Use the photosynthesis carbon ratio

Supplied materials

• All measurements and observations below are supplied classroom examples. They are not data from actual learners or a claim about a particular real site.
• Paper or browser document; an ordinary calculator is optional.
• Rule: Carbon-dioxide molecules required equal six times modeled glucose molecules. Formula: 6*a. Variable key: a = modeled glucose-molecule count
• Distinct worked inputs and result: A distinct model makes 7 glucose molecules: 6×7=42 carbon-dioxide molecules supply the carbon.
• Assessment case 1: Supplied case 1: modeled glucose-molecule count=2, using the explicitly named quantities. Carbon-dioxide molecules required equal six times modeled glucose molecules. What result follows?
• Assessment case 2: Supplied case 2: modeled glucose-molecule count=3, using the explicitly named quantities. Carbon-dioxide molecules required equal six times modeled glucose molecules. What result follows?
• Assessment case 3: Supplied case 3: modeled glucose-molecule count=4, using the explicitly named quantities. Carbon-dioxide molecules required equal six times modeled glucose molecules. What result follows?
• Assessment case 4: Supplied case 4: modeled glucose-molecule count=5, using the explicitly named quantities. Carbon-dioxide molecules required equal six times modeled glucose molecules. What result follows?
• Assessment case 5: Supplied case 5: modeled glucose-molecule count=6, using the explicitly named quantities. Carbon-dioxide molecules required equal six times modeled glucose molecules. What result follows?
• Assessment case 6: Supplied case 6: modeled glucose-molecule count=8, using the explicitly named quantities. Carbon-dioxide molecules required equal six times modeled glucose molecules. What result follows?

Learn the idea

In the simplified balanced overall photosynthesis equation, six carbon-dioxide molecules supply the six carbons of one glucose molecule. Use molecule counts only; actual mechanisms involve multiple steps.

Carbon-dioxide molecules required equal six times modeled glucose molecules. The formula in the supplied model is 6*a. Variable key: a = modeled glucose-molecule count. Count six carbon atoms per glucose. Do not infer a direct one-step mechanism.

A distinct model makes 7 glucose molecules: 6×7=42 carbon-dioxide molecules supply the carbon. This ratio alone omits water, oxygen and energy details. Track the quantity and unit before calculating. Explain the meaning of a positive, negative or fractional result when relevant. A numerical answer supports the stated model calculation; broader claims require the additional measurements and assumptions described here.

1. Name the measured quantities and their units before substituting values.
2. Write the stated rule and use the variable key to match each symbol to its explicitly named quantity.
3. Calculate each supplied case separately, keeping intermediate arithmetic and the result unit.
4. Explain the result in context and identify the assumption that would invalidate direct use of the rule.

Check your reasoning

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Take it further

Changed-input task: use the same stated model with modeled glucose-molecule count=3. Expected result: 18 CO₂ molecules. Explain what changes and keep this assumption: This ratio alone omits water, oxygen and energy details.

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