Question

The graph shows two types of population growth curve. $A$ is exponential and $B$ is logistic.

Which one of the following growth model considered as more realistic one?

• A. Exponential growth curve
• B. Logistic growth curve
• C. Both the growth curves
• D. None of the above

Answer 1

Answer: (B)

Growth model considered more realistic is logistic or sigmoid growth curve.
Sigmoid growth is density dependent and can be expressed by the following equation:
$\frac{d N}{d t} =r N \frac{(K-N)}{K}=r N\left(1-\frac{N}{K}\right)$
$ N =$ Population size
$ t =$ Intrinsic of natural increase
$ K =$ Carrying capacity
$r=$ Intrinsic rate of natural increase
$\frac{K-N}{K}=$ Environmental resistance
$N=K_{1}$ the growth rate and becomes zero and population reaches to equilibrium.