Question 1: Define a trophic level and explain its role within an ecosystem.

Answer: A trophic level is a position an organism occupies in a food chain, representing its source of energy, such as producers, consumers, or decomposers.

Question 2: Describe how overfishing can affect the trophic levels within a marine ecosystem.

Answer: Overfishing can reduce the population of top predators, leading to an imbalance that may cause an increase in lower trophic levels and disrupt ecosystem stability.

Question 3: Calculate the biomass loss if 1000 kg of a fish population at trophic level 3 is reduced by 20%.

Answer: Biomass loss = 1000 kg × 20% = 200 kg

Question 4: Using the concept of energy transfer efficiency (typically 10%), estimate the amount of energy transferred from trophic level 2 to trophic level 3 if the energy at level 2 is 10,000 kJ.

Answer: Energy transferred = 10,000 kJ × 10% = 1,000 kJ

Question 5: Identify one sustainable fishing practice and explain how it helps maintain trophic level balance.

Answer: Selective fishing methods, such as size limits and catch quotas, help prevent overfishing of key species, maintaining balance across trophic levels.

Question 6: Explain the potential ecological consequences if top predators are removed from a marine food chain due to unsustainable fishing.

Answer: Removing top predators can lead to a trophic cascade, resulting in an overpopulation of prey species, depletion of lower-level producers, and overall ecosystem imbalance, potentially causing habitat degradation and loss of biodiversity.

Question 7: Fill in the blank: The practice of setting catch limits based on scientific data is called ________.

Answer: quota management

Question 8: Multiple Choice: Which of the following is a benefit of sustainable fishing practices? A) Depletion of fish stocks B) Maintaining ecosystem stability C) Increasing overfishing D) Reducing biodiversity

Answer: B) Maintaining ecosystem stability

Question 9: Describe one experiment you could design to test the effectiveness of a sustainable fishing quota system.

Answer: An experiment could involve comparing fish populations in two similar marine areas—one with implemented catch quotas and one without. Variables include fishing effort and species diversity; data collected over time would assess population changes and ecosystem health.

Question 10: Analyse the impact of reducing fishing effort on trophic level stability in a marine ecosystem.

Answer: Reducing fishing effort can allow overfished species to recover, restoring predator-prey relationships and stabilising trophic levels. It decreases the risk of trophic cascades, promotes biodiversity, and supports sustainable ecosystem functioning.

Question 11: Explain how modern technology, such as satellite tracking and data collection, can improve sustainable fishing practices.

Answer: Modern technology allows precise monitoring of fishing activities, helps enforce catch limits, tracks fish migrations, and collects data to inform sustainable management, reducing overfishing and environmental damage.