How can organisms obtain energy when oxygen is unavailable?
Submit: An evidence record, explanation and revision.
Related lesson: Ecology and Sustainability
This is a teacher-led extension beyond the short lesson. The task supplies a performance opportunity; completion alone does not certify mastery, full NGSS coverage or state alignment.
Teacher review guideBuild the idea
Organisms can release energy from organic matter through aerobic respiration or pathways that do not use oxygen. Fermentation regenerates carriers needed for continued glycolysis and releases much less usable energy per glucose than aerobic respiration. Matter still has to be accounted for; anaerobic conditions do not make atoms disappear. Different organisms and pathways produce different end products.
Science / engineering practice
Constructing explanationsCore idea
Organisms cycle matter and transfer energy under different oxygen conditionsCrosscutting concept
Energy and matterEvidence and model inputs
Conceptual yeast comparison: with suitable oxygen availability, aerobic respiration can yield carbon dioxide and water; under fermenting conditions, ethanol and carbon dioxide are characteristic products. This contrasts overall processes and does not claim that every real yeast culture switches completely to one pathway. No alcohol production experiment is required.
Keep actual observations, published findings and invented model cases labeled separately. If a source or required equipment is unavailable, pause that part with a teacher; do not invent results.
Materials and preparation
Paper, graph paper or spreadsheet, and the linked readings.
Grade-level scope
Conceptual comparisons; no detailed glycolysis, electron-transport or fermentation pathway memorization.
Do the work
- Draw matched cell-boundary models for the two conditions, including organic matter input.
- Label oxygen as an input only where the described aerobic process uses it.
- Track carbon into the stated products and show usable-energy and heat pathways qualitatively.
- Explain why fermentative products can retain considerable chemical energy.
- Evaluate “without oxygen, cells cannot transfer any energy” and qualify the answer by organism and process.
Learner worksheet
Write on paper or type here and print. Entries stay in this page’s memory and are lost when you leave or reload; they are not saved or submitted.
Check your reasoning
- Does fermentation destroy carbon?
- Which process generally yields more usable energy per glucose?
- Do all anaerobic organisms make ethanol?
- Is oxygen the source of all the released energy?
Teacher review guide
Review the actual deliverable and discuss the reasoning. For each criterion, use 0 when evidence is absent or fundamentally incorrect, 1 when partly supported with a material error or omission, and 2 when accurate, supported and complete for the stated task. Maximum 8 points is a task score, not a proficiency certification. Give feedback and allow revision.
- Explains both aerobic and anaerobic conditions.
- Accounts for matter in each model.
- Compares energy transfer without a false zero-energy claim.
- Recognizes pathway and organism differences.
Answer guidance for the reasoning checks
Does fermentation destroy carbon?
No. Carbon remains in products such as ethanol and carbon dioxide in this example.
Which process generally yields more usable energy per glucose?
Aerobic respiration compared with fermentation.
Do all anaerobic organisms make ethanol?
No. Products and pathways vary.
Is oxygen the source of all the released energy?
No. Energy accounting concerns the full reactant-to-product transformation.
Access, support and extension
Offer read-aloud support, labeled diagrams, larger print or an oral/recorded explanation while preserving the scientific reasoning. A partner or teacher can handle physical manipulation while the learner plans, records and interprets. Use a teacher-provided measured dataset only when its provenance and limitations are explicit; it does not replace conducting an investigation when that is the assessed practice. For greater independence, remove prompts and ask learners to compare a second explanation or test another justified revision.
Sources and standard reference
- Official NGSS HS-LS2-3 performance expectation — inspect the practice, core idea, crosscutting concept and assessment boundary.
Instructional text and hypothetical cases are original. Linked source readings supply published evidence where specified. Teachers should judge fit with their course and state requirements.