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Grade 9 · unit review

Review: Biomolecules and Enzymes

Connect molecular structure to biological functions and reaction catalysis.

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Bring the unit skills together

Use these 4 new cases to check your reasoning. Choices are temporary and are not saved to an account, sent to staff or recorded as school grades. Download your current review choices before leaving or reloading.

Unit review questions
1. Which scientific label fits the specifically described step or feature? Supplied case: Cellulose contains sugar-derived repeating units.
Need a hint?
  • Look for the described feature: sugars and related structural or energy molecules.
  • Compare the given mechanism with the other labels; do not infer unmentioned events.
2. Which scientific label fits the specifically described step or feature? Supplied case: Molecule converted in enzyme reaction.
Need a hint?
  • Look for the described feature: molecule acted on by enzyme.
  • Compare the given mechanism with the other labels; do not infer unmentioned events.
3. Supplied case 5: product model-molecule count=120; duration (s)=15, using the explicitly named quantities. Average product rate equals product molecules in model count divided by seconds. What result follows?
Need a hint?
  • Average product rate equals product molecules in model count divided by seconds.
  • Model counts are not actual single-molecule measurements.
4. Which scientific label fits the specifically described step or feature? Supplied case: Only solution pH differs.
Need a hint?
  • Look for the described feature: only pH changes.
  • Compare the given mechanism with the other labels; do not infer unmentioned events.

The download contains your current choices and any checked feedback. Keep the separate transfer-task work in your own document; downloading its instructions does not mark it complete.

Use the skills in a new task

Create a four-panel explanation for “Biomolecules and Enzymes” using one supplied case from each lesson. Include the observation, scientific mechanism or calculation, result and a limitation. You may draw and speak your explanation; all inputs are supplied.

Work on paper or in your own document. Explain the choices you made.

  • Use one supplied case from each of the four lessons.
  • Name the relevant structure, quantity or process in every panel.
  • Show calculations with units or a causal evidence chain.
  • Distinguish source facts from fictional classroom data.
  • State a model limit or a condition that would change the result.
Compare with a model response

Panel 1: A model cell loses its starch store but retains DNA and membranes. What is directly affected? Which inference or prediction is best supported? Result: The supplied carbohydrate energy-storage role, not every molecular function.. Reasoning: Different molecular groups can serve different roles; removal does not replace every function. Model limitation: only the stated classroom boundary and supplied observations are established; unmeasured real-world performance remains unverified. Panel 2: A catalyst lowers the activation barrier but reactant/product energy levels stay fixed. What follows? Which inference or prediction is best supported? Result: The reaction can proceed faster without changing its overall energy difference.. Reasoning: Catalysis changes pathway barriers under conditions, not thermodynamic endpoint difference. Model limitation: only the stated classroom boundary and supplied observations are established; unmeasured real-world performance remains unverified. Panel 3: Supplied case 1: product model-molecule count=48; duration (s)=6, using the explicitly named quantities. Average product rate equals product molecules in model count divided by seconds. What result follows? Result: 8 model molecules/s. Reasoning: Substitute the supplied values: (48)/(6) = 8 model molecules/s. Divide product count by duration. Rate comparisons require matched conditions. Model limitation: only the stated classroom boundary and supplied observations are established; unmeasured real-world performance remains unverified. Panel 4: Trial A and B have equal substrate, enzyme and pH but differ in temperature. What can this comparison better isolate? Which inference or prediction is best supported? Result: A temperature effect under those matched conditions.. Reasoning: Holding relevant conditions fixed improves attribution within the tested range. Model limitation: only the stated classroom boundary and supplied observations are established; unmeasured real-world performance remains unverified.

A different response can also meet the criteria. Compare the evidence and reasoning, rather than copying the wording.