Food Webs and Energy — Answer Key
Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1. Fix the sentence:
A carnivore is an animal that eats only plants and seeds.
Corrected: A carnivore is an animal that eats only other animals for energy.
The original sentence described a herbivore, not a carnivore. Carnivores like lions and hawks eat only other animals, while herbivores are the ones that eat plants and seeds.
2. Fix the sentence:
Arrows in a food chain point toward the organism that is being eaten.
Corrected: Arrows in a food chain point toward the organism that receives the energy, showing the direction energy flows.
Arrows in a food chain follow the energy, not the eating. They point from the organism being eaten to the one doing the eating, because that is the direction energy travels.
3. Fix the sentence:
An omnivore eats only one type of food, either plants or animals but never both.
Corrected: An omnivore eats both plants and animals, getting energy from many sources.
The prefix "omni" means "all," so an omnivore eats all kinds of food, both plants and animals. Eating only one type would describe a herbivore or carnivore instead.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. A food web shows many overlapping food chains in an ecosystem.
A food web connects many food chains together, showing how different organisms in an ecosystem share food sources and depend on each other.
2. An animal that hunts and eats other animals is called a predator.
A predator is an animal that actively hunts other animals for food. Hawks hunting mice and wolves hunting deer are examples of predators in action.
3. Plants capture energy from the sun to make their own food.
Plants use sunlight as their energy source during photosynthesis. Without the sun, plants could not produce the food that starts every food chain.
4. A primary consumer is an animal that eats producers.
Primary consumers are the first animals in a food chain, so they eat producers like plants and algae. "Primary" means first, which is why they feed directly on producers.
Part C: Short Answer
Answer each question in one or two complete sentences.
1. Why is a food web more realistic than a single food chain?
Sample answer: A food web is more realistic because most animals eat more than one type of food. It shows all the different feeding relationships in an ecosystem, not just one straight path.
In real life, most animals eat several different foods rather than just one. A food web captures all these overlapping connections, while a single food chain only shows one straight path of energy.
2. What role do decomposers play in recycling energy and nutrients?
Sample answer: Decomposers break down dead plants and animals into nutrients that go back into the soil. Producers then use those nutrients to grow, which keeps the cycle going.
Decomposers like fungi and bacteria break down dead organisms and return important nutrients to the soil. Without them, those nutrients would stay locked in dead matter and plants would run out of what they need to grow.