What this topic covers
B4: Community level systems has 1 subtopic:
- B4.1 Ecosystems
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GCSE OCR Higher Biology · Topic 4 of 6
B4: Community level systems – GCSE OCR Higher Biology revision notes
Choose a subtopic. Ecosystems, decomposition and biomass transfer. 24 lessons in 1 subtopic.
Revise B4: Community level systems for GCSE OCR Higher Biology, including B4.1 Ecosystems. 24 lessons across 1 subtopic.
24
Lessons
1
Subtopics
B4: Community level systems lessons by subtopic
24 lessons, grouped by subtopic.
B4.1 Ecosystems
- Understanding Ecosystems and Their Organisation
- Competition and Survival in Communities
- Interdependence and Community Stability
- Physical Abiotic Factors in Ecosystems
- Chemical Abiotic Factors and Specialized Environments
- Analyzing the Impact of Abiotic Changes on Communities
- Living Factors Affecting Communities
- Analyzing Changes in Communities
- Types of Adaptations
- Extremophiles and Extreme Environments
- Working with ecological data
- Producers and feeding relationships
- Studying ecosystems and predator-prey relationships
- Material cycling in ecosystems
- The carbon and water cycles
- Microorganisms in material cycling
- Factors Affecting Decomposition and Rate Calculations
- Practical Applications of Decomposition
- Understanding Trophic Levels in Ecosystems
- The Role of Decomposers in Ecosystems
- Understanding Pyramids of Biomass
- Pyramids of Biomass and Energy Transfer
- Why Biomass is Lost Between Trophic Levels
- Calculating Biomass Transfer Efficiency
More in this course
Go back to the full GCSE OCR Higher Biology topic list, or practise this topic with past-paper questions.
Frequently asked questions
What is B4: Community level systems?
Ecosystems, decomposition and biomass transfer. 24 lessons in 1 subtopic.
How do you find the median?
To find the median, arrange all values in ascending order, then take the middle value. The Working with ecological data notes cover this in full.
What is the mode in a data set?
The mode is the value that appears most frequently in a data set; a data set can have no mode, one mode or multiple modes. The Working with ecological data notes cover this in full.
What is precipitation?
Precipitation is water falling from clouds as rain, snow, sleet or hail. The The carbon and water cycles notes cover this in full.
What is biomass?
Biomass is the total mass of living organisms in a given area or volume, measured in grams per square metre (g/m²) or kilograms per hectare (kg/ha). The Understanding Pyramids of Biomass notes cover this in full.
What is a producer in a food chain?
A producer is an organism that synthesises molecules using energy from the environment, usually through photosynthesis, converting light energy into chemical energy stored in glucose. The Producers and feeding relationships notes cover this in full.
What is an apex predator?
An apex predator is a predator at the top of its food chain with no natural predators when fully grown, often a tertiary consumer. The Understanding Trophic Levels in Ecosystems notes cover this in full.
How is a cactus adapted to compete for water?
A cactus has a widespread shallow root system to collect rainwater quickly, a thick, fleshy stem that stores water for dry periods, and spines instead of leaves to reduce water loss by transpiration. The Competition and Survival in Communities notes cover this in full.
What is interdependence in ecology?
Interdependence is the way species in a community depend on each other for survival needs like food, shelter, pollination and seed dispersal. The Interdependence and Community Stability notes cover this in full.