Ecological Scale
Species, population, community, ecosystem, habitat, and niche describe different levels of organisation in ecology.
Lesson 3:
Ecological
Definitions
and Factors
Master the core language of ecology, separate abiotic from biotic factors, and practise soil-analysis calculations for CSEC Biology.
Section
A
Objectives
2.2/2.3
Quiz
35 marks
Ecology: Actors and Architects
Use the video to connect the key ecological terms with the abiotic conditions that shape where organisms live.
Study Guide Summary
Key ideas for CSEC Biology questions on ecological definitions and environmental factors.
Species
A species is a group of organisms that can breed together to produce fertile offspring.
Niche
A niche is the role a species fulfils, including its trophic level and relationships with other species.
Abiotic Factors
Abiotic factors are non-living features such as light intensity, temperature, rainfall, soil pH, salinity, and mineral ions.
Biotic Factors
Biotic factors are influences organisms have on each other, including food, disease, predation, and competition.
Soil Properties
Soil water content, water holding capacity, air content, oxygen, carbon dioxide, and pH affect survival in soil habitats.
Lesson Flashcards
Tap each card to check the answer before attempting the quiz.
Core Ecological Terms
A group of organisms that can breed together to produce fertile offspring.
Individuals of the same species living within a habitat.
The scientific study of organisms and their surroundings or environment.
All the different organisms that live together in a particular place.
A biological community together with all the abiotic factors that influence those organisms.
The role fulfilled by a species in an ecosystem, including feeding level and relationships with other species.
The specific place where an organism lives and obtains the resources it needs to survive.
Abiotic and Biotic Factors
All the non-living features of an ecosystem that influence the organisms in the community.
Latitude, altitude, climate, temperature, water, oxygen, carbon dioxide, light, rainfall, soil depth, soil pH, soil water content, and mineral ion content.
All the influences that organisms in a community have on each other.
Food, disease, predation, and competition for food, water, and living space.
Specific Abiotic Effects
Soil pH influences which plants and animals can survive in a soil habitat.
Light provides energy for photosynthesis and affects the distribution and behaviour of photosynthetic organisms.
Temperature affects the rate of internal chemical reactions, so maximum and minimum temperatures influence survival and distribution.
Salinity is salt content. Changes in water pH or salinity can affect organisms such as clams and corals that form calcium carbonate shells or skeletons.
Soil Characteristics
Water content is the actual amount of water in a soil sample. Water holding capacity is the volume of water that remains after water drains through soil.
Oxygen is needed for respiration by plant roots and soil-dwelling organisms.
Carbon dioxide is needed for photosynthesis by microscopic plants and algae in the upper, lighted soil layers.
Self-Assessment Quiz
Complete all sections. Use the feedback to revise your definitions and calculation method.