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

Current NCERT chapter

Academic session 2026-27, Chapter 11 in the current curriculum.

Welcome to the NCERT Solutions for Class 12 Biology - Chapter Organisms and Population. This page offers a step-by-step solution to the specific question from Exercise 1, Question 6: If a population growing exponentially double in size in 3 years, what is the intrinsic rate of increase (r) of the population?. With detailed answers and explanations for each chapter, students can strengthen their understanding and prepare confidently for exams. Ideal for CBSE and other board students, this resource will simplify your study experience.

Question 6: 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.

Study Tips for Answering NCERT Questions:

NCERT questions are designed to test your understanding of the concepts and theories discussed in the chapter. Here are some tips to help you answer NCERT questions effectively:

  • Read the question carefully and focus on the core concept being asked.
  • Reference examples and data from the chapter when answering questions about Organisms and Population.
  • Review previous year question papers to get an idea of how such questions may be framed in exams.
  • Practice answering questions within the time limit to improve your speed and accuracy.
  • Discuss your answers with your teachers or peers to get feedback and improve your understanding.

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Comments

  • Mehak Tanwar
  • Jul 18, 2019

Thank you so much

  • Saumya
  • Mar 12, 2019

Thank you🙏

  • Md Asad Jilani
  • Mar 23, 2018

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

  • Ravinder
  • Feb 08, 2018

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

  • garima
  • Jun 17, 2016

Thanks a lot 😊

  • riya garg
  • May 10, 2015

yupp i did the same...

  • Vinod Bharadwaj
  • Apr 14, 2015

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

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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....

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