Food Webs and Energy Flow in Ecosystems Worksheet

Question 1

In a grassland ecosystem, grass is eaten by a rabbit, and the rabbit is eaten by a hawk. Identify the producer, the primary consumer, and the secondary consumer.

Accepted Answer

The grass is the producer because it makes its own food. The rabbit is the primary consumer because it eats the producer. The hawk is the secondary consumer because it eats the primary consumer.

Question 2

Explain why the Sun is the original source of energy for most food webs.

Accepted Answer

The Sun is the original source of energy for most food webs because producers, such as plants and algae, use sunlight to make food through photosynthesis. That stored energy is then passed to consumers when they eat producers or other consumers.

Question 3

A pond food chain is algae -> insect larva -> fish -> heron. Describe how energy flows through this food chain.

Accepted Answer

Energy flows from the Sun to the algae, which make food. The insect larva gets energy by eating the algae, the fish gets energy by eating the insect larva, and the heron gets energy by eating the fish.

Question 4

What is the main difference between a food chain and a food web?

Accepted Answer

A food chain shows one simple path of energy flow from one organism to another. A food web shows many connected food chains and the multiple feeding relationships in an ecosystem.

Question 5

A fox eats rabbits, mice, and berries. What does this tell you about the fox's role in the food web?

Accepted Answer

This tells us that the fox is an omnivore because it eats both animals and plant material. In the food web, it can act as a consumer at more than one feeding level depending on what it eats.

Question 6

Decomposers such as fungi and bacteria break down dead organisms. Explain why decomposers are important in an ecosystem.

Accepted Answer

Decomposers are important because they break down dead plants, animals, and wastes. This returns nutrients to the soil or water, where producers can use them again, helping matter cycle through the ecosystem.

Question 7

If a large number of insects in a forest die from disease, how might this affect frogs and hawks in the same food web?

Accepted Answer

Frogs may have less food available if they eat insects, so their population could decrease. Hawks could also be affected if they depend on frogs or other insect-eating animals for food, because less energy would move up the food web.

Question 8

In an ocean ecosystem, phytoplankton are eaten by zooplankton, which are eaten by small fish. Which organism is the primary consumer, and why?

Accepted Answer

The zooplankton are the primary consumer because they eat the producer, which is the phytoplankton. Primary consumers get energy directly from producers.

Question 9

Why is less energy available at the top of a food pyramid than at the bottom?

Accepted Answer

Less energy is available at the top of a food pyramid because organisms use much of the energy they take in for life processes such as movement, growth, and staying alive. Only part of the energy is passed on to the next trophic level.

Question 10

A student says that energy cycles through an ecosystem in the same way that matter does. Is the student correct? Explain your answer.

Accepted Answer

The student is not correct. Matter cycles through ecosystems because nutrients are reused, but energy flows in one direction through the ecosystem and is eventually lost as heat, so it does not cycle in the same way.

Question 11

List one example of a producer, one herbivore, one carnivore, and one decomposer in a forest ecosystem.

Accepted Answer

One possible example is an oak tree as the producer, a deer as the herbivore, a wolf as the carnivore, and a mushroom as the decomposer. Other correct forest examples are also acceptable.

Question 12

How would removing all producers from an ecosystem affect the rest of the food web?

Accepted Answer

Removing all producers would cause the food web to collapse because producers are the main entry point for energy into the ecosystem. Herbivores would lose their food source first, and then higher-level consumers would also lose their sources of energy.

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Food Webs and Energy Flow in Ecosystems

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