Key term
OCR A-Level Biology H420
Cell Structure
Biological Molecules
Nucleotides and Nucleic Acids
Enzymes
Biological Membranes
Cell Division, Cell Diversity and Cellular Organisation
Exchange Surfaces
Transport in Animals
Transport in Plants
Communicable Diseases, Disease Prevention and the Immune System
Biodiversity
Classification and Evolution
Communication and Homeostasis
Excretion as an Example of Homeostatic Control
Neuronal Communication
Hormonal Communication
Plant and Animal Responses
Topic overviewTropisms and plant responses to stress and herbivoryPlant hormones and their commercial usesThe nervous system and the brainReflex actions and the knee jerk reflexFight or flight and the control of heart rateThe structure of skeletal muscleThe neuromuscular junction and the sliding filament model
Photosynthesis
Respiration
Cellular Control
Patterns of Inheritance
Manipulating Genomes
Cloning and Biotechnology
Topic overviewNatural plant cloning and taking cuttingsMicropropagationAdvantages and disadvantages of plant cloningAnimal cloning: embryo twinning and nuclear transferAdvantages and disadvantages of animal cloningMicroorganisms in food productionAseptic techniqueFermentation and its conditionsThe microbial growth curveImmobilised enzymes
Ecosystems
Populations and Sustainability
Practical Skills and Mathematical Requirements
Populations and Sustainability
- 5 subtopics
- 8 things to know
- Components 02 and 03
What Populations and Sustainability covers
Populations and sustainability closes Module 6. It covers what sets the size of a population and its carrying capacity, predator and prey cycles, competition within and between species, the difference between conservation and preservation, sustainable timber and fishing, and how human impacts are controlled.
Where it is assessed
Components 02 and 03
Module 6 is examined on Biological Diversity, then the unified paper.
Check the OCR specification ↗The 5 subtopics
Each one has its own page.
- Population size and limiting factorsBirth rate, death rate, immigration and emigration, and the abiotic and biotic limiting factors that set the carrying capacity of an environment.Open →
- Predator-prey cycles and competitionThe lag between predator and prey numbers and the pattern it produces on a graph, and interspecific and intraspecific competition.Open →
- Conservation and preservationWhat separates conservation from preservation, and the economic, social, cultural and ethical arguments made for protecting an ecosystem.Open →
- Sustainable timber production and fishingCoppicing, selective cutting, replanting and rotational felling, and the quotas, mesh sizes, closed seasons and exclusion zones used in fishing.Open →
- Human impacts and how they are controlledHabitat destruction, pollution, overexploitation and invasive species, and the legislation, protected areas, habitat restoration and captive breeding that respond.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Process
Explain predator-prey population cycles.
Process
How can fishing be made more sustainable?
Key term
What is meant by carrying capacity?
Key term
Define interspecific competition.
Key term
Define conservation in an ecological context.
Key term
What is meant by preservation of an ecosystem?
Process
How do human activities reduce populations, and how are these impacts controlled?
Take Populations and Sustainability further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Conservation vs Preservation
Conservation: active management allowing resources to remain available for future generations. Preservation: protection from human interference and exploitation.
Questions from this topic
Each one with the model answer underneath.
- 1
How does birth rate affect population size?
Model answer
Birth rate increases population size by adding new individuals to the population.
- 2
How does death rate affect population size?
Model answer
Death rate decreases population size by removing individuals from the population.
- 3
What is the effect of immigration on population size?
Model answer
Immigration increases population size by adding individuals that move into the population from elsewhere.
- 4
How does emigration influence population size?
Model answer
Emigration decreases population size by removing individuals that leave the population to live elsewhere.
- 5
Define the term limiting factor.
Model answer
A limiting factor is any factor that restricts the growth, abundance, or distribution of a population when in short supply.
- 6
What is meant by carrying capacity?
Model answer
Carrying capacity is the maximum population size that an environment can sustain indefinitely given the available resources.
What is inside Levo
Six ways to work the same material.
Populations and Sustainability revision questions
- What does Populations and Sustainability cover in OCR A-Level Biology?
- 5 subtopics: population size and limiting factors, predator-prey cycles and competition, conservation and preservation, sustainable timber production and fishing and human impacts and how they are controlled. Each one has its own page with questions and model answers.
- How is Populations and Sustainability organised?
- By the OCR H420 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Populations and Sustainability, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
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