Middle School Science Quiz: Model Food Webs

20 questions · exam conditions

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Model Food WebsQuestion 1 of 20

Food webs show interconnected feeding relationships in an ecosystem. In the food web model below, arrows show the direction of energy transfer (from the organism being eaten to the organism that gets the energy). Producers are the plants.

Model (arrows show energy transfer):

Phytoplankton (producer) → Zooplankton
Phytoplankton (producer) → Snail
Zooplankton → Minnow
Snail → Sunfish
Minnow → Sunfish
Minnow → Heron
Sunfish → Heron

Which statement about the food web model is supported by the arrows?

Energy flows from the heron to the sunfish because the heron is larger.

The heron gets energy from more than one type of consumer.

Phytoplankton gets energy by eating zooplankton.

This model is a single food chain, not a food web, because there is only one top predator.

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Middle School Science Quiz

Middle School Science Quiz: Model Food Webs

Practice Model Food Webs in Middle School Science with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on Model Food Webs, giving you a quick way to practice the rules, question types, and explanations that matter most for Middle School Science.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

All questions

Question 1

Model (arrows show energy transfer):

Phytoplankton (producer) → Zooplankton
Phytoplankton (producer) → Snail
Zooplankton → Minnow
Snail → Sunfish
Minnow → Sunfish
Minnow → Heron
Sunfish → Heron

Which statement about the food web model is supported by the arrows?

Energy flows from the heron to the sunfish because the heron is larger.
The heron gets energy from more than one type of consumer. (correct answer)
Phytoplankton gets energy by eating zooplankton.
This model is a single food chain, not a food web, because there is only one top predator.

Explanation: The core skill is evaluating statements supported by the arrows in a food web model. Food webs show multiple feeding relationships, allowing predators to obtain energy from various consumers in the ecosystem. Arrows represent energy flow, directing from the prey to the predator that receives the energy. A checking strategy is to trace arrow directions to confirm energy transfers and verify if a statement matches the model. A common misconception is that energy flows from larger to smaller organisms, but it actually flows from eaten to eater regardless of size. Food webs illustrate ecosystem interconnections through overlapping energy pathways among species. These interconnections emphasize how diverse feeding habits contribute to ecosystem balance and resilience.

Question 2

Food webs show interconnected feeding relationships in an ecosystem. In the food web model below, arrows show the direction of energy transfer (from food to eater). Producers: mangrove leaves and algae. Consumers: snail, crab, small fish, pelican.

Arrows in the model:

mangrove leaves → snail
mangrove leaves → crab
algae → small fish
snail → crab
crab → pelican
small fish → pelican

Which statement about the food web model is supported?

The pelican gets energy from both crabs and small fish. (correct answer)
Because the crab eats the snail, the arrow should point from crab → snail.
Mangrove leaves are consumers because they provide energy to animals.
This model must be a single chain because it includes only four consumers.

Explanation: The core skill is identifying statements supported by a food web model and its arrows. Food webs show multiple feeding relationships in an ecosystem, mapping out how energy moves through interconnected organisms. In these models, arrows represent the direction of energy transfer, pointing from the food to the consumer that eats it. To check support for a statement, ensure the arrow directions and connections align with the claim. A common misconception is that arrows point from eater to food, but they actually show energy flow from food to eater. Food webs demonstrate the broad interconnections in ecosystems, linking producers to various consumers. Overall, they generalize how these connections maintain energy distribution and ecosystem health.

Question 3

Food webs show interconnected feeding relationships in an ecosystem. In the food web model below, arrows show the direction of energy transfer (from food to eater). Producers: kelp and phytoplankton. Consumers: sea urchin, krill, anchovy, sea otter, seal.

Arrows in the model:

kelp → sea urchin
phytoplankton → krill
krill → anchovy
krill → seal
anchovy → seal
sea urchin → sea otter

Which statement is evidence that this model is a food web (interconnected feeding relationships) rather than a single food chain?

