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Edexcel A-Level Biology A2 5.23 Evolution By Mutation and Natural Selection Questions

Explain how heritable variation and selection pressures change allele frequencies, producing adaptations and resistance across generations.

Syllabus
First assessment 2019
Course
Biology YBI11
Level
A2

Exam points

  • explain how mutation creates heritable variation and new alleles in a population
  • explain how selection pressures change survival, reproduction and allele frequencies across generations
  • apply evolution principles to adaptations, resistance and artificial-selection outcomes in real populations

Edexcel A-Level Biology A2 5.23 Evolution By Mutation and Natural Selection Questions question 1

[Maximum number: 3]

Aquaculture is the controlled cultivation of aquatic organisms such as fish, shellfish and plants. It is an important source of food in many countries of the world. The photograph shows freshwater aquaculture ponds in Africa.

Figure for Question Edexcel A-Level Biology A2 5.23 Evolution By Mutation and Natural Selection Questions question 1 — Edexcel A-Level Biology A2

Vibrio are bacteria that are common in aquatic habitats. They cause diarrhoea and cholera and are also pathogenic to shellfish. The resistance of Vibrio to antibiotics and to heavy metals in aquaculture ponds in Nigeria was investigated.

The samples of Vibrio taken from each pond were spread on agar containing different antibiotics.

The scientists expected the percentage of resistant bacteria to be higher in the samples of Vibrio taken from the ponds previously treated with antibiotics. Explain why the scientists expected this difference.

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