OCR GCSE Biology B (Twenty First Century)
OCR GCSE Biology B B6.1 How was the theory of evolution developed? Exam Questions
Free OCR GCSE Biology B exam questions for B6.1 How was the theory of evolution developed?, with a mark scheme for every pack. Covers natural selection, variation, Darwin and Wallace, evidence for evolution, fossils, antibiotic resistance, speciation and how scientific theories gain acceptance.
B6.1 How was the theory of evolution developed? exam questions
2 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 GCSE Biology B B6.1 How was the theory of evolution developed?
B6.1 opens chapter B6, Life on Earth, Past, Present and Future, with the theory of evolution by natural selection. You need to explain how variation, competition, survival and reproduction lead to changes in allele frequency over many generations, and describe the evidence, including fossils and antibiotic resistance in bacteria. The historical development of the theory, including the work of Darwin and Wallace, the reasons it was slow to be accepted, and how it differs from Lamarck's ideas, highlights how science works. This draws on genetics from B1 and leads to classification in B6.3. Examiners often ask for step-by-step natural selection explanations.
What you need to know
- Evolution Evolution is the change in the inherited characteristics of a population over time through natural selection, which may result in new species.
- Natural selection There is genetic variation in a population; individuals with variants better suited to the environment are more likely to survive and reproduce; they pass on their alleles, so these become more common over many generations.
- Darwin and Wallace Darwin developed the theory from observations on the voyage of HMS Beagle, including Galapagos finches, and published On the Origin of Species in 1859. Wallace independently reached similar conclusions.
- Acceptance of the theory It was controversial because it challenged religious beliefs, there was not enough evidence at the time, and the mechanism of inheritance was unknown until genetics developed.
- Evidence Fossils show how organisms have changed over time. Antibiotic-resistant bacteria evolve rapidly, showing natural selection in action.
- Speciation Populations that become isolated, for example geographically, evolve separately until they can no longer interbreed to produce fertile offspring, forming new species.
- Lamarck Lamarck proposed that characteristics acquired during a lifetime are passed on. This was rejected because acquired changes do not alter the genes passed to offspring.
Common mistakes in B6.1 How was the theory of evolution developed?
- Saying organisms adapt or change because they need to. Variants already exist and selection acts on them.
- Writing that individuals evolve. Populations evolve over generations; individuals do not.
- Using survival of the fittest without explaining reproduction. Stress that survivors reproduce and pass on their alleles.
- Saying bacteria become resistant by being exposed to antibiotics. A random mutation gives resistance and those bacteria survive and multiply.
- Confusing Darwin's theory with Lamarck's. Lamarck's idea was inheritance of acquired characteristics.
Try three B6.1 How was the theory of evolution developed? exam-style questions
1. Name the scientist who developed the theory of natural selection independently of Darwin. (1 mark)
Show the mark scheme answer
Alfred Russel Wallace.
2. A population of 2000 bacteria contains 50 resistant to an antibiotic. Calculate the percentage resistant. (2 marks)
Show the mark scheme answer
50 / 2000 x 100; = 2.5%.
3. Explain how a population of bacteria becomes resistant to an antibiotic. (4 marks)
Show the mark scheme answer
A random mutation gives some bacteria resistance; when the antibiotic is used, non-resistant bacteria are killed; resistant bacteria survive and reproduce with less competition; the resistance allele is passed on and becomes more common in the population.
B6.1 How was the theory of evolution developed? FAQs
What does OCR GCSE Biology B B6.1 cover?
It covers evolution by natural selection, the work of Darwin and Wallace, evidence from fossils and antibiotic resistance, speciation and why the theory took time to be accepted.
Which paper is B6.1 examined in?
J257 has two papers at each tier, Breadth in Biology and Depth in Biology, and content from any chapter, including B6, can be assessed on either one. Expect it to be linked to ideas about science and to other chapters.
How do I write a full natural selection answer?
Include variation from mutations, a selection pressure, better adapted individuals surviving and reproducing, alleles being passed on, and the allele becoming more common over many generations.