Only one producer (kelp) is shown at the start of the model.
The seal has more than one food source (krill and anchovy). (correct answer)
The largest organism must be the top consumer, so the seal is always at the end.
The arrows show which animals are friends and travel together.

Explanation: The core skill is recognizing evidence that a model represents a food web rather than a single food chain. Food webs show multiple feeding relationships in an ecosystem, capturing branching and overlapping paths of energy transfer among organisms. In these models, arrows represent the flow of energy, pointing from the eaten organism to the eater that receives the energy. To confirm it's a food web, look for organisms with multiple incoming arrows or separate branches in the model. A common misconception is that having only one top consumer means it's a chain, but multiple food sources for any organism indicate a web. Food webs depict the complex interconnections in ecosystems, illustrating how energy disperses through various routes. Understanding these interconnections aids in appreciating ecosystem resilience and vulnerability.

Question 4

Food webs show interconnected feeding relationships in an ecosystem. In the food web model below, arrows show the direction of energy transfer (from food to eater). Producers: algae and pond plants. Consumers: zooplankton, mayfly nymph, small fish, frog, heron.

Arrows in the model:

algae → zooplankton
algae → mayfly nymph
pond plants → mayfly nymph
zooplankton → small fish
mayfly nymph → small fish
mayfly nymph → frog
small fish → heron
frog → heron

Which statement about the food web model is supported by the arrows?

Energy moves from the heron to the frog because the heron is larger.
The mayfly nymph gets energy from only one producer, so this is a single food chain.
The small fish gets energy from both zooplankton and mayfly nymphs. (correct answer)
Pond plants are consumers because other organisms point to them with arrows.

Explanation: The core skill is determining which statements are supported by the arrows in a food web model. Food webs show multiple feeding relationships in an ecosystem, depicting how energy transfers through interconnected paths among producers and consumers. In these models, arrows represent the direction of energy flow, pointing from the food source to the organism that eats it and obtains the energy. To verify a statement, trace the arrows to see if they match the described energy transfers or relationships. A common misconception is that arrow direction is based on organism size, but it always shows energy flow from eaten to eater regardless of size. Food webs illustrate the intricate interconnections in ecosystems, showing how multiple pathways support stability. These models emphasize that ecosystems are networks where changes can ripple through various links.

Question 5

Food webs show interconnected feeding relationships in an ecosystem. In the food web model below, arrows show the direction of energy transfer (from food to eater). Producers: corn plants and weeds. Consumers: caterpillar, mouse, chicken, snake, hawk.

Arrows in the model:

corn plants → caterpillar
corn plants → mouse
weeds → mouse
caterpillar → chicken
mouse → snake
mouse → hawk
chicken → hawk
snake → hawk

If the mouse population increases a lot, which prediction about the food web model is most supported by the arrows?

The hawk may have more energy available because one of its food sources increases. (correct answer)
Corn plants will start eating mice because the mice are more common.
The caterpillar must decrease because food webs only allow one path to the hawk.
The arrows should reverse direction when a population changes.

Explanation: The core skill is making predictions about the effects of population increases in a food web. Food webs show multiple feeding relationships in an ecosystem, allowing energy to flow through diverse channels. In these models, arrows represent energy transfer, pointing from food sources to consuming organisms. To predict effects, trace arrows from the increasing population to see which predators might benefit. A common misconception is that population changes reverse arrow directions, but arrows remain fixed on energy flow. Food webs highlight ecosystem interconnections, showing how abundance in one species affects others. They generalize that these connections promote balance but can amplify changes across the system.

Question 6

Arrows in the model:

cactus → kangaroo rat
desert wildflowers → grasshopper
desert wildflowers → kangaroo rat
grasshopper → lizard
grasshopper → kangaroo rat
lizard → snake
kangaroo rat → snake
snake → hawk
lizard → hawk

If the grasshopper population decreases a lot, which prediction about the food web model is most supported by the arrows?

