BiologyChapter 15: Ecology
Ecological Pyramids and Energy
Energy pyramid: always narrower up (heat loss, ~10% school transfer).
Learning objectives
- Explain ecological pyramids and energy in clear biological language.
- Distinguish 1. why 10% from 2. gpp and npp.
- Use the key terms to answer a short Federal Board exam question.
Definition
Energy pyramid: always narrower up (heat loss, ~10% school transfer). Biomass pyramid: usually up-narrow; a pond may invert with tiny fast algae. Number pyramid: one tree can invert the numbers (many insects). Units: kJ m^-2 y^-1 for energy. GPP: total photosynthate. NPP: GPP minus plant respiration. NPP is what is available to herbivores.
Important terms
- ECOLOGICAL PYRAMIDS AND ENERGY
- Energy pyramid: always narrower up (heat loss, ~10% school transfer).
- 1. WHY 10%
- Not every part is eaten.
- 2. GPP AND NPP
- GPP = NPP + R_plant.
Overview
Three pyramids, one rule for energy:
Why 10%
Not every part is eaten. Digestion is incomplete. Respiration heat. The 10% is a teaching average, not a law of 10.000%.
Examples Short chains feed more people in the school tale · Meat is a higher trophic cost · Decomposers get the rest
Gpp and Npp
GPP = NPP + R_plant. Ocean and rainforest as high NPP regions named. Desert low. Crop NPP is a human-managed number, not a fertiliser recipe.
Examples kJ units · Pyramid of energy: kJ · Numbers: count of heads
WHAT — ECOLOGICAL PYRAMIDS AND ENERGY
Energy pyramid: always narrower up (heat loss, ~10% school transfer). Biomass pyramid: usually up-narrow; a pond may invert with tiny fast algae. Number pyramid: one tree can invert the numbers (many insects). Units: kJ m^-2 y^-1 for energy. GPP: total photosynthate. NPP: GPP minus plant respiration. NPP is what is available to herbivores.
WHY — Why this topic matters
ECOLOGICAL PYRAMIDS AND ENERGY is an independent FBISE learning unit because students must connect its structures and processes with their biological functions and examples.
HOW — How it works
WHY 10%: Not every part is eaten. Digestion is incomplete. Respiration heat. The 10% is a teaching average, not a law of 10.000%. Examples: Short chains feed more people in the school tale; Meat is a higher trophic cost; Decomposers get the rest. GPP AND NPP: GPP = NPP + R_plant. Ocean and rainforest as high NPP regions named. Desert low. Crop NPP is a human-managed number, not a fertiliser recipe. Examples: kJ units; Pyramid of energy: kJ; Numbers: count of heads. Worked 10%: 1000 kJ in producers. About 100 kJ to herbivores (school). About 10 kJ to primary carnivores.
Worked example
- Worked 10%:
- 1000 kJ in producers.
- About 100 kJ to herbivores (school).
- About 10 kJ to primary carnivores.
In simple words
10% is a teaching average. No diet-cult plan.
Key points
- ~10% school
- energy pyramid never inverts
- heat and waste
- what plants keep
Exam preparation
Exam Focus
Quick revision
Revision Zone
Review the key facts, formulas and checks before you move on.Ecological Pyramids and Energy
Sticky Notes · Quick Revision
Core Idea
- Energy pyramid: always narrower up (heat loss, ~10% school transfer). Biomass pyramid: usually up-narrow; a pond may invert with tiny fast algae. Number pyramid: one tree can invert the numbers (many insects). Units: kJ m^-2 y^-1 for energy. GPP: total photosynthate. NPP: GPP minus plant respiration. NPP is what is available to herbivores.
1. WHY 10%
- Not every part is eaten. Digestion is incomplete. Respiration heat. The 10% is a teaching average, not a law of 10.000%.
2. GPP AND NPP
- GPP = NPP + R_plant. Ocean and rainforest as high NPP regions named. Desert low. Crop NPP is a human-managed number, not a fertiliser recipe.
Exam Example
- Worked 10%:
- 1000 kJ in producers.
- About 100 kJ to herbivores (school).
- About 10 kJ to primary carnivores.
Common Misconception
- Do not treat 1. WHY 10% and 2. GPP AND NPP as the same idea; each explains a different part of the topic.
FBISE Exam Check
- Define ecological pyramids and energy, explain the two key parts, and use the correct biological terms.
- Exam reminder: Worked 10%: 1000 kJ in producers. About 100 kJ to herbivores (school). About 10 kJ to primary carnivores.
60-second revision
- Energy pyramid: always narrower up (heat loss, ~10% school transfer).
- 1. WHY 10%: Not every part is eaten.
- 2. GPP AND NPP: GPP = NPP + Rplant.
- Exam reminder: Worked 10%: 1000 kJ in producers. About 100 kJ to herbivores (school). About 10 kJ to primary carnivores.
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