Question

predict
before you begin the investigation, make a prediction.
in a marine food web, algae produce their food using energy fr
sun, and barracuda get their energy from eating other fish.

• which organism would appear high on the food web? which

appear low on the food web?

• if algae absorb 100 units of energy from the sun, how much

that energy do you think will transfer to the barracuda? exp
your thinking.
initial prediction record a prediction of how many energy units w
transfer from the algae to the barracuda in the marine food web. e
your reasoning.

Explanation:

For the first sub - question (organism high/low on food web)

In a marine food web, producers (like algae) are at the lowest trophic level as they convert solar energy into food. Consumers that are top predators (like barracuda, which eat other fish) are at higher trophic levels. So barracuda would be high on the food web and algae would be low.

Step1: Recall energy transfer rule

In a food web, typically only about 10% of the energy from one trophic level is transferred to the next trophic level. But since barracuda is not a direct consumer of algae (algae is likely eaten by smaller fish, which are then eaten by barracuda), we have multiple trophic levels between them. Let's assume there are two trophic levels between algae and barracuda (algae→small fish→larger fish→barracuda is a bit too long, but for simplicity, if we consider two transfers: algae to primary consumer (10% of 100 = 10), then primary consumer to secondary consumer (10% of 10 = 1), and secondary consumer to barracuda (10% of 1 = 0.1). But if barracuda is two trophic levels above algae (algae→fish→barracuda), then first transfer: 10% of 100 = 10, second transfer: 10% of 10 = 1. So the energy transferred to barracuda would be much less than 100, likely around 1 unit or less (depending on the number of trophic levels).

Step2: Calculate based on 10% rule (simplified)

If we consider the energy transfer efficiency of 10% per trophic level and assume barracuda is two trophic levels above algae (algae is level 1, primary consumer level 2, barracuda level 3).
Energy at level 2 (from algae): $100\times0.1 = 10$ units.
Energy at level 3 (barracuda): $10\times0.1=1$ unit.

Answer:

• Organism high on the food web: Barracuda (because it is a top - level consumer that eats other fish).
• Organism low on the food web: Algae (because it is a producer that makes food using solar energy).

For the second sub - question (energy transfer)