The desert wildflowers will immediately disappear because they need grasshoppers for energy.
The lizard may have less energy available because one of its food sources is reduced. (correct answer)
The hawk will get more energy because fewer arrows will be in the model.
Nothing in the food web can change because food webs are always static.

Explanation: The core skill is predicting the effects of population changes in a food web based on energy flow. Food webs show multiple feeding relationships in an ecosystem, revealing how organisms are linked through shared or alternative food sources. In these models, arrows represent energy flow, directing from the source being consumed to the organism gaining energy. To predict impacts, follow the arrows from the changing population to see which consumers might gain or lose energy access. A common misconception is that producers depend on consumers for energy, but producers make their own energy and are not affected that way. Food webs highlight ecosystem interconnections, showing how one change can propagate through multiple paths. These models generalize that ecosystems are dynamic networks where balance relies on interconnected species.

Question 7

Food webs show interconnected feeding relationships in an ecosystem. In the food web model below, arrows show the direction of energy transfer (from food to eater). Producers: pine tree seeds and grasses. Consumers: squirrel, rabbit, beetle, fox, hawk.

Arrows in the model:

pine tree seeds → squirrel
pine tree seeds → beetle
grasses → rabbit
grasses → beetle
beetle → fox
rabbit → fox
squirrel → hawk
rabbit → hawk

A student says, "This model shows that the fox gets energy from the hawk." Which choice best evaluates the student's claim using the arrows in the food web model?

Supported, because foxes are smaller so they must get energy from hawks.
Not supported, because food webs can only show one pathway at a time.
Not supported, because there is no arrow from hawk to fox; arrows point from food to eater. (correct answer)
Supported, because energy cycles through the web and returns from hawk to fox.

Explanation: The core skill is evaluating claims about energy transfer using a food web model. Food webs show multiple feeding relationships in an ecosystem, connecting organisms through various energy pathways. In these models, arrows represent the flow of energy, always pointing from the eaten to the eater. To evaluate a claim, check if there is an arrow supporting the described transfer direction. A common misconception is that energy can flow backward or cycle to producers, but it moves unidirectionally. Food webs showcase ecosystem interconnections, revealing dependencies and potential ripple effects. They generalize how these links contribute to the overall functioning and resilience of natural environments.

Question 8

Food webs show interconnected feeding relationships in an ecosystem. In the food web model below, arrows show the direction of energy transfer.

Model:

Phytoplankton (producer) → Krill (consumer)
Phytoplankton (producer) → Mussel (consumer)
Krill (consumer) → Salmon (consumer)
Mussel (consumer) → Sea star (consumer)
Salmon (consumer) → Seal (consumer)

Which statement about the food web model is supported?

Because seals are larger, they must provide energy to salmon.
Phytoplankton is a producer that transfers energy to more than one consumer. (correct answer)
All organisms in the model feed randomly, so arrows could point in any direction.
The food web is the same as a single food chain, so each organism can have only one arrow in and one arrow out.

Explanation: To model food webs, we identify producers and trace how they transfer energy to multiple consumers. Food webs show interconnected feeding relationships where producers (like phytoplankton) can support multiple consumer populations. Arrows indicate energy flow from the organism being consumed to the consumer, not based on size or random connections. To evaluate statements, check if producers have multiple outgoing arrows and if the relationships follow ecological principles. A common misconception is thinking organism size determines energy flow direction or that food webs are just single chains. In this model, phytoplankton has arrows pointing to both krill and mussel, confirming it transfers energy to multiple consumers. This demonstrates how food webs reveal the foundational role of producers in supporting diverse ecosystem communities.

Question 9

Food webs show interconnected feeding relationships in an ecosystem. In the food web model below, arrows show the direction of energy transfer.

Model:

Wildflowers (producer) → Butterfly (consumer)
Wildflowers (producer) → Rabbit (consumer)
Butterfly (consumer) → Spider (consumer)
Spider (consumer) → Bird (consumer)
Rabbit (consumer) → Bird (consumer)

Which claim about feeding relationships is incorrect?

