If a population growing exponentially do | Class 12 Biology Chapter Organisms and Population, Organisms and Population NCERT Solutions

Question: If a population growing exponentially double in size in 3 years, what is the intrinsic rate of increase (r) of the population?
Answer:

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

Intrinsic Rate Of Increase

Hence, the intrinsic rate of increase for the above illustrated population is 0.2311.


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Comments

  • Mehak Tanwar
  • 2019-07-18 22:09:19

Thank you so much


  • Saumya
  • 2019-03-12 19:32:36

Thank you🙏


  • Md Asad Jilani
  • 2018-03-23 09:54:53

It's value of e not of loge 0.434 is nothing but value of loge


  • Ravinder
  • 2018-02-08 06:38:56

Sir can u tell me log e value is 2.7 nd log 3 is 0.4 bt here 3 * 0.434 why?


  • garima
  • 2016-06-17 22:59:36

Thanks a lot 😊


  • riya garg
  • 2015-05-10 01:16:56

yupp i did the same...


  • Vinod Bharadwaj
  • 2015-04-14 17:03:49

The “r”is the specific growth rate ( dN/Ndt ) when population growth is exponential. ( Population becomes 2 from 1 in three years. dN= 2, N=1 and dt = 3 ) By putting the values we get 2/ 1x3 = 0.66, it is so simple


Comment(s) on this Question

Welcome to the NCERT Solutions for Class 12 Biology - Chapter . This page offers a step-by-step solution to the specific question from Excercise 1 , Question 6: If a population growing exponentially double in size in 3 years, what is the intrinsic rate of incre....