Photosynthesis: Light, C3 & C4 Practice Set: NEB 12 Biology

Worked practice

Build the result from meaning, not memory

Photosynthesis captures light energy in thylakoid reactions to make ATP and NADPH, then fixes carbon in the Calvin cycle; C4 plants first concentrate carbon through a four-carbon pathway.

The governing relationship is Overall carbon fixation is commonly summarized as 6CO₂+6H₂O→C₆H₁₂O₆+6O₂, while ATP and NADPH couple the light reactions to carbon reduction. Check the convention, geometry or boundary condition before calculation.

Independent practice ladder

1. Define the key physical quantities and give their SI units.
2. Draw and label the relevant wave, ray, mode or energy diagram.
3. Recalculate the worked example after changing one input by a factor of two.
4. Explain the result without equations.
5. Create a Nepal-relevant situation such as a classroom speaker, musical pipe, optical slit or thermal machine.
6. Compare two cases and predict the larger output before calculating.
7. Find and repair one deliberately wrong sign, node or unit.
8. Write a three-mark answer and a five-mark answer.

Answer protocol: diagram → known data → principle → symbolic equation → SI substitution → result → physical check. Saying oxygen comes from carbon dioxide, treating the dark reaction as night-only, or claiming C4 plants are always superior.

NEB answer method

Model → evidence → equation → check

First identify the system and what the question asks. Label the diagram, apparatus or reaction with SI quantities, then state the principle before selecting an equation. Solve symbolically where possible and check units, limiting cases and chemical or physical meaning.

Make the idea concrete in Nepal

Connect the model to a school laboratory, household technology, health, environment, energy or local material. The example should clarify the science rather than merely mention a place. Compare a prediction with an observation and record uncertainty.

Review the NEB Class 12 Biology revision roadmap and the complete Biology guide. For online or physical tuition, call 9846662070.

Frequently asked questions

Questions students ask about Photosynthesis: Pigments, Light Reaction, C3 and C4 Pathways

References and next steps

Scope checked against CDC Nepal; concept support from an institutional reference and OpenStax Science. Continue with the Photosynthesis: Pigments, Light Reaction, C3 and C4 Pathways cluster.