The bird can get energy from both the spider and the rabbit.
The wildflowers get energy from the rabbit because the rabbit depends on them. (correct answer)
The spider gets energy from the butterfly.
The butterfly gets energy from wildflowers.

Explanation: To model food webs correctly, we must understand that arrows show one-way energy transfer from prey to predator. Food webs illustrate multiple feeding relationships where energy flows from producers up through various consumer levels. Arrows always point from the organism being eaten to the organism eating it, never in reverse. To identify incorrect claims, check if the stated relationship matches the arrow direction shown. A critical misconception is thinking organisms lower in the web can get energy from those higher up. The claim that "wildflowers get energy from rabbit" is incorrect because the arrow points from wildflowers to rabbit, meaning rabbit eats wildflowers, not the reverse. Food webs help us understand these unidirectional energy flows that structure ecosystems.

Question 10

Food webs show interconnected feeding relationships in an ecosystem. In the food web model, arrows show the direction of energy transfer.

Model:

Desert plant (producer) → Grasshopper (consumer)
Desert plant (producer) → Kangaroo rat (consumer)
Grasshopper (consumer) → Lizard (consumer)
Kangaroo rat (consumer) → Snake (consumer)
Lizard (consumer) → Snake (consumer)
Snake (consumer) → Hawk (consumer)

A drought causes the desert plant population to decrease.

Which prediction about the food web model is supported?

The snake population will definitely increase because it is at the top of the web.
The grasshopper and kangaroo rat may have less energy available because they get energy from the desert plant. (correct answer)
The hawk will start transferring energy to the snake to keep the web balanced.
Nothing in the web will change because food webs are static once drawn.

Explanation: To model food webs and predict changes, we trace how energy flows through connected organisms. Food webs show multiple feeding relationships where changes to one population can affect others through these connections. Arrows indicate energy transfer pathways, so when a food source decreases, organisms that depend on it may receive less energy. To make predictions, identify all organisms connected to the affected population by following the arrows. A common misconception is thinking food webs are static or that energy can flow backward. Since the desert plant provides energy to both grasshopper and kangaroo rat (arrows point from plant to these consumers), a decrease in plants means less energy available to both. Food webs help us understand how environmental changes cascade through interconnected ecosystems.

Question 11

A pond ecosystem food web model is shown. In this model, arrows show the direction of energy transfer (from the organism being eaten to the organism that gets energy). Producers and consumers are labeled, and food webs show interconnected feeding relationships (not just one chain). Which organism gets energy from multiple sources in the food web?

Food web (arrows show energy transfer):

algae (producer) → zooplankton (consumer)
algae (producer) → tadpole (consumer)
aquatic plants (producer) → snail (consumer)
aquatic plants (producer) → tadpole (consumer)
zooplankton (consumer) → small fish (consumer)
snail (consumer) → small fish (consumer)
tadpole (consumer) → small fish (consumer)
small fish (consumer) → heron (consumer)

Algae
Zooplankton
Small fish (correct answer)
Heron

Explanation: The core skill is identifying organisms that obtain energy from multiple sources in a food web model. Food webs show multiple feeding relationships among organisms, illustrating how various species are connected through what they eat. Arrows in food webs represent the direction of energy flow, pointing from the organism being eaten to the organism that consumes it and gains energy. A useful checking strategy is to trace the arrows pointing to each organism and count if there are more than one incoming from different sources, as seen with the small fish receiving energy from zooplankton, snails, and tadpoles. One misconception is that arrows point from predator to prey, but they actually show energy transfer from prey to predator. Food webs reveal the complex interconnections in ecosystems, where no organism exists in isolation. By modeling these relationships, we can better understand ecosystem stability and the flow of energy.

Question 12

A meadow ecosystem food web model is shown. Arrows show energy transfer (from food to eater). Producers and consumers are labeled, and food webs show interconnected feeding relationships.

