Question 1: Define a trophic level and describe its role within a food chain.

Answer: A trophic level is a position in a food chain that an organism occupies, based on its source of nutrition. It indicates the organism's role as a producer, consumer, or decomposer, and determines how energy is transferred through the ecosystem.

Question 2: Explain how energy transfer occurs between trophic levels and why it is typically less than 100%.

Answer: Energy transfer between trophic levels occurs when organisms consume others to gain energy. Typically, only about 10% of the energy is transferred to the next level because much is lost as heat, used for metabolic processes, or remains as waste.

Question 1: A primary producer captures 1000 kJ of energy from sunlight. If a herbivore consumes this producer, how much energy (in kJ) is transferred to the herbivore, assuming 10% efficiency in energy transfer?

Answer: 100 kJ

Question 2: If a secondary consumer receives 50 kJ of energy, estimate the energy available at the primary consumer level, assuming 10% transfer efficiency between each trophic level.

Answer: 500 kJ

Question 1: Describe a simple experiment to investigate the effect of fertiliser on plant growth, including variables and safety precautions.

Answer: An experiment could involve growing plants with different fertiliser types or concentrations, measuring plant height over time. The independent variable is fertiliser type/concentration, the dependent is plant growth, and control variables include soil amount and water. Safety precautions include wearing gloves when handling fertilisers and ensuring proper disposal of waste.

Question 1: A farmer observes that after introducing a new predator species to control pests, the populations of herbivores decreased by 40%, and crop yields increased by 25%. Explain how changes in trophic levels can impact food security in this context.

Answer: The introduction of a predator reduces herbivore numbers, decreasing crop damage. This improves food production and security, showing how managing trophic interactions can enhance food availability for humans.

Question 1: Discuss the potential consequences of overhunting top predators on trophic levels and overall food security. Include ecological and economic perspectives in your answer.

Answer: Overhunting top predators can lead to trophic cascades, where prey populations increase unchecked, potentially damaging crops or reducing biodiversity. Ecologically, this disrupts balance; economically, it can threaten fisheries and agriculture. Maintaining predator populations supports ecosystem stability and sustainable food sources.

Question 1: Describe how understanding trophic levels can aid in developing sustainable fishing practices and prevent overfishing.

Answer: Understanding trophic levels helps identify critical species and their roles in ecosystems. Sustainable practices include setting catch limits for top predators and ensuring the balance of food chains, preventing depletion of key populations and maintaining food security.