OCR A Level Biology A
OCR A Level Biology A Module 4: Biodiversity, Evolution and Disease Exam Questions
Free OCR A Level Biology A exam questions for Module 4: Biodiversity, Evolution and Disease, with a mark scheme for every pack. Covers pathogens and transmission, plant and animal defences, the immune response, vaccination, biodiversity measurement, classification and evolution.
Module 4: Biodiversity, Evolution and Disease exam questions
3 question packs of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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About OCR A Level Biology A Module 4: Biodiversity, Evolution and Disease
Module 4 of OCR A Level Biology A, Biodiversity, Evolution and Disease, links disease and immunity with the variety of life on Earth. It covers pathogens and how they spread, plant and animal defences, the specific immune response, vaccines and antibiotics, sampling and measuring biodiversity, threats to and conservation of biodiversity, classification and the evidence and mechanism of evolution. It underpins genetics and ecology in Module 6. Examiners commonly ask about phagocytosis, the roles of T and B lymphocytes, Simpson's index calculations, sampling methods, the three-domain system and statistical tests such as Spearman's rank and Student's t-test.
What you need to know
- 4.1.1 Pathogens and defences Bacteria, viruses, protoctista and fungi as pathogens of plants and animals, direct and indirect transmission, plant defences such as callose deposition, and primary non-specific defences in animals including skin, mucous membranes, clotting and inflammation.
- 4.1.1 The immune response Phagocytes, T and B lymphocytes, antibody structure and function, primary and secondary responses, active and passive immunity, vaccination, autoimmune disease, sources of medicines and antibiotic resistance.
- 4.2.1 Biodiversity at habitat, species and genetic level, random and non-random sampling, Simpson's index of diversity D = 1 - sum(n/N)^2, genetic diversity, factors affecting biodiversity, and in situ and ex situ conservation including international agreements.
- 4.2.2 The taxonomic hierarchy, the binomial system, five kingdoms versus three domains, evidence for evolution from fossils, DNA and comparative anatomy, types of variation, anatomical, physiological and behavioural adaptations, natural selection, and examples such as pesticide and antibiotic resistance.
Common mistakes in Module 4: Biodiversity, Evolution and Disease
- Saying antibiotics kill viruses. Antibiotics act on bacterial structures and processes such as cell walls and 70S ribosomes; viruses lack these.
- Writing that bacteria become resistant because they are exposed to antibiotics. Resistance arises by random mutation; antibiotics select for resistant bacteria, which survive and reproduce.
- Confusing species richness with species evenness. Richness is the number of species; evenness is how close in numbers each species population is.
- Describing a high Simpson's index as low diversity. Using D = 1 - sum(n/N)^2, values closer to 1 indicate higher diversity.
- Saying memory cells produce antibodies. Memory B cells divide rapidly on re-infection to form plasma cells, which secrete the antibodies.
Try three Module 4: Biodiversity, Evolution and Disease exam-style questions
1. A sample contains three species with 10, 6 and 4 individuals. Calculate Simpson's index of diversity using D = 1 - sum(n/N)^2. (3 marks)
Show the mark scheme answer
N = 20; sum of (n/N)^2 = 0.25 + 0.09 + 0.04 = 0.38; D = 1 - 0.38 = 0.62.
2. Describe how a neutrophil destroys a bacterium. (4 marks)
Show the mark scheme answer
Neutrophil is attracted by chemicals from the pathogen (chemotaxis); receptors bind to antigens or opsonins on the bacterium; bacterium engulfed by endocytosis into a phagosome; lysosomes fuse with phagosome; lysozymes hydrolyse the bacterium.
3. Explain why the three-domain system replaced the five kingdom system. (3 marks)
Show the mark scheme answer
Molecular evidence such as rRNA sequences showed prokaryotes are two distinct groups; Archaea differ from Bacteria in membrane lipids and RNA polymerase; Archaea share some features with eukaryotes; so prokaryotes are split into Bacteria and Archaea.
Module 4: Biodiversity, Evolution and Disease FAQs
What does OCR A Level Biology A Module 4: Biodiversity, Evolution and Disease cover?
Communicable diseases, disease prevention and the immune system, biodiversity, and classification and evolution.
Which papers is Module 4 examined in?
At A Level it is assessed in Paper 2 (Biological diversity) and Paper 3 (Unified biology); it is also assessed at AS.
Which statistical tests appear in Module 4?
You should be able to use Simpson's index of diversity, and know when to use Spearman's rank correlation and the Student's t-test to analyse variation data.