Food web:

grass (producer) → rabbit (consumer)
grass (producer) → grasshopper (consumer)
wildflowers (producer) → grasshopper (consumer)
wildflowers (producer) → mouse (consumer)
grasshopper (consumer) → frog (consumer)
grasshopper (consumer) → bird (consumer)
mouse (consumer) → snake (consumer)
frog (consumer) → snake (consumer)
rabbit (consumer) → hawk (consumer)
snake (consumer) → hawk (consumer)

Which statement about the food web model is supported?

(Choose ONE.)

The arrows show which organism is eating the other (from eater to food).
The hawk can get energy through more than one feeding relationship. (correct answer)
Grass is a consumer because it provides energy to many organisms.
This model shows only one possible path for energy to move through the meadow.

Explanation: The core skill is evaluating statements about energy transfer and feeding relationships in food web models. Food webs show multiple feeding relationships, depicting how organisms can have various food sources and predators in an ecosystem. Arrows describe how energy flows, directing from the food source to the consumer that eats it. To check a statement's accuracy, compare it to the model by tracing paths, such as confirming the hawk receives energy from both rabbits and snakes. A misconception is that producers like grass are consumers because they feed others, but producers create their own energy. Food webs highlight ecosystem interconnections, showing multiple energy pathways. This interconnectedness ensures ecosystems are resilient but also vulnerable to disruptions.

Question 13

A grassland ecosystem food web model is shown. In this model, arrows show energy transfer (from the organism being eaten to the organism that gets energy). Producers and consumers are labeled, and food webs show interconnected feeding relationships.

Food web:

grasses (producer) → zebra (consumer)
grasses (producer) → grasshopper (consumer)
acacia (producer) → giraffe (consumer)
acacia (producer) → antelope (consumer)
grasshopper (consumer) → lizard (consumer)
grasshopper (consumer) → bird (consumer)
lizard (consumer) → jackal (consumer)
antelope (consumer) → lion (consumer)
zebra (consumer) → lion (consumer)

Which statement about the food web model is supported?

(Choose ONE.)

Because lions are predators, arrows should point from the lion to the zebra.
The lion can get energy from more than one type of consumer. (correct answer)
Acacia is a consumer because it is connected to giraffes and antelope.
Energy moves in only one path: grasses → zebra → lion.

Explanation: The core skill is analyzing supported statements about energy sources in food web models. Food webs show multiple feeding relationships, enabling top consumers like lions to have diverse energy paths. Arrows represent energy flow, from producers and consumers to those that eat them. A checking strategy is to count incoming arrows, confirming the lion gets energy from zebras and antelopes. One misconception is that arrows should point from predators to prey, but they point from prey to predators. Food webs highlight ecosystem interconnections, with multiple pathways for stability. This understanding reveals how biodiversity supports resilient food systems.

Question 14

A desert ecosystem food web model is shown. In this model, arrows show energy transfer (from the organism being eaten to the organism that gets energy). Producers and consumers are labeled, and food webs show interconnected feeding relationships.

Food web:

cactus (producer) → insect (consumer)
cactus (producer) → kangaroo rat (consumer)
desert grass (producer) → insect (consumer)
desert grass (producer) → rabbit (consumer)
insect (consumer) → lizard (consumer)
insect (consumer) → bird (consumer)
lizard (consumer) → snake (consumer)
kangaroo rat (consumer) → snake (consumer)
rabbit (consumer) → hawk (consumer)
snake (consumer) → hawk (consumer)

Prediction scenario: a disease greatly reduces the number of insects.

Which prediction about the food web model is supported?

(Choose ONE.)

Lizard populations may decrease because they have less energy available from insects. (correct answer)
Cactus populations must decrease because energy flows from lizards to insects.
Hawk populations will not change because food webs are static once made.
Birds will start eating snakes at random to replace insects, even if the model shows no connection.

Explanation: The core skill is predicting changes in populations using food web models. Food webs show multiple feeding relationships, allowing us to see how disruptions affect connected organisms. Arrows represent energy flow, from food sources like insects to consumers such as lizards. A checking strategy is to trace dependencies, predicting lizards may decrease if insects decline due to reduced energy. One misconception is that energy flows backward from consumers to producers, but it only moves toward eaters. Food webs reveal ecosystem interconnections, where one change ripples through. This modeling aids in forecasting environmental impacts on species.

