Evolution, speciation and scientific validationEdexcel A-Level Biology A: Flashcards

Exam questions on Evolution, speciation and scientific validation

1. A hospital ward is treated repeatedly with an antibiotic to control a population of Staphylococcus bacteria. Before the treatment began, about 1 in 10 000 of the bacteria carried an allele that made them resistant to the antibiotic. After two weeks of repeated treatment, most of the bacteria on the ward carried the resistance allele.
   Explain why the frequency of the resistance allele increased on the ward.2 marks
2. A research team compares the amino acid sequence of the beta chain of haemoglobin in four species of primate. Species A and B differ by 1 amino acid, species A and C differ by 6 amino acids and species A and D differ by 14 amino acids. The team concludes that the data support the theory that the four species evolved from a common ancestor. They submit their findings to a scientific journal and also present them at an international conference.
   Explain how presenting their findings at an international conference could help to validate the team's conclusion.2 marks
3. In a woodland near an industrial city, the proportion of dark (melanic) peppered moths rose from 5% in 1850 to 95% in 1900. Soot had darkened the tree trunks on which the moths rest during the day, and birds found light moths easier to see. After clean air laws were introduced, the proportion of dark moths in the woodland fell from 95% in 1960 to 11% in 1990.
   Explain how the proportion of dark moths increased between 1850 and 1900.3 marks