6 exam-style questions with full mark schemes and model answers. Write your own answer and the AI examiner marks it against the mark scheme.
Learn this properly: Evidence for EvolutionA population of bacteria causes an infection in a hospital. At first, an antibiotic kills almost all of the bacteria. After the antibiotic has been used for several years, a strain of bacteria appears that the antibiotic can no longer kill — it is antibiotic-resistant.
Explain how a population of antibiotic-resistant bacteria can develop by natural selection. (6 marks)
Human insulin is now produced by genetically engineered bacteria. The diagram description below outlines the main stages of genetic engineering.
(a) Name the type of enzyme used to cut the human insulin gene out of the DNA. (1 mark)
(b) Name the enzyme used to join the insulin gene into the bacterial plasmid. (1 mark)
(c) Explain why a plasmid is described as a vector in this process. (2 marks)
For thousands of years, farmers have used selective breeding to increase the milk yield of dairy cattle.
(a) Describe how a farmer could use selective breeding over many generations to produce a herd of cattle with a high milk yield. (2 marks)
(b) Selective breeding can reduce the gene pool of a population. State one problem this can cause. (1 mark)
The peppered moth exists as a pale form and a dark (melanic) form. A scientist released equal numbers of both forms in a heavily polluted woodland where the tree bark was darkened by soot, then recorded how many of each form were recaptured.
| Moth form | Number released | Number recaptured |
|---|---|---|
| Pale | 100 | 16 |
| Dark | 100 | 40 |
(a) Calculate the percentage of the pale moths that were recaptured. (1 mark)
(b) Using natural selection, explain why a higher percentage of dark moths than pale moths was recaptured in this polluted woodland. (2 marks)
Some crops are genetically modified (GM) to make them resistant to insect pests.
Give one benefit and one risk of growing GM insect-resistant crops. (2 marks)
Charles Darwin and Alfred Russel Wallace independently developed the theory of evolution by natural selection.
Name the famous book, published by Darwin in 1859, that set out the theory of evolution by natural selection in full. (1 mark)