Final answer:
Approximately 5 hawks can be supported by the food chain in question, considering the 10% energy transfer rule and the given biomass of each organism in the chain.
Step-by-step explanation:
To calculate the number of hawks that could be supported by the food chain consisting of leaves > caterpillar - robin > hawk, we must consider the biomass at each trophic level and the standard 10% energy transfer rule. Given the biomass of leaves (producers) is 5,000,000 grams, only about 10% of that energy is passed on to the next trophic level (caterpillars). Therefore, caterpillars would receive 500,000 grams of biomass. As each caterpillar has a mass of 0.5 grams, this translates to 1,000,000 caterpillars.
The next level up would be robins, which would receive 10% of the caterpillar's biomass, equivalent to 50,000 grams of biomass (500,000 grams × 10%). With each robin having a mass of 75 grams, this means about 666 robins could be supported (50,000 grams / 75 grams per robin).
Finally, hawks at the top level would receive 10% of the robin's biomass, which is 5,000 grams (50,000 grams × 10%). With each hawk having a mass of 1,000 grams, approximately 5 hawks could be supported (5,000 grams / 1,000 grams per hawk).