7th grade · Science · Unit 7 of 10
Food Chains & Energy
Who eats whom, and the energy
What your child practices
Producers, consumers and decomposers, food chains and webs, how energy shrinks as it passes up a chain (about 10% each step), and what happens when part of a chain changes.
Minnesota K-12 Academic Standards benchmark: 7L.3.1.1.3 · the cycling of matter and flow of energy in an ecosystem
How we explain it
Children can open this short lesson before they practice.
- Producers make food from sunlight. Consumers eat other living things. Decomposers break down dead matter.
- Arrows in a food chain point from the food to the eater.
- Only about 10% of the energy at one level passes to the next.
Example: Plants store 1000 units of energy. About how much reaches the rabbits that eat them? About 10% passes on. 10% of 1000 is 100. Answer: 100 units
Food Chains & Energy in Minnesota
In the Minnesota K-12 Academic Standards, this is unit 7 of 10 in 7th grade Science, after Ecosystems and before Cycles & Succession.
Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
Producer, consumer or decomposer? Sort each organism.
Sort into: 🌿 producer · 🐇 consumer · 🍄 decomposer
- 🦅a hawk
- 🌾grass
- 🦗a grasshopper
- 🟢algae in a pond
- 🦠bacteria in a compost pile
- 🍞bread mold
🌿 producer: grass, algae in a pond · 🐇 consumer: a hawk, a grasshopper · 🍄 decomposer: bacteria in a compost pile, bread mold
Hint: Producers make their own food from sunlight (plants, algae). Consumers eat other living things. Decomposers break down dead matter (many fungi and bacteria).
Question 2
In a food chain, which organism has the smallest amount of available energy?
- the top consumer
- the Sun
- the primary consumer
- the producer
the top consumer
Hint: Energy shrinks at every step, so the last level has the least.
Question 3
Grass stores 5000 units of energy. About 10% of the energy at each feeding level is passed on to the next. How many units reach the grasshoppers that eat the grass?
answer boxunits
500 units
Hint: 10% of the energy is passed on, so divide by 10.
Question 4
Put this food chain in order, from the organism that makes food to the last to eat.
- 🐸frog
- 🐍snake
- 🦅hawk
- 🦗grasshopper
grasshopper → frog → snake → hawk
Hint: Energy flows from the producer (grass) to the grasshopper, frog, snake and then hawk.
Question 5
What is a food web?
- Many food chains linked together
- A list of producers
- A spider's web full of insects
- A food chain with only one organism
Many food chains linked together
Hint: Most organisms eat more than one thing and are eaten by more than one thing.
Question 6
What is a consumer?
- A rock that stores heat
- An organism that makes food from sunlight
- An organism that gets energy by eating other organisms
- A non-living resource
An organism that gets energy by eating other organisms
Hint: Consumers cannot make their own food, so they eat producers or other consumers.