B4.2.1— Ecological Niche as the Role of a Species in an Ecosystem

Define a Niche

A niche is the role or position a species occupies within an ecosystem. It includes how the species interacts with its environment, other organisms, and the resources it uses for survival and reproduction.

Factors that Determine the Niche of a Species

  1. Habitat: Physical location where the species lives.
  2. Diet: Type of food it consumes (herbivore, carnivore, omnivore).
  3. Behavior: Activity patterns (e.g., nocturnal or diurnal).
  4. Reproductive Role: How and when it reproduces.
  5. Interactions: Competition, predation, and symbiotic relationships.
  6. Abiotic Factors: Tolerance to temperature, light, water, soil pH, etc.

Compare Niche Generalists and Specialists

Feature Niche Generalists Niche Specialists
Definition Species that can survive in a wide range of conditions. Species that have very specific requirements.
Diet Varied diet; adaptable. Specific, limited diet.
Habitat Wide range of habitats. Restricted to specific habitats.
Survival More resilient to environmental changes. Vulnerable to habitat or resource loss.
Example Raccoons, cockroaches. Koalas (depend on eucalyptus leaves).

B4.2.2— Oxygen Requirements of Different Organisms

Type Definition Example
Obligate Anaerobes Cannot survive in oxygen; rely on anaerobic respiration. Clostridium botulinum (causes botulism).
Facultative Anaerobes Can survive with or without oxygen; switch between aerobic and anaerobic respiration. Escherichia coli (E. coli).
Obligate Aerobes Require oxygen for aerobic respiration and survival. Humans, Mycobacterium tuberculosis.

B4.2.3— Photosynthesis as the Mode of Nutrition

Energy and Carbon Sources in Photosynthesis