Question 15

A forest ecosystem food web model is shown. In this model, arrows show energy transfer (from the organism being eaten to the organism that gets energy). Producers and consumers are labeled, and food webs show interconnected feeding relationships.

Food web:

oak tree (producer) → caterpillar (consumer)
oak tree (producer) → deer (consumer)
berry bush (producer) → rabbit (consumer)
berry bush (producer) → mouse (consumer)
caterpillar (consumer) → robin (consumer)
mouse (consumer) → owl (consumer)
rabbit (consumer) → fox (consumer)
robin (consumer) → owl (consumer)
deer (consumer) → wolf (consumer)

A student makes a claim: "Because the owl is larger than the robin, energy must flow from the owl to the robin." Which claim about feeding relationships is incorrect based on the food web model?

(Choose ONE.)

Energy can move from caterpillars to robins.
Energy can move from robins to owls.
Energy must flow from owls to robins because owls are larger. (correct answer)
Energy can move from berry bushes to mice.

Explanation: The core skill is identifying incorrect claims about energy flow in food web models. Food webs show multiple feeding relationships, allowing energy to transfer through diverse paths among producers and consumers. Arrows represent energy flow, always pointing from the eaten organism to the eater, regardless of size. A checking strategy is to verify claims against the model, such as noting the arrow from robin to owl disproves energy flowing from owl to robin due to size. One misconception is that larger animals transfer energy to smaller ones, but energy flows based on who eats whom. Food webs illustrate ecosystem interconnections, revealing dependency among species. These models help predict how misconceptions can lead to misunderstanding ecosystem dynamics.

Question 16

An island ecosystem food web model is shown. In this model, arrows show energy transfer (from the organism being eaten to the organism that gets energy). Producers and consumers are labeled, and food webs show interconnected feeding relationships.

Food web:

beach grass (producer) → cricket (consumer)
beach grass (producer) → rabbit (consumer)
shrubs (producer) → mouse (consumer)
shrubs (producer) → rabbit (consumer)
cricket (consumer) → lizard (consumer)
mouse (consumer) → snake (consumer)
lizard (consumer) → hawk (consumer)
snake (consumer) → hawk (consumer)

Which organism gets energy from multiple sources in the food web model?

(Choose ONE.)

Rabbit (correct answer)
Snake
Mouse
Beach grass

Explanation: The core skill is identifying organisms with multiple energy sources in food web models. Food webs show multiple feeding relationships, where some consumers like rabbits eat various producers. Arrows represent energy flow, from sources such as beach grass and shrubs to the consumer. A checking strategy is to look for organisms with incoming arrows from different producers or consumers. One misconception is that all consumers have single sources, but many have diverse diets. Food webs illustrate ecosystem interconnections, promoting adaptability. These models show how variety in food sources enhances survival.

Question 17

A lake ecosystem food web model is shown. Arrows show energy transfer (from food to eater). Producers and consumers are labeled, and food webs show interconnected feeding relationships.

Food web:

algae (producer) → zooplankton (consumer)
algae (producer) → mayfly nymph (consumer)
pondweed (producer) → snail (consumer)
zooplankton (consumer) → minnow (consumer)
mayfly nymph (consumer) → minnow (consumer)
snail (consumer) → sunfish (consumer)
minnow (consumer) → sunfish (consumer)
sunfish (consumer) → osprey (consumer)

Which organism is a producer in the food web model?

(Choose ONE.)

Osprey
Sunfish
Minnow
Algae (correct answer)

Explanation: The core skill is classifying organisms as producers or consumers in food web models. Food webs show multiple feeding relationships, starting with producers that support all other levels. Arrows represent energy flow, beginning from producers like algae to various consumers. To check classification, note that producers have no incoming arrows and make their own energy. A misconception is that all plants are consumers if eaten, but producers generate energy via photosynthesis. Food webs illustrate ecosystem interconnections, with producers as the foundation. These connections emphasize the role of energy origins in sustaining life.

