Question 1: Define a food web and explain how it differs from a food chain.

Answer: A food web is a complex network of interconnected food chains within an ecosystem, showing how different organisms are related through feeding relationships. Unlike a food chain, which depicts a single linear pathway of energy transfer, a food web illustrates multiple pathways and interactions among various species.

Question 2: Describe the role of primary producers in a food web.

Answer: Primary producers, such as plants and algae, are organisms that produce their own food through photosynthesis, serving as the base of the food web by providing energy for herbivores and other consumers.

Question 1: In an ecosystem, the following data shows the number of individuals in different trophic levels: Primary producers: 500, Herbivores: 100, Carnivores: 20. Explain what this data suggests about energy transfer efficiency in this ecosystem.

Answer: The data indicates that a large number of primary producers support a smaller number of herbivores, and even fewer carnivores. This reflects the typical energy transfer pattern where energy decreases at each trophic level due to energy loss (about 90%) during transfer, resulting in fewer organisms at higher levels.

Question 2: A food web shows that a fox preys on both rabbits and birds. If the rabbit population decreases significantly, what potential effects might this have on the food web?

Answer: A decrease in rabbit population could lead to reduced food availability for the fox, potentially causing a decline in fox numbers. It may also lead to an increase in plants that rabbits feed on, and could impact other predators that compete with foxes.

Question 1: If a primary producer captures 1000 units of energy through photosynthesis, and only 10% of this energy is transferred to herbivores, how much energy is available to herbivores?

Answer: Energy available to herbivores = 1000 units × 0.10 = 100 units

Question 2: Calculate the energy transferred from herbivores to carnivores if the energy received by herbivores is 200 units, and the transfer efficiency is 15%.

Answer: Energy transferred = 200 units × 0.15 = 30 units

Question 1: Design a simple experiment to observe the effect of removing a top predator from a food web. Include the variables involved and safety precautions.

Answer: An experiment could involve setting up two controlled aquatic ecosystems with similar conditions, where in one, a top predator (like a fish) is removed. The independent variable is the presence of the predator, the dependent variables include prey populations and plant growth, and controlled variables include water quality, temperature, and light. Safety precautions include handling equipment carefully, avoiding contamination, and ensuring proper disposal of biological materials.

Question 1: Explain how understanding food webs can help in managing invasive species in an ecosystem.

Answer: Understanding food webs helps identify key species and their roles, enabling managers to predict how invasive species may disrupt existing interactions. This knowledge aids in developing targeted control measures to minimize ecological imbalance.

Question 2: Describe how technology such as DNA analysis can be used to study food webs more effectively.

Answer: DNA analysis allows scientists to identify predator diets accurately by detecting prey DNA in gut contents or feces, providing detailed data on feeding relationships and helping to construct precise food webs.