Question

Which of the following is an important parameter for assessing the impact of any biotic or abiotic factor on population growth ?

• A. Birth rate
• B. K-carrying capacity
• C. Death rate
• D. r-Intrinsic rate of natural increase

Hint:

The parameter that combines birth and death effects on growth is r, the intrinsic rate of natural increase.

Answer 1

The Correct Option is D

Step 1: Recall the idea:
Any biotic or abiotic factor that affects a population does so by changing its births, deaths, immigration or emigration.
The intrinsic rate of natural increase, r, brings these effects into one value. It is the per capita rate of increase.

Step 2: Link it to the factors:
The value of r differs for each species and changes with conditions. For example, r for the Norway rat is 0.015 and for the flour beetle it is 0.12.
So changes in r show how strongly a factor affects the growth of the population.

Step 3: Check the options:
(A) Birth rate alone ignores deaths. (C) Death rate alone ignores births.
(B) K is the upper limit the environment can support, not the growth rate under a given factor.
(D) r combines birth and death and is the accepted parameter.

Final Answer:
The intrinsic rate of natural increase (r) is the important parameter. The correct option is (D).