There are 50 lotus plants in a pond. 20 new plants were added through reproduction. The birth rate of lotus in a year is:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 0.4
Birth rate = new individuals added ÷ original population = 20 ÷ 50 = 0.4 per lotus per year.
Option (1) 0.4 — Correct. Birth rate is the number of births per individual over a period. Here 20 new plants came from 50 plants, so the birth rate = 20 ÷ 50 = 0.4 offspring per lotus per year.
NCERT Extract:
Population Attributes – “… A population has certain attributes whereas, an individual organism does not. An individual may have births and deaths, but a population has birth rates and death rates. In a population these rates refer to per capita births and deaths. The rates, hence, expressed are change in numbers (increase or decrease) with respect to members of the population. Here is an example. If in a pond there were 20 lotus plants last year and through reproduction 8 new plants are added, taking the current population to 28, we calculate the birth rate as 8/20 = 0.4 offspring per lotus per year.”