ECO-01 Key Numbers & Data for NEET

10% — Lindeman's efficiency / 10% law: percentage of energy transferred from one trophic level to the next
90% — Energy lost as heat at each trophic level (metabolic work, incomplete assimilation, respiration)
K/2 (= N/2 at inflection) — Population size at which maximum growth rate occurs in logistic model
K — Carrying capacity: maximum sustainable population in a given environment
0 — Growth rate (dN/dt) when N = K in logistic model; population is at equilibrium
r = b − d — Intrinsic rate of natural increase = birth rate − death rate
Nt = $N_{0}$ e^(rt) — Exponential growth integrated formula (e = Euler's number, ≈ 2.718)
71% — Percentage of Earth's carbon stored in ocean reservoirs as dissolved $CO_{2}$
1000+ years — Time for primary succession from bare rock to climax forest (can extend to millennia)
3–4 — Number of NEET questions per year reliably from ecology chapter (historically consistent)
5 steps — Decomposition: Fragmentation, Leaching, Catabolism, Humification, Mineralization (FLCHM)
6 types — Population interactions: Mutualism, Competition, Predation, Parasitism, Commensalism, Amensalism
4 strategies — Organism responses to abiotic stress: Regulate, Conform, Migrate, Suspend
3 pyramid types — Numbers, Biomass, Energy (only energy is always upright)
2 food chain types — Grazing food chain (living plants) and detritus food chain (dead organic matter)
1 gaseous phase absent — Phosphorus cycle: no atmospheric reservoir (contrast with C and N cycles)
+/+, −/−, +/−, +/0, −/0 — Signs for mutualism, competition, predation/parasitism, commensalism, amensalism
60 million acres — Land overrun by Opuntia (prickly pear cactus) in Australia before biological control
GPP − R = NPP — Net Primary Productivity formula; R = respiration by producers