Describe the roles of decomposers and explain how removing a secondary consumer would impact a food web.

The arrows in the food web indicate the direction of energy flow from one organism to another.

To identify the tertiary consumer, we trace food chains:

• Grass $\rightarrow$ Grasshopper (primary) $\rightarrow$ Blue jay (secondary) $\rightarrow$ Owl (tertiary)
• Grass $\rightarrow$ Rabbit (primary) $\rightarrow$ Snake (secondary) $\rightarrow$ Owl (tertiary)
• Grass $\rightarrow$ Rabbit (primary) $\rightarrow$ Hawk (secondary) $\rightarrow$ Owl (tertiary) The Owl is a tertiary consumer in this food web.

If all the blue jays were removed from the ecosystem:

• The population of grasshoppers would likely increase due to a lack of their predator.
• The owl population, which preys on blue jays, would decrease or be forced to find alternative food sources, potentially impacting other populations like snakes, rabbits, or hawks.

Decomposers (like bacteria and fungi) break down dead organic matter (dead plants, animals, and waste products). This process returns essential nutrients to the soil, making them available for producers and completing the nutrient cycle in the ecosystem.

To calculate the percentage of energy passed from the grasshopper to the blue jay:

The energy at the grasshopper level is $7000 \text{ kJ}$.
The energy at the blue jay level is $600 \text{ kJ}$.

The formula for percentage energy transfer is:

Substitute the given values:

Perform the calculation:

The percentage of energy passed on from the grasshopper to the blue jay is \boxed{\text{8.57%}}.