A growth curve is an empirical model of the evolution of a quantity over time. Growth curves are widely used in biology for quantities such as population size or biomass, individual body height or biomass. Values for the measured property can be plotted on a graph as a function of time;\xa0Two types\xa0of population growth patterns may occur depending on specific environmental conditions: An exponential growth pattern (J curve) occurs in an ideal, unlimited environment. A logistic growth pattern (S curve) occurs when environmental pressures slow the rate of growth.