Mnemonics: Ecosystem | Biology Class 12 - NEET PDF Download

1. Upright vs. Inverted Pyramids

Types: Number Pyramid, Biomass Pyramid, Energy Pyramid
Mnemonic: "Nice Big Elephants"
Breakdown:

• Nice → Number Pyramid (upright in grasslands/forests, inverted in tree-based ecosystems)

• Big → Biomass Pyramid (upright in forests, inverted in aquatic ecosystems)

• Elephants → Energy Pyramid (always upright, never inverted)

Orientation Mnemonic: "Energy Never Inverts, Biomass Sometimes, Numbers Rarely"

• Energy Never Inverts: Energy pyramid is always upright.

• Biomass Sometimes: Biomass pyramid is inverted in aquatic ecosystems (e.g., phytoplankton < zooplankton).

• Numbers Rarely: Number pyramid is inverted in tree-based ecosystems (e.g., one tree supports many insects).

2. Steps of Decomposition

Steps: Fragmentation, Leaching, Catabolism, Humification, Mineralisation
Mnemonic: "Funny Lions Can Hunt Mice"
Breakdown:

• Funny → Fragmentation (detritivores break detritus into smaller particles)

• Lions → Leaching (water-soluble nutrients wash into soil)

• Can → Catabolism (enzymes degrade detritus into simpler substances)

• Hunt → Humification (formation of humus, a nutrient reservoir)

• Mice → Mineralisation (microbes release inorganic nutrients)

3. Detritus Food Chain (DFC)

Components: Dead Matter, Decomposers, Degradation, Nutrient Return
Mnemonic: "Dead Days Decompose Deeply"
Breakdown:

• Dead → Dead Matter (detritus, starting point of DFC)

• Days → Decomposers (fungi, bacteria break down detritus)

• Decompose → Degradation (breakdown into simpler substances)

• Deeply → Nutrient Return (nutrients recycled to producers)

4. Grazing Food Chain (GFC)

Components: Producers, Primary Consumers, Secondary Consumers, Tertiary Consumers
Mnemonic: "Green Goats Make Meat"
Breakdown:

• Green → Producers (plants, start of GFC)

• Goats → Primary Consumers (herbivores, e.g., goats)

• Make → Secondary Consumers (primary carnivores, e.g., frogs)

• Meat → Tertiary Consumers (top carnivores, e.g., snakes)

Tip to Remember:

• GFC starts with Green (living plants).

• DFC starts with Dead (non-living organic matter).