Class 12th Biology 2016 Set2 Outside Delhi Board Paper Solution
(a) Name the two growth models that represent population growth and draw the respective growth curves they represent.
(b) State the basis for the difference in the shape of these curves.
(c) Which one of the curves represent the human population growth at present ? Do you think such a curve is sustainable ? Give reason in support of your answer.
(a) Two growth models are :
1. Exponential
2. Logistic
a - exponential growth curve b - logistic growth curve
1. Exponential Growth curve:
N : Population size
b : Birth rates
d : Death rates
dN / dt : increase / decrease in N during time t
(b) The difference in the shape of these curves is due to the difference in availability of resources.When resources are unlimited each species realizes its innate potential to grow in number and result in a J-shaped curve in exponential growth while in logistic growth no population has unlimited resources leads to competition for resources and show S-shaped curve.
(c) Logistic growth curve represents the human population growth at present because the number of human beings are increasing rapidly but the available resources are not increasing enough. Such a curve is not sustainable because at one point the human population would reach a place where resource there would not be finite resources for every one.
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