This mini-lesson covers OCR B6 — Global challenges: sampling & monitoring ecosystems, human impact, food security, health & disease, pathogens and the immune system, drug development and biotechnology.
Work through each screen, answer the questions as you go and collect ⭐ stars. Watch for the Higher tier flags. Press Start when you're ready.
Sampling & monitoring ecosystems
Sampling & monitoring
We monitor ecosystems to spot changes and pollution:
Quadrats (placed randomly) and transects (along a line) estimate populations and how they change.
Indicator species reveal pollution — e.g. lichens and mayfly larvae only survive in clean air/water.
Scale up the mean per quadrat to estimate the whole population; more, random samples = more reliable.
Indicator species: their presence or absence is a quick, cheap sign of environmental quality.
Quick check
What is an indicator species?
?Why are lichens useful as indicator species?
Human impact & food security
Human impact & food security
A growing human population increases demand and impact:
Human impact: deforestation, pollution, and greenhouse-gas emissions reduce biodiversity and change the climate.
Food security is having enough safe food for everyone. It is threatened by a rising population, changing diets, pests, disease and climate change.
Ways to improve yield: fertilisers, pest control, and biotechnology (e.g. GM crops).
Sustainability: we must increase food production without permanently damaging ecosystems or biodiversity.
Health · pathogens
Health, disease & pathogens
Health is a state of physical and mental wellbeing. Diseases can be:
Communicable (infectious) — caused by pathogens that spread between organisms.
Non-communicable — not spread; e.g. many cancers, heart disease.
The four pathogen groups: bacteria (e.g. Salmonella), viruses (e.g. measles, HIV), fungi (e.g. rose black spot) and protists (e.g. malaria, spread by mosquitoes).
Bacteria vs viruses: bacteria release toxins that make you feel ill; viruses invade cells and reproduce inside them, damaging the cell. Antibiotics kill bacteria but not viruses.
Quick check
What do antibiotics kill?
?A patient has a viral infection. Why won't antibiotics help?
The immune system
The immune system & vaccination
White blood cells defend the body against pathogens by:
Phagocytosis — engulfing and digesting pathogens.
Producing antibodies that lock onto specific pathogens.
Producing antitoxins that neutralise toxins.
Vaccination: a harmless form of the pathogen (antigen) is introduced, so white blood cells make antibodies and memory cells. If the real pathogen invades later, the response is faster and larger — you are immune.
Herd immunity: if enough people are vaccinated, the pathogen can't spread easily, protecting those who aren't vaccinated.
Quick check
How does a vaccine work?
?How does a vaccine protect you from a disease?
Match it
Match each pathogen to its group
Tap a disease, then its pathogen type.
Statement
Answer
Drug development
Developing new drugs
New drugs are tested in stages before use:
Preclinical — tested on cells, tissues and then animals.
Clinical trials — tested on healthy volunteers (for safety) then patients (for safety and effectiveness), finding the best dose.
Placebo and double-blind trials (neither doctor nor patient knows who gets the real drug) reduce bias.
Why so thorough? testing checks a drug is safe, effective and given at the right dose before it reaches patients.
Quick check
What is a double-blind trial?
?In a double-blind drug trial, who knows which patients receive the real drug?
Biotechnology
Biotechnology & genetic engineering
Biotechnology uses living organisms to make useful products:
Genetic engineering — transferring a gene from one organism to another (e.g. inserting the human insulin gene into bacteria so they make insulin).
GM crops — modified for pest resistance or higher yield to help food security.
Enzymes and microorganisms are used to make foods, medicines and fuels.
Evaluate GM: benefits include higher yields and insulin production, but there are concerns about long-term effects, ethics and reduced biodiversity.
Sort it
Sort each into its group
Tap each item, then tap which theme it belongs to.
🦠 Fighting disease
🌾 Food & environment
🧫 Biotechnology
Recap
The big ideas to know
Monitoring: quadrats, transects & indicator species (e.g. lichens)
Food security: enough safe food; threatened by population, pests, climate