Edexcel iGCSE Biology-5.5 Abiotic & Biotic Factors- Study Notes- New Syllabus
Edexcel iGCSE Biology-5.5 Abiotic & Biotic Factors- Study Notes- New syllabus
Edexcel iGCSE Biology-5.5 Abiotic & Biotic Factors- Study Notes -Edexcel iGCSE Biology – per latest Syllabus.
Key Concepts:
5.5 understand how abiotic and biotic factors affect the population size and distribution of organisms
Factors Affecting Population Size & Distribution
🔹 Introduction
Population size = number of individuals of a species.
Distribution = where organisms are found.
Both are influenced by abiotic (non-living) and biotic (living) factors.
📌 Abiotic Factors (non-living)
Physical & chemical conditions of the environment. They affect survival, reproduction, and where species can live.
- Temperature → polar bears in cold regions, reptiles more active in warmth.
- Light intensity → plants need sunlight; shady vs open areas.
- Water availability → cacti in deserts, frogs near ponds.
- Soil type & minerals → sandy vs clay soils affect plant growth.
- Oxygen/CO₂ levels → aquatic organisms need dissolved oxygen.
📌 Biotic Factors (living)
Interactions between organisms. They influence survival, competition, and distribution.
- Predation → prey numbers controlled by predators.
- Competition → plants compete for light, water, minerals, animals for food, mates, territory.
- Disease & parasites → can reduce population size.
- Human activity → deforestation, hunting, conservation.
📊 Summary Table
| Factor Type | Examples | Effect on Population/Distribution |
|---|---|---|
| Abiotic | Temperature, water, light, soil | Limit where organisms can survive/grow |
| Biotic | Predation, competition, disease | Control numbers and interactions of species |
📝 Quick Recap
Abiotic = non-living → temperature, light, water, soil, gases.
Biotic = living → predators, competition, disease, humans.
Together they control where organisms live & how many survive.