Question

(a) Name the two growth models that represent population growth and draw the respective growth curves they represent.
(b) State the basic reason for the difference in the shape of these curves.
(c) Which one of the curves represents the human population growth at present? Do you think such a curve is sustainable? Give reason in support of your answer.

Answer 1

There are two models which describes the pattern of growth in a particular population. They are as follows-
1. Exponential growth model: Here, the population increase over time as a result of the number of individuals available to reproduce without regard to resource limits. The Population size increases at an exponential rate over time, continuing upward.

2. Logistic growth model: The growth of most population depends at least in part on the available resources in the environments. So, more realistic population growth model is the logistic growth model where population increases exponentially till it reaches the carrying capacity in the environment.
(b) The exponential phase, gives J shape graph while sigmoid shape, is obtained in case of logistic growth. The shape of the curve differs in the two models as because in the exponential growth the population grows by fixed percent at regular intervals and the growth increases exponentially with time irrespective of the resources. In the logistic growth, the population increases at the onset and continues exponentially till the mid when the resources are utilized at maximum level. The graph becomes stationary when the population exceeds its carrying capacity.
c) The graph for the exponential model represents the current population because nowadays the population has exceeded its carrying capacity. Such kind of population growth is not sustainable because the resources of energy are limited and are about to extinct in near future which may pose threat to the upcoming generation.