NEB Class 11 • Biology • Ecology • Practice Set

Food Chains, Food Webs & Ecological Pyramids Practice Set: NEB 11 Biology

Master Food Chains, Food Webs and Ecological Pyramids through clear concepts, representations, a reliable answer method and exam-focused practice.

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Concepts · Worked reasoning · NEB practice

Quick answer: Food chains show selected feeding pathways, food webs show connected pathways and ecological pyramids compare number, biomass or energy across trophic levels.

Worked practice

Build the result from meaning, not memory

Food chains show selected feeding pathways, food webs show connected pathways and ecological pyramids compare number, biomass or energy across trophic levels.

Worked example

If producers store 10,000 kJ and herbivores receive 1,000 kJ, transfer efficiency is 10%; the remaining energy is not simply destroyed but used and dissipated.

The governing relationship is Energy pyramids are upright because usable energy decreases at each transfer; efficiency is energy at higher level divided by energy at lower level times 100%. 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. Pointing arrows toward food rather than energy recipient, assuming every biomass pyramid is upright, or using the ten-percent rule as exact.

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 11 Biology revision roadmap and the complete Biology guide. For online or physical tuition, call 9846662070.

Questions students ask about Food Chains, Food Webs and Ecological Pyramids

What is the central idea of Food Chains, Food Webs and Ecological Pyramids?

Food chains show selected feeding pathways, food webs show connected pathways and ecological pyramids compare number, biomass or energy across trophic levels.

Which equation should I remember?

Energy pyramids are upright because usable energy decreases at each transfer; efficiency is energy at higher level divided by energy at lower level times 100%.

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?

Pointing arrows toward food rather than energy recipient, assuming every biomass pyramid is upright, or using the ten-percent rule as exact.

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 Food Chains, Food Webs and Ecological Pyramids cluster.

NEB +2 tuition support

Ask about online or physical tuition

For focused Class 11 and Class 12 subject tuition, lesson clarification, worked-example practice and exam preparation, call 9846662070. Class mode, timetable, teacher availability and fees should be confirmed directly before enrolment.

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