Ecosystems, Matter & Energy — Extension · Life Science & Scientific Inquiry, Grade 7
Five focused units, a three-session investigation, chapter review, and chapter quiz.
Account for ecosystem energy and matter
Investigate
How do a food pathway and a water budget answer different questions?
Materials
- Supplied energy and water records
- Notebook for two separate labeled models
Before you begin
Analyze the supplied records; no organism collection, chemical mixing, or heating is required.
Plan a fair test
Keep energy levels in the same boundary and interval. Track the separate water budget in liters rather than mixing its quantities with energy.
Method
- Draw resource-to-consumer arrows using a stated convention.
- Calculate each energy-transfer percentage from the supplied levels.
- Explain energy destinations outside the next feeding position.
- Calculate the separate water storage change.
- Compare matter cycling and energy flow, then identify a missing pathway that would alter a budget.
Illustrative course data — use for analysis without equipment
Illustrative records: these are invented teaching data, not published measurements or the learner’s own observations. Actual measurements may differ; record them separately if you perform an optional suitable activity.
| Record | Values |
|---|---|
| Energy per interval | Producers 2000 units; first consumers 300; second consumers 60 |
| Pond inputs | Rain 40 L; runoff 20 L |
| Pond outputs | Evaporation 25 L; outflow 15 L |
Analyze and explain
- Are both energy transfers ten percent?
- What is the water storage change?
- Why should successive energy levels not be added as separate new inputs?
What a strong explanation includes
- Explain the relevant biological process accurately.
- Use the supplied evidence and show calculation steps with units where needed.
- Connect a labeled model or mechanism with the claim.
- State an assumption, evidence limitation, or useful next observation.
Parent / teacher guide: discuss after the investigation
Energy transfers are 300/2000=15% and 60/300=20%. The later energy is part of earlier pathways, so adding all levels as independent energy inputs would double-count. Water inputs total 60 L and outputs 40 L, giving +20 L storage. Matter can move among reservoirs while energy flows and much spreads as heat. Both models require complete stated boundaries and pathways.
Compare this model with the learner’s actual evidence. Different measurements can support a different conclusion; check the reasoning and limitations, not matching wording.
Extend the chapter investigation by evaluating its evidence and proposing a better test.
Problem 1
Answer and explanation
Energy transfers are 300/2000=15% and 60/300=20%. The later energy is part of earlier pathways, so adding all levels as independent energy inputs would double-count. Water inputs total 60 L and outputs 40 L, giving +20 L storage. Matter can move among reservoirs while energy flows and much spreads as heat. Both models require complete stated boundaries and pathways.
Problem 2
Answer and explanation
Energy transfers are 300/2000=15% and 60/300=20%. The later energy is part of earlier pathways, so adding all levels as independent energy inputs would double-count. Water inputs total 60 L and outputs 40 L, giving +20 L storage. Matter can move among reservoirs while energy flows and much spreads as heat. Both models require complete stated boundaries and pathways.
Problem 3
Answer and explanation
Energy transfers are 300/2000=15% and 60/300=20%. The later energy is part of earlier pathways, so adding all levels as independent energy inputs would double-count. Water inputs total 60 L and outputs 40 L, giving +20 L storage. Matter can move among reservoirs while energy flows and much spreads as heat. Both models require complete stated boundaries and pathways.