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Pine processionary moths lay eggs that develop into larvae and then into caterpillars, as shown in the diagram - OCR Gateway - GCSE Biology - Question 20 - 2022 - Paper 1
Question 20
Pine processionary moths lay eggs that develop into larvae and then into caterpillars, as shown in the diagram. The caterpillars are a major pest, eating and killin... show full transcript
Worked Solution & Example Answer:Pine processionary moths lay eggs that develop into larvae and then into caterpillars, as shown in the diagram - OCR Gateway - GCSE Biology - Question 20 - 2022 - Paper 1
Step 1
Draw a labelled pyramid of biomass for these feeding relationships showing the organisms at each level.
Answer
A pyramid of biomass consists of three levels:
- Pine Trees (producers) at the bottom, which are consumed by the caterpillars.
- Caterpillars (primary consumers) in the middle, which are eaten by the cuckoos.
- Cuckoos (secondary consumers) at the top.
The biomass decreases as energy flows from the producers to the primary and secondary consumers.
Step 2
Explain how natural selection may have resulted in all cuckoos having the sticky membrane.
Answer
Natural selection is a process where organisms better adapted to their environment tend to survive and reproduce more than others. In this case, cuckoos that had the sticky membrane were more successful in capturing caterpillars, as the membrane trapped the irritating hairs. Over time, these cuckoos were more likely to survive and pass on their genes, leading to the prevalence of the sticky membrane in the population.
Step 4
Step 5
Calculate the percentage increase in the death of larvae on the pine trees compared to in the laboratory for the control treatment.
Answer
The percentage change can be calculated as follows:
Percentage change = ( \frac{(Deaths\ in\ the\ pine\ trees - Deaths\ in\ the\ laboratory)}{Deaths\ in\ the\ laboratory} \times 100 )
Using the control treatment data:
( \text{Percentage change} = \frac{(22 - 13)}{13} \times 100 = 69.23 % )
Thus, the percentage increase is approximately 69.23%.
Step 6
Step 7
Evaluate the use of the two plant oils in the control of the larvae.
Answer
The data suggests that both ginger and rosemary oils are effective in reducing the number of larvae deaths in the laboratory. However, in natural conditions, rosemary shows a lower effectiveness than in the lab, highlighting that environmental factors may influence the efficacy of these oils. Conversely, ginger appears to maintain a stronger impact in the field compared to rosemary, suggesting it could be the more reliable option for natural pest control.