NEB Class 11 • Biology • Ecology • Concept Guide

Food Chains, Food Webs & Ecological Pyramids: NEB Class 11 Biology Guide

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

ConceptsWorked reasoningNEB practice

Core concept

What Food Chains, Food Webs and Ecological Pyramids means physically

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

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%.

The institutional reference gives the wider physical model; the CDC curriculum determines the NEB boundary.

Worked checkpoint with interpretation

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.

Do not stop at the number. State what the sign, ratio, spacing, frequency or direction means. A common error is 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.

Stage	Question	Evidence
Model	What is idealised?	Assumption stated
Representation	Which diagram fits?	Labels or balanced equation
Calculation	Which relation follows?	Symbols then SI values
Evaluation	Does 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.

Frequently asked questions

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.

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.

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