7th grade · Science · Unit 3 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.
Maine Learning Results learning standard: MS-LS2-3 · energy flowing through food chains and webs
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 Maine
In the Maine Learning Results, this is unit 3 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.
Source: Maine Department of Education
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
Mushrooms growing on a fallen log are…
- decomposers
- producers
- primary consumers
- herbivores
decomposers
Hint: They break down the dead wood and release nutrients.
Question 2
Put this food chain in order, from the organism that makes food to the last to eat.
- 🐸frog
- 🌾grass
- 🦅hawk
- 🐍snake
grass → frog → snake → hawk
Hint: Energy flows from the producer (grass) to the grasshopper, frog, snake and then hawk.
Question 3
What does an energy pyramid show?
- How tall each organism grows
- How much energy is available at each feeding level
- Where mountains are found
- How many species live in a place
How much energy is available at each feeding level
Hint: The bottom (producers) is widest because it holds the most energy.
Question 4
Grass stores 10,000 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
1000 units
Hint: 10% of the energy is passed on, so divide by 10.
Question 5
Sea otters eat sea urchins, and urchins eat kelp. What can happen if the otters are removed from a coast?
- Kelp grows faster and covers the coast
- The otters become producers
- Urchins disappear
- Urchins increase and the kelp forest can shrink
Urchins increase and the kelp forest can shrink
Hint: Without a predator, urchin numbers rise and they eat more kelp.
Question 6
Producer, consumer or decomposer? Sort each organism.
Sort into: 🌿 producer · 🐇 consumer · 🍄 decomposer
- 🍄a mushroom on a log
- 🌾grass
- 🦅a hawk
- 🟢algae in a pond
- 🍞bread mold
- 🦗a grasshopper
🌿 producer: grass, algae in a pond · 🐇 consumer: a hawk, a grasshopper · 🍄 decomposer: a mushroom on a log, 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).