(a) Arithmetic growth- In arithmetic growth, one of the daughter cells continues to divide, while the other differentiates into maturity. The elongation of roots at a constant rate is an example of arithmetic growth.
(b) Geometric growth- Geometric growth is characterised by a slow growth in the initial stages and a rapid growth during the later stages. The daughter cells derived from mitosis retain the ability to divide, but slow down because of a limited nutrient supply.
(c) Sigmoid growth curve- The growth of living organisms in their natural environment is characterised by an S shaped curve called sigmoid growth curve. This curve is divided into three phases – lag phase, log phase or exponential phase of rapid growth, and stationary phase.
Exponential growth can be expressed as: 𝑊1=𝑊₀eʳ ͭ
Where, e = Base of natural logarithms
𝑊₁= Final size
𝑊₀= Initial size
𝑟= Growth rate
𝑡= Time of growth

(d) Absolute and relative growth rates- Absolute growth rate refers to the measurement and comparison of total growth per unit time. Relative growth rate refers to the growth of a particular system per unit time, expressed on a common basis.

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