Question 18

A tidepool ecosystem food web model is shown. Arrows show the direction of energy transfer (from food to eater). Producers and consumers are labeled, and food webs show interconnected feeding relationships.

Food web:

seaweed (producer) → limpet (consumer)
seaweed (producer) → sea urchin (consumer)
phytoplankton (producer) → mussel (consumer)
limpet (consumer) → crab (consumer)
mussel (consumer) → crab (consumer)
sea urchin (consumer) → sea otter (consumer)
crab (consumer) → sea otter (consumer)

Which evidence from the model best shows that this is a food web (interconnected feeding relationships) rather than a single food chain?

(Choose ONE.)

Seaweed is shown at the beginning of the model.
The sea otter is shown at the end of two arrows, so it must be the biggest organism.
There are producers and consumers in the model.
The crab gets energy from more than one organism. (correct answer)

Explanation: The core skill is distinguishing food webs from food chains by identifying evidence of interconnected relationships. Food webs show multiple feeding relationships, unlike single linear chains, by including branching paths. Arrows represent energy flow, directing from producers or consumers to those that eat them. To check if it's a web, look for organisms like the crab with multiple incoming arrows from limpets and mussels. A misconception is that being at the end of arrows means an organism is the largest, but size is unrelated to position. Food webs demonstrate ecosystem interconnections, with energy branching in various directions. Understanding this helps appreciate the complexity of natural feeding networks.

Question 19

Food webs show interconnected feeding relationships. In the food web model below, arrows show energy transfer from food to consumer. Producers: kelp, phytoplankton. Consumers: sea urchin, zooplankton, small fish, sea otter, seal.

If the sea urchin population decreases a lot, which prediction about the food web model is best supported?

Kelp will likely increase because less energy is being transferred from kelp to sea urchins. (correct answer)
Sea otters will start getting energy directly from kelp because arrows can reverse when food is scarce.
Zooplankton will stop being consumers and become producers.
Nothing in the web can change because food webs are fixed once drawn.

Explanation: The skill being tested is predicting ecosystem changes based on food web relationships. Food webs show multiple interconnected feeding relationships that help predict cascading effects when populations change. Arrows in food web models represent energy flow from the organism being eaten to its consumer. To make predictions, consider what happens when a food source increases or decreases - if sea urchins eat kelp and sea urchins decrease, then less kelp is being consumed. A common misconception is thinking arrows can reverse or that organism roles (producer/consumer) can change, but these are fixed. Food webs help us understand how changes in one population affect the entire ecosystem through interconnected relationships. When sea urchin populations decrease, their food source (kelp) will likely increase due to reduced grazing pressure.

Question 20

Food webs show interconnected feeding relationships. In the food web model below, arrows show energy transfer from the organism eaten to the consumer. Producers: algae, pond plants. Consumers: snail, mayfly larva, small fish, frog, heron.

Which statement about the food web model is supported by the arrows?

Energy is transferred from the heron to the small fish when the heron eats the fish.
The frog gets energy from both the mayfly larva and the small fish. (correct answer)
Pond plants are consumers because they are eaten by snails.
The food web is a single chain because each organism has only one feeding connection.

Explanation: The skill being tested is interpreting arrow directions and feeding relationships in food web models. Food webs show multiple interconnected feeding relationships between organisms in an ecosystem. Arrows in food web models represent energy flow from the organism being eaten to the consumer that eats it. To verify statements about food webs, trace the arrows to see which organisms provide energy (arrows point away) and which receive energy (arrows point into). A common misconception is thinking arrows point to what an organism eats rather than showing energy transfer direction. Food webs reveal the complex interconnections in ecosystems where organisms often have multiple food sources. The correct answer shows the frog receiving energy from multiple sources, as indicated by arrows pointing to it from different organisms.