NEB Class 12 • Biology • Plant Physiology • Practice Set

Ascent of Sap, Transpiration & Guttation Practice Set: NEB 12 Biology

Master Ascent of Sap, Transpiration and Guttation through clear concepts, representations, a reliable answer method and exam-focused practice.

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Concepts · Worked reasoning · NEB practice

Quick answer: Water ascends mainly through cohesion–tension generated by transpiration, aided by adhesion and continuous xylem columns; guttation releases liquid water through hydathodes under root pressure.

Worked practice

Build the result from meaning, not memory

Water ascends mainly through cohesion–tension generated by transpiration, aided by adhesion and continuous xylem columns; guttation releases liquid water through hydathodes under root pressure.

Worked example

On a humid night with low transpiration and positive root pressure, droplets at leaf margins can be guttation rather than dew.

The governing relationship is Transpiration rate responds to stomatal conductance, humidity, temperature, wind and water supply; distinguish vapour loss from liquid guttation. 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 a pump pushes water to tall tree tops, confusing dew with guttation, or treating transpiration as always harmful.

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.

StageQuestionEvidence
ModelWhat is idealised?Assumption stated
RepresentationWhich diagram fits?Labels or balanced equation
CalculationWhich relation follows?Symbols then SI values
EvaluationDoes it make sense?Unit, sign and trend check

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.

Questions students ask about Ascent of Sap, Transpiration and Guttation

What is the central idea of Ascent of Sap, Transpiration and Guttation?

Water ascends mainly through cohesion–tension generated by transpiration, aided by adhesion and continuous xylem columns; guttation releases liquid water through hydathodes under root pressure.

Which equation should I remember?

Transpiration rate responds to stomatal conductance, humidity, temperature, wind and water supply; distinguish vapour loss from liquid guttation.

How should I begin a numerical?

Draw the situation, list known quantities in SI units, choose the governing relation symbolically, substitute once and finish with a unit and reasonableness check.

What is a common exam mistake?

Saying a pump pushes water to tall tree tops, confusing dew with guttation, or treating transpiration as always harmful.

How can I practise this topic?

Alternate one concept explanation, one diagram and two numericals. Revisit errors after a day instead of only rereading the solution.

Where can I get tuition support?

For online or physical KTM Tuition classes, call 9846662070. After Grade 12, the MKS Education panel below gives preparation and pre-counselling contacts.

Frequently asked questions

References and next steps

Scope checked against CDC Nepal; concept support from an institutional reference and OpenStax Science. Continue with the Ascent of Sap, Transpiration and Guttation cluster.

NEB +2 tuition support

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