NEET-XII-Biology
13: Organisms and Populations
- #6If a population growing exponentially double in size in 3 years, what is the intrinsic rate of increase (r) of the population?
Ans : A population grows exponentially if sufficient amounts of food resources are available to the individual. Its exponential growth can be calculated by the following integral form of the exponential growth equation:
Nt = No ert
Where,
Nt= Population density after time t
NO= Population density at time zero
r = Intrinsic rate of natural increase
e = Base of natural logarithms (2.71828)
From the above equation, we can calculate the intrinsic rate of increase (r) of a population.
Now, as per the question,
Present population density = x
Then,
Population density after two years = 2x
t = 3 years
Substituting these values in the formula, we get:
⇒ 2x = x e3r
⇒ 2 = e3r
Applying log on both sides:
⇒ log 2 = 3r log e
Hence, the intrinsic rate of increase for the above illustrated population is 0.2311.