Food Chains and Food Webs
Grade 4 · Science · Study Guide
Learn how energy moves through ecosystems from the sun to plants to animals.
A food chain shows the path of energy from one organism to the next. It always starts with the sun, then a producer (plant), then consumers. Arrows in a food chain point in the direction energy flows. For example: Sun → Grass → Grasshopper → Frog → Snake → Hawk. Each step in the chain is called a trophic level.
But real ecosystems are more complex than a single chain. A food web is made up of many overlapping food chains. Most animals eat more than one thing and get eaten by more than one predator. A food web shows all these connections at once. If one organism in a web disappears, it can affect many others — this is called a cascade effect.
Energy is lost at each level of a food chain. Only about 10% of the energy from one level passes on to the next level. The rest is used for life processes or lost as heat. This is why there are always more plants than herbivores, and more herbivores than carnivores in a healthy ecosystem.
| Level | Role | Example |
|---|---|---|
| 1st | Producer | Grass |
| 2nd | Primary Consumer (Herbivore) | Grasshopper |
| 3rd | Secondary Consumer | Frog |
| 4th | Tertiary Consumer | Hawk |
Key terms
- Food chain
- A sequence showing how energy passes from one organism to the next
- Food web
- A diagram showing all the feeding relationships in an ecosystem
- Trophic level
- Each step in a food chain representing a feeding position
- Predator
- An animal that hunts and eats other animals
- Prey
- An animal that is hunted and eaten by a predator
- Energy flow
- The movement of energy through an ecosystem from producers to consumers
Flashcards
- Food chain
- A sequence showing energy passing from one organism to the next
- Food web
- Many overlapping food chains showing all feeding relationships
- Producer
- First level of every food chain — makes food from sunlight
- Predator
- Animal that hunts other animals for food
- Prey
- Animal that is hunted and eaten by a predator
- 10% rule
- Only 10% of energy passes from one trophic level to the next
Practice questions
What does an arrow in a food chain represent?
- Movement direction
- Energy flow
- Water cycle
- Growth rate
Show answer
Answer: Energy flow
Arrows in a food chain point from the organism being eaten to the organism eating it, showing how energy flows.
Which organism is always at the start of a food chain?
- A carnivore
- A decomposer
- A producer
- A predator
Show answer
Answer: A producer
Food chains always start with a producer (plant) because producers capture energy from the sun through photosynthesis.
A food web is more complex than a food chain.
Show answer
Answer: True
A food web shows many overlapping food chains and is a more realistic picture of feeding relationships in an ecosystem.
All the energy from one trophic level passes to the next.
Show answer
Answer: False
Only about 10% of energy passes from one trophic level to the next. The rest is used for life processes or lost as heat.
An animal that is hunted and eaten by another animal is called ___.
Show answer
Answer: prey
Prey are animals that are hunted by predators. A rabbit is prey for a fox.
Fun facts
- Only about 10% of energy passes from one trophic level to the next — so it takes 10 pounds of plants to make 1 pound of grasshopper!
- A single food web can include hundreds of different species all connected to each other.
- The gray wolf's reintroduction to Yellowstone changed the entire ecosystem — even the rivers moved!
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