Global Challenges | OCR GCSE Combined Science Biology, Foundation tier (J250)

Global Challenges

233 questions
13 subtopics
Paper 2 (Biology)
Paper 2 (Biology)

Global Challenges is examined in Paper 2 (Biology).

It covers field investigations, and human impact on ecosystems, maintaining biodiversity, monitoring conservation and ecotourism, selective breeding and genetic engineering, health, disease, and types of disease, interactions between diseases, and how they spread, reducing the spread of disease, and named examples, white blood cells, antibodies and platelets, non-specific defences and the immune system, vaccines, medicines and aseptic technique, developing new medicines, and non-communicable disease, treating cardiovascular disease, and lifestyle factors, cancer, and the use of stem cells in medicine and gene technology in medicine, and the human genome.

Sample questions from Global Challenges

Answer each one closed book first, then open the answer.

Field investigations, and human impact on ecosystems

What is a pooter and how does it work?

Show the answer
A small jar with two tubes for collecting insects; the user sucks on one tube so the insect is drawn through the other into the jar, and gauze stops it being swallowed.
Maintaining biodiversity, monitoring conservation and ecotourism

What is ecotourism?

Show the answer
Tourism that lets visitors see wildlife in its natural habitat while limiting damage to that habitat and returning money to local people.
Health, disease, and types of disease

Explain why someone with a poor diet is more likely to catch an infectious disease.

Show the answer
A shortage of nutrients weakens the immune system, so fewer white blood cells and antibodies are made to fight the pathogen.
Interactions between diseases, and how they spread

Explain why a single infected plant can lead to the loss of an entire field of crop.

Show the answer
The plants are close together and genetically very similar, so the pathogen spreads rapidly and every plant is equally susceptible.
White blood cells, antibodies and platelets

What is an antibody, and which cell produces it?

Show the answer
A protein that binds to a specific antigen on a pathogen; it is produced by a lymphocyte.
Non-specific defences and the immune system

Explain why it takes several days to recover from an infection met for the first time.

Show the answer
The few lymphocytes that fit the antigen must first divide many times before enough antibodies are made, and the pathogen multiplies during that time.
Developing new medicines, and non-communicable disease

Explain why developing a new medicine takes many years and costs a great deal.

Show the answer
Each stage of testing must be completed and approved before the next can begin, and most substances tested fail and are abandoned.
Treating cardiovascular disease, and lifestyle factors

What is the modal class of a frequency table?

Show the answer
The class interval with the highest frequency.

The 13 subtopics

One subtopic is one session. Work down the list.

Subtopic	What it covers	Questions
Field investigations, and human impact on ecosystems	Random sampling with quadrats and belt transects, estimating plant numbers from quadrat counts and animal populations by capture-recapture with its assumptions, collecting with pooters and sweep nets, using a dichotomous key, how land use, monoculture and hunting reduce biodiversity, captive breeding, nature reserves and habitat conservation, positive human interactions, and the mean, median, mode and percentiles of survey results.	23
Maintaining biodiversity, monitoring conservation and ecotourism	The benefits of high biodiversity to people and why it makes an ecosystem stable, why international conservation agreements are hard to reach, why conservation schemes must be monitored and why that is difficult, what ecotourism is, and how it can both conserve and damage a habitat.	8
Selective breeding and genetic engineering	What selective breeding is and how it improves wheat and dairy cattle, why it reduces genetic variation and raises disease risk, inbreeding and its health problems, the economic and ethical arguments, what genetic engineering and a genetically modified organism are, why a bacterial gene works in a plant, insect-resistant maize, beta-carotene rice and bacterial insulin, and the benefits, risks and objections of modified crops.	23
Health, disease, and types of disease	What health and disease are and how they relate, other factors such as diet, exercise and stress, how a weak immune system or poor diet raises the risk of infection, links between physical and mental ill health, communicable and non-communicable diseases with their causes and examples in humans and crops, the four types of pathogen, and why crowding spreads disease.	16
Interactions between diseases, and how they spread	How the virus that causes AIDS attacks lymphocytes and makes tuberculosis more likely, how human papillomavirus can lead to cervical cancer and how cases are reduced, how pathogens pass between people, vectors such as mosquitoes, how pathogens spread between plants and through a crop, how fast bacteria multiply, and estimating the number of infections from a sample.	16
Reducing the spread of disease, and named examples	Reducing the spread of disease by hygiene, isolation, vaccination and controlling insect vectors, identifying pathogens by antigen and DNA tests and plant diseases by symptoms, removing diseased plants, influenza, athlete's foot and Salmonella food poisoning, how the virus that causes AIDS spreads and progresses, preventing sexually transmitted infections, and tobacco mosaic virus, barley powdery mildew and crown gall in plants.	17
White blood cells, antibodies and platelets	How a phagocyte engulfs and digests a pathogen and is adapted to do so, antibodies made by lymphocytes and why each fits only one pathogen, antitoxins, what platelets are, how blood clotting keeps pathogens out, and why too few platelets raise the risk of infection.	8
Non-specific defences and the immune system	Non-specific defences including the skin, nose hairs and mucus, cilia in the airways, stomach acid, tears and scabs, why burns lead to infection, what antigens are, how lymphocytes make antibodies that clump pathogens for phagocytes, why a first infection takes days to recover from, memory cells and immunity, and why one strain of a virus may not protect against another.	16
Vaccines, medicines and aseptic technique	What a vaccine contains and how it gives immunity, what antibiotics, antivirals, antiseptics and painkillers do and do not do, why drugs that kill viruses are hard to make, antibiotic resistance, aseptic technique with flamed loops, alcohol, autoclaves and taped dishes kept at 25 °C, and testing antiseptics with paper discs on a bacterial lawn, including calculating the area of clear zones.	25
Developing new medicines, and non-communicable disease	Where early medicines came from, testing new medicines for toxicity, efficacy and dose in preclinical and clinical trials, placebos and double-blind trials, why development is slow and costly, the interacting causes and risk factors of non-communicable diseases such as coronary heart disease, bronchitis, cirrhosis, type 2 diabetes and cancer, and peer review and how trial results are published and communicated.	22
Treating cardiovascular disease, and lifestyle factors	Lifestyle changes, statins, stents, bypass operations and valve replacements for cardiovascular disease with their advantages and risks, how exercise, saturated fat, alcohol and smoking affect non-communicable disease, why disease patterns differ between places, the rise of type 2 diabetes and the costs of disease, and using bar charts, histograms, modal classes, percentages and scatter diagrams to judge correlation and cause.	27
Cancer, and the use of stem cells in medicine	What cancer and tumours are, why changes in genes cause uncontrolled division, benign and malignant tumours and how secondary tumours form, risk factors and why early detection helps, the benefits and risks of stem cell treatments, bone marrow transplants, embryonic stem cells and the ethical objections to them, therapeutic cloning, and why transplants are rejected and how rejection is reduced.	16
Gene technology in medicine, and the human genome	Insulin made by gene technology, gene therapy for disorders such as cystic fibrosis with its practical difficulties and risks, the benefits and the ethical and privacy concerns of genetic testing and changing embryos, sequencing the human genome, and how it helps predict disease risk, target drugs to a patient's genome, trace inherited disorders and develop new medicines.	16

Global Challenges is 233 of the 806 questions in the guide.Get the guide, £7

How the guide is worked

Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.

Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.

Read the full method, the return schedule and the research behind it.