Biology · Unit 2
The diagrams we drew together — energy flow, food chains, and the big virus question. Open it any time you're reviewing.
Nine is a lot to hold at once. Group them into three buckets of three and they get easy.
what they're made of
staying alive day to day
across a life & generations
The arrows are the whole point: an arrow means “energy passes this way.”
A decomposer doesn't slot between two links. It connects to every level, because it decomposes whatever dies — plants, animals, and waste.
Abstract words like “autotroph” get real when you use actual living things. Each arrow = “is eaten by.”
Each arrow reads “is eaten by” → energy flows the way the arrows point. Scroll sideways for the whole chain →
Most animals eat more than one thing, so chains connect into a web.
Arrows point prey → predator — the direction energy travels.
Only about 10% of energy passes up to the next level — the rest is used for living or lost as heat. So the bottom is always the biggest.
Energy shrinks as you climb — that's why top predators are rare.
The subtle thing most students miss: these two things move differently.
☀️ → 🌱 → 🐄 → 🦁 → 💨
Enters from the sun, gets used up, exits as heat. Gone. It never comes back, so the sun has to keep feeding the system.
🌱 → 🐄 → 💀 → 🍄 → 🌱
The same atoms get reused forever. Decomposers hand the building blocks back to the plants.
Two words, one idea each. (Producer = autotroph. Consumer = heterotroph — write both on the same box so the pair sticks.)
| Autotroph — “self-feeder” | Heterotroph — “other-feeder” |
|---|---|
| Makes its own food | Eats other living things |
| Uses sunlight (photosynthesis) | Gets energy secondhand |
| 🌱 plants, algae | 🐄 🦁 🍄 animals, fungi |
| = PRODUCER | = CONSUMER |
The best way to test the 9 characteristics — a virus passes some and fails others. Try filling in ✓ / ✗ yourself before you read the answers.
A virus is like a USB stick 🧬
It holds genetic instructions and can even evolve — but it does nothing until it's plugged into a living cell. Because it fails the deal-breakers (no cells, no metabolism, can't reproduce alone), most biologists call it non-living. But it's genuinely debated — which is why the assignment asks you to argue a side, not just memorize one.