Abiotic Factors (AQA GCSE Biology): Revision Notes

7.1.2 Abiotic Factors

Key Abiotic Factors and Their Effects on Communities

1. Light Intensity

• Light is essential for photosynthesis in plants.
• The rate of photosynthesis affects plant growth, which in turn influences the availability of food and shelter for other organisms.
• Impact: Changes in light intensity can affect plant populations and the species that depend on them.

2. Temperature

• Temperature influences the rate of enzyme activity and, consequently, metabolic processes in organisms.
• Impact: Fluctuations in temperature can affect reproduction, growth rates, and seasonal behaviours such as migration and hibernation.

3. Moisture Levels

• Water is crucial for the survival of all living organisms as it is involved in various biological processes.
• Impact: Low moisture levels can limit plant growth, leading to a decrease in food and habitat for animals.

4. Soil pH and Mineral Content

• Soil pH affects the rate of decay and the availability of mineral ions, which are vital for plant nutrition.
• Different plant species have varying requirements for soil pH and nutrients.
• Impact: Changes in soil composition can affect plant distribution and health, influencing the entire ecosystem.

5. Wind Intensity and Direction

• Wind affects the rate of transpiration (the movement of water from roots to leaves) in plants.
• Transpiration is important for temperature regulation in plants and the distribution of water and minerals.
• Impact: High wind intensity can increase water loss, affect plant growth, and influence seed and pollen dispersal.

6. Carbon Dioxide (CO₂) Levels

• CO₂ is necessary for photosynthesis in plants.
• Different organisms may thrive in varying CO₂ concentrations.
• Impact: Increased CO₂ levels can enhance plant growth but also affect the distribution of species that require specific CO₂ levels.

7. Oxygen Levels for Aquatic Animals

• Oxygen levels in water can vary greatly, unlike in air, due to temperature and water movement.
• Most fish and other aquatic organisms require a high concentration of dissolved oxygen for respiration.
• Impact: Low oxygen levels can lead to decreased survival rates for aquatic life, affecting the entire aquatic food chain.