In Florida, mangrove trees grow as part of an intertidal ecosystem. A simplified model of a food web in a Florida mangrove forest is shown.

The figure presents a food web. The following organisms are represented: Mangrove leaves, Phytoplankton, Prawn, Snail, Small Fish, Pelican, and Heron. Mangrove leaves are shown in the bottom left side of the figure. Arrows are drawn from Mangrove leaves to Prawn and Snail. Phytoplankton are shown in the bottom right side of the figure, and an arrow is drawn from Phytoplankton to Prawn. Arrows are drawn from Snail and Prawn to Small Fish. An arrow is also drawn from Prawn to Heron. An arrow is drawn from Small fish to Pelican, and an arrow is drawn from Small Fish to Heron.
Question
Which of the following claims about population size in the community is best supported using evidence from the food web?

Phytoplankton have the largest population size because light is an unlimited resource, so there is little competition with mangroves for light.

Answer A: Phytoplankton have the largest population size because light is an unlimited resource, so there is little competition with mangroves for light.
A

Mangroves have the largest population size because trees are closer to the source of light than are phytoplankton.

Answer B: Mangroves have the largest population size because trees are closer to the source of light than are phytoplankton.
B

Prawns have the largest population size because there is no competition for phytoplankton in the community.

Answer C: Prawns have the largest population size because there is no competition for phytoplankton in the community.
C

Herons and pelicans have the largest population size because they are top predators in the community.

To determine which student model best predicts the energy distribution in the food chain, let's analyze the given information in the question.

In the food web shown, the arrows represent the flow of energy in the ecosystem. The arrows point from the organisms being consumed to the organisms that consume them.

In the food web, mangrove leaves and phytoplankton (bottom-level organisms) provide energy to the next trophic level, which includes prawns and snails. Arrows are drawn from mangrove leaves to prawns and snails, indicating that they feed on the leaves. Additionally, there is an arrow from phytoplankton to prawns, meaning that prawns also feed on phytoplankton.

Small fish feed on prawns and snails, as represented by the arrows from prawns and snails to small fish.

There is an arrow from prawns to herons, indicating that herons consume prawns.

Lastly, there are arrows from small fish to both pelicans and herons, indicating that both these birds consume small fish.

Now, let's analyze the two student models:

Student Model 1:
- Pelicans are represented at the bottom level of the pyramid, followed by small fish, prawns, and phytoplankton at the top.
- The arrow next to the pyramid indicates that there is "More Energy" at the bottom and "Less Energy" at the top.

Student Model 2:
- Phytoplankton are represented at the bottom level of the pyramid, followed by prawns, small fish, and pelicans at the top.
- The arrow next to the pyramid indicates that there is "More Energy" at the bottom and "Less Energy" at the top.

Based on the information provided, we can conclude that the correct answer is:

Answer A: Student model 1 is more accurate than student model 2 because there is less energy stored in populations at higher trophic levels.

Justification:
In a food chain, energy flows from lower trophic levels to higher trophic levels. As we move up the food chain, there is a decrease in energy stored at each trophic level. Student Model 1 accurately represents this concept, placing organisms with higher energy storage (phytoplankton and prawns) at the lower levels, and organisms with lower energy storage (pelicans) at the top level. Student Model 2, on the other hand, incorrectly suggests that there is more energy stored at higher trophic levels, which goes against the natural flow of energy in a food chain.

To determine which claim about population size in the community is best supported using evidence from the food web, we need to carefully analyze the relationships between the organisms and their roles in the ecosystem.

Looking at the food web, we can see that the primary producers in this ecosystem are the mangrove leaves and the phytoplankton. These organisms are the basis of the food chain as they convert energy from the sun into organic matter through photosynthesis.

The arrows in the food web indicate the flow of energy and nutrients. Mangrove leaves and phytoplankton are connected to the prawn and snail, implying that these organisms consume the leaves and phytoplankton. Next, the small fish is connected to the prawn and snail, indicating that it feeds on them. Finally, the heron and pelican are connected to the small fish, indicating that they consume the small fish.

Based on this information, let's evaluate each claim:

Claim A: Phytoplankton have the largest population size because light is an unlimited resource, so there is little competition with mangroves for light.
This claim is not supported by the food web. While phytoplankton play an important role in the ecosystem as primary producers, there is competition for them from the prawn and snail, which feed on them.

Claim B: Mangroves have the largest population size because trees are closer to the source of light than are phytoplankton.
This claim is also not supported by the food web. Although mangroves are primary producers and play a vital role in the ecosystem, they are not directly connected to any organism in the food web, implying that they are not a significant food source for other organisms in this particular ecosystem.

Claim C: Prawns have the largest population size because there is no competition for phytoplankton in the community.
This claim is partially supported by the food web. The arrows indicate that prawns feed on both phytoplankton and the snail. While they do face competition for phytoplankton from other organisms, they do not face direct competition in the food web from other organisms for the snail.

Claim D: Herons and pelicans have the largest population size because they are top predators in the community.
This claim is not supported by the food web. While herons and pelicans hold a predatory role in the ecosystem, they are not directly connected to the primary producers or other organisms in the food web. They depend on the availability of small fish as their prey.

Considering the evidence from the food web, the claim that is best supported is Answer C: Prawns have the largest population size because there is no competition for phytoplankton in the community. Although prawns face some competition for phytoplankton, they do not face direct competition in the food web for the snail, which provides an additional food source for them.