fundamental niche depends on the adaptations of a species whereas the realized niche is limited by competition/predation
OR
realized niche is ‹usually› smaller than fundamental niche ✔

Outline the principle of competitive exclusion.

a. no two species can occupy the same niche;

b. competition between them would cause one species to drive the other out
OR
one of the two species would need to adapt and evolve accordingly;