CSEC Biology • Lesson 3 of 4Ecological Terms & Abiotic Factors · Myers Science Hub Student Centre
CourseCSEC Biology
Practice formatMCQ • Structured • Experimental
Your progress0% complete
Learning objectives
- Distinguish habitat, niche, species, population, community and ecosystem.
- Distinguish abiotic from biotic factors.
- Explain how light, temperature, water, soil pH, mineral content and salinity can affect organisms.
- Interpret ecological data linking an abiotic factor to distribution.
Core notes
Habitat
The place where an organism lives.
Niche
The role of an organism in its ecosystem, including what it uses, where it feeds and how it interacts.
Population
Members of one species living in a particular habitat at the same time.
Community
All the populations of different species living in a habitat.
Abiotic and biotic factors
| Abiotic | Why it matters |
|---|---|
| Light | affects photosynthesis and behaviour |
| Temperature | affects enzyme-controlled reactions and water loss |
| Water availability | affects transport, photosynthesis and survival |
| Soil pH / mineral content / salinity | affects nutrient availability and osmosis |
Biotic factors include food supply, predators, competitors, pathogens and other living organisms. Distribution depends on the combined effects of abiotic conditions and biotic interactions.
Video lesson
Paper 01-style MCQ
1. Which statement best describes a niche?KC • 1
2. Which is an abiotic factor?KC • 1
3. A plant species is found mainly in shaded, damp sites. Which conclusion is most justified?UK • 1
Paper 02-style structured questions
4. Distinguish between a population and a community.UK • 4
Population: members of the same species living in a particular habitat/area (2). Community: all populations of different species living together in that habitat/area (2).
5. Explain TWO ways in which soil conditions can affect plant distribution.UK • 4
Any two explained factors, 2 marks each: pH affects mineral availability; water-holding capacity affects water supply; salinity affects water uptake by osmosis; mineral content affects nutrient supply; aeration affects root respiration.
Experiment-type question
6. Plan an investigation to test whether light intensity affects the distribution of a small ground plant along the edge of a school building.XS/PD • 8
State aim/hypothesis (1); use a line/belt transect or repeated quadrats from shaded to brighter positions (1); measure light intensity at each position (1); count/estimate plant abundance or frequency (1); keep quadrat size and sampling method consistent (1); take repeated samples (1); graph plant abundance against light intensity/distance (1); identify a limitation or confounding factor such as moisture/soil differences (1).