Human Excretory System Practice Set: NEB 12 Biology

Worked practice

Build the result from meaning, not memory

The urinary system filters blood, regulates water, ions, acid–base balance and pressure, and removes nitrogenous wastes through kidneys, ureters, bladder and urethra.

The governing relationship is Nephron function links glomerular filtration, selective tubular reabsorption, secretion and excretion; excretion=filtration−reabsorption+secretion. 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. Calling urine simply filtered blood, confusing ureter with urethra, or assuming kidneys only remove urea.

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 Human Excretory System

References and next steps

Scope checked against CDC Nepal; concept support from an institutional reference and OpenStax Science. Continue with the Human Excretory System cluster.