OCR GCSE Biology B (Twenty First Century)
OCR GCSE Biology B B2.1 What are the causes of disease? Exam Questions
Free OCR GCSE Biology B exam questions for B2.1 What are the causes of disease?, with a mark scheme for every pack. Covers Health and disease, communicable and non-communicable disease, pathogens including bacteria, viruses, fungi and protists, how pathogens spread and viral replication.
B2.1 What are the causes of disease? exam questions
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About OCR GCSE Biology B B2.1 What are the causes of disease?
B2.1 opens chapter B2, Keeping Healthy, by sorting diseases by cause. You need to distinguish communicable diseases, caused by pathogens that can pass between organisms, from non-communicable diseases, and name examples of human and plant diseases caused by bacteria, viruses, fungi and protists. You should explain how each pathogen spreads and how it damages the host, including how viruses use host cells to reproduce. This sets up immunity in B2.2, preventing spread in B2.3 and diagnosis in B2.4. Examiners often give unfamiliar disease data and ask you to identify the pathogen type or suggest how it spreads.
What you need to know
- Health and disease Health is a state of physical and mental wellbeing. Disease can be communicable (caused by a pathogen and passed on) or non-communicable (not passed between people, such as heart disease).
- Types of pathogen Pathogens include bacteria (e.g. tuberculosis), viruses (e.g. HIV, tobacco mosaic virus), fungi (e.g. athlete's foot, ash dieback) and protists (e.g. malaria).
- How pathogens spread Pathogens spread by air (droplets), water, food, direct contact, body fluids and vectors such as mosquitoes. Plant pathogens spread through soil, wind, water and insects.
- How pathogens cause harm Bacteria multiply and may release toxins that damage cells. Viruses reproduce inside host cells and damage or destroy them.
- Viral replication A virus attaches to a host cell and injects its genetic material, which takes over the cell to make new virus particles. In the lytic cycle the cell bursts to release them; in the lysogenic cycle the viral genes are inserted into the host DNA and stay dormant before becoming active later.
- Diseases interacting Having one disease can increase the risk of another, for example HIV weakens the immune system so people are more likely to develop tuberculosis.
Common mistakes in B2.1 What are the causes of disease?
- Calling viruses cells or saying antibiotics kill them. Viruses are not cells and are not affected by antibiotics.
- Saying malaria is caused by mosquitoes. Malaria is caused by a protist; the mosquito is the vector that carries it.
- Describing non-communicable diseases as caused by microorganisms. They are linked to risk factors such as lifestyle and genes, not pathogens.
- Writing that bacteria invade and destroy cells as viruses do. Bacteria usually damage tissues by releasing toxins.
- Confusing the lytic and lysogenic cycles. In the lysogenic cycle the viral DNA joins the host genome and is copied without immediately bursting the cell.
Try three B2.1 What are the causes of disease? exam-style questions
1. Name the type of pathogen that causes malaria. (1 mark)
Show the mark scheme answer
Protist.
2. A bacterium divides every 20 minutes. Starting with one bacterium, calculate how many bacteria there would be after 2 hours. (2 marks)
Show the mark scheme answer
2 hours is 120 minutes, so 120 / 20 = 6 divisions; 2^6 = 64 bacteria.
3. Describe how a virus reproduces using the lytic cycle. (4 marks)
Show the mark scheme answer
The virus attaches to a specific host cell; it injects its genetic material into the cell; the host cell machinery makes copies of viral genetic material and proteins, which are assembled into new viruses; the cell bursts (lyses), releasing new viruses to infect other cells.
B2.1 What are the causes of disease? FAQs
What does OCR GCSE Biology B B2.1 cover?
It covers communicable and non-communicable disease, the four main types of pathogen with human and plant examples, how they spread and how viruses reproduce.
Which paper is B2.1 examined in?
J257 has two papers at each tier, Breadth in Biology and Depth in Biology, and content from any chapter, including B2, can be assessed on either one. Expect it to be linked to ideas about science and to other chapters.
Which disease examples should I learn for B2.1?
Learn at least one example for each pathogen type, including how it spreads and its symptoms, for both humans and plants, and be ready to apply the same ideas to diseases you have not met.
