seegongsik
Grade 5 (age 10-11)

grade 5 Ecosystem

An ecosystem is everything living in one place together with the sunlight, water, soil and air around it, all affecting one another. Producers such as plants make their own food, consumers eat other living things, and decomposers break down dead things and waste. Grass is eaten by a grasshopper, the grasshopper by a frog, the frog by a snake and the snake by a hawk; a line of who-eats-whom like this is called a food chain. In the first picture, raise the level to build the chain link by link. In the second, change the number of frogs and see how the levels just above and below respond.

Food chains: who eats whom

Hawk
🌿 Roles in the food chain
①Producer (grass): uses sunlight to make its own food by photosynthesis.
②Primary consumer (grasshopper): a plant-eating animal.
③Secondary consumer (frog): eats primary consumers.
④Tertiary consumer (snake): eats secondary consumers.
⑤Top consumer (hawk): sits at the end of the chain, so nothing in this chain eats it.

Ecological pyramids: why numbers shrink toward the top

100%
🔺 Why a pyramid shape?
①Only part of the food an animal eats becomes its own body; the rest is used up in breathing and moving.
②So each level up has less food to support it, and fewer living things can survive there.
③For example: 100 grass plants → 20 grasshoppers → 8 frogs → 3 snakes → 1 hawk.
④If a lower level collapses, the levels above it struggle to survive.

When one living thing increases or decreases

What makes up an ecosystem
Ecosystem = living parts (producers, consumers, decomposers) + non-living parts (sunlight, water, soil, air, temperature)
Living things are shaped by the non-living parts, and they change the soil and air in return.
💡 When the number of one living thing changes
①If frogs suddenly decrease, the grasshoppers they used to eat increase.
②With more grasshoppers, the grass they eat decreases.
③Snakes, which eat frogs, run short of food and decrease.
④In real ecosystems, food chains are tangled into webs, so the balance often returns over time; but when a forest is cleared or a river is polluted, recovery is hard.

Summary

Food chain summary
Producer → Primary consumer → Secondary consumer → Tertiary consumer → Top consumer
Many food chains tangled together like a net make a food web.
🎯 Key points
①Food chain: who-eats-whom links joined in a single line.
②Producers: living things such as plants that make their own food.
③Consumers: living things such as animals that get food by eating others.
④Decomposers: bacteria and fungi that break down dead things and waste and return them to the soil.
⑤When one living thing changes in number, the others linked to it by food change too.

Examples and Unit Test

Example 1
In the food chain grass → grasshopper → frog → snake → hawk, which one is the producer that makes its own food?
1
Producers make their own food by photosynthesis; consumers get food by eating other living things.
2
In this chain, only the grass, a plant, makes its own food.
▸ Grass
A food chain always starts with a producer. Without producers, consumers would have nothing to eat.
Example 2
In an ecological pyramid, why are there far fewer hawks than grass plants?
1
Only part of the food an animal eats becomes its body; the rest is used up just staying alive.
2
So less food is available at each level up, fewer living things can survive there, and the pyramid narrows toward the top.
▸ Because less food is passed on at each level up.
The producers at the bottom must be the most numerous to support all the levels above.
Unit-test style
Which statement about ecosystems is correct?
①Producers hunt and eat other animals.
②Plants are producers that make their own food by photosynthesis.
③In an ecological pyramid, there are more living things at the top than at the bottom.
④Decomposers eat only living animals.
⑤If one level of a food chain disappears, other living things are not affected.
▸ ② Plants are producers that make their own food by photosynthesis.
1
Plants make their own food by photosynthesis, so they are the producers at the base of the food chain.
2
Producers do not hunt (①), the pyramid is wider at the bottom (③), decomposers break down dead things and waste (④), and losing one level affects the living things linked to it (⑤).
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