Intrinsic Rate of Natural Increase — NEET Biology
📚 Practice ConceptThe r in this equation is called the 'intrinsic rate of natural increase' and is a very important parameter chosen for assessing impacts of any biotic or abiotic factor on population growth.
Which of the following statements regarding population attributes and growth are correct? S1. The intrinsic rate of natural increase (r) is a crucial parameter for assessing impacts of biotic and abiotic factors on population growth. S2. In a newly colonized habitat, immigration typically contributes more significantly to population growth than birth rates. S3. Population density is always best measured by total numbers, as it is the most appropriate and easily adoptable measure for all species. S4. The Verhulst-Pearl Logistic Growth model shows an exponential phase initially, followed by a lag phase, then deceleration. S5. If population density N at time t is 20, birth rate (b) is 0.4, death rate (d) is 0.1, and there are no immigration or emigration, then dN/dt is 6.
View solution & NCERT explanation
Correct answer: A — S1, S2 and S5 only
The question assesses understanding of population attributes and growth models from NCERT Chapter 11. S1. Correct. The intrinsic rate of natural increase (r) is defined as (b-d) and is stated as 'a very important parameter chosen for assessing impacts of any biotic or abiotic factor on population growth.' S2. Correct. NCERT states, 'For instance, if a new habitat is just being colonised, immigration may contribute more significantly to population growth than birth rates.' S3. Incorrect. NCERT mentions that total number is not always the most appropriate measure. For example, for a single huge banyan tree versus 200 carrot grass plants, percent cover or biomass is more meaningful. Also, for huge populations like bacteria, counting is difficult. S4. Incorrect. The logistic growth curve shows an initial lag phase, followed by phases of acceleration and deceleration, and finally an asymptote, not an initial exponential phase followed by a lag phase. S5. Correct. Given dN/dt = (b-d)N. Here, N=20, b=0.4, d=0.1. So, dN/dt = (0.4 - 0.1) * 20 = 0.3 * 20 = 6. Therefore, statements S1, S2, and S5 are correct. The final answer is A because S1, S2, and S5 are correct statements, while S3 and S4 contain inaccuracies as per the NCERT text.
What does NCERT say about r this equation called?
Has this concept appeared in NEET?
Which chapter is this from?
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