A mushroom grower tests parasitic wasps as a biological control for fungus gnat larvae. The grower introduces the wasps into three growing rooms. Three other growing rooms have no wasps. All six rooms otherwise have the same conditions.
| Growing room | Treatment | Larvae at start | Larvae after 12 days |
|---|---|---|---|
| W1 | parasitic wasps | 240 | 62 |
| W2 | parasitic wasps | 225 | 67 |
| W3 | parasitic wasps | 255 | 81 |
| N1 | no parasitic wasps | 235 | 166 |
| N2 | no parasitic wasps | 245 | 174 |
| N3 | no parasitic wasps | 240 | 170 |
Calculate the percentage decrease in the total number of larvae in the three growing rooms containing parasitic wasps.
Evaluate the conclusion that the parasitic wasps caused all of the decrease in the number of larvae. Use the data in the table and your answer to (a).
100 exam-style questions on Edexcel GCSE Biology 4.3 Selective breeding and genetic modification, covering 4.3.1 Selective breeding and its impact, 4.3.2 Tissue culture, 4.3.3 Genetic engineering overview, 4.3.4 Main stages of genetic engineering, 4.3.5 Advantages and disadvantages of GM organisms, 4.3.6 Agricultural solutions for a growing population, and 4.3.7 Evaluating genetic engineering and breeding. Each one has a worked solution and a mark scheme showing where the marks go.