IB ESS Formulas
Net primary productivity - correct answer ✔✔calculated by subtracting respiratory
losses (R) from gross primary productivity (GPP).
NPP = GPP - R
Gross secondary productivity (GSP) - correct answer ✔✔the total energy or biomass
assimilated by consumers and is calculated by subtracting the mass of fecal loss
from the mass of food consumed
GSP = food eaten - fecal loss
Net secondary productivity (NSP) - correct answer ✔✔calculated by subtracting
respiratory losses (R) from GSP.
NSP = GSP - R
CBR (crude birth rate) - correct answer ✔✔= no of births / population size x1000
CDR (crude death rate) - correct answer ✔✔=# of deaths / population size x 1000
NIR (natural increase rate) - correct answer ✔✔= CBR - CDR/10 (migration is
ignored)
TFR (total fertility rate) - correct answer ✔✔= average no of children/woman
DT (doubling time) - correct answer ✔✔= time in years to double the population size
Respiration - correct answer ✔✔glucose + oxygen -> carbon dioxide + water
