Energy in Ecosystems — Answer Key
Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1. Fix the sentence:
A herbivore is an animal that eats only meat.
Corrected: A herbivore is an animal that eats only plants.
Herbivores like deer and rabbits get all of their energy by eating producers.
2. Fix the sentence:
An omnivore is an animal that eats only insects.
Corrected: An omnivore is an animal that eats both plants and animals.
Omnivores get energy from many sources, eating both producers and other consumers.
3. Fix the sentence:
A top predator is the first consumer in a food chain.
Corrected: A top predator is the last consumer in a food chain.
Top predators sit at the highest level of the food chain and have few or no natural enemies.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. An animal that eats only plants is called a herbivore.
Herbivores are primary consumers because they eat producers directly.
2. An animal that eats only other animals is called a carnivore.
Carnivores eat other consumers and are usually secondary or tertiary consumers.
3. An animal that eats both plants and animals is an omnivore.
Omnivores have flexible diets, which helps them survive in changing ecosystems.
4. An animal that hunts and eats other animals is called a predator.
Predators control prey populations and help keep ecosystems balanced.
Part C: Short Answer
Answer each question in one or two complete sentences.
1. What is the difference between a primary consumer and a secondary consumer?
Sample answer: A primary consumer eats producers like plants, so it is usually a herbivore. A secondary consumer eats primary consumers, so it is usually a carnivore or omnivore that hunts other animals.
Grade 5 students learn that consumer levels are named by what they eat in the food chain.
2. Why do top predators usually have small populations in an ecosystem?
Sample answer: Top predators have small populations because energy decreases at each level of the food chain. There is less energy available at the top, so fewer top predators can be supported by the ecosystem.
About 90 percent of energy is lost as heat at each level, leaving little for top predators.