Question

In a pond, last year there were 30 lotus plants. Through reproduction, 25 new lotuses were added in one year while 8 plants died. The birth and death rates for the lotus populations respectively are______ and _______ individuals per lotus per year.
A. 0.83, 0.26
B. 0.26, 0.83
C. 0.25, 0.80
D. 0.80, 0.25

Answer 1

Hint: The ability of an individual of a population to produce a new individual is called natality or birth rate of individuals of a certain population while mortality (or death rate) refers to death of individuals in the population.

Complete answer:
In last year the total number of lotus plant = 30
This year new added lotus plants by reproduction = 25
This year died lotus plants in the pond = 8
Let us calculate the birth rate
Birth rate of a population = $\dfrac{New added plants}{Total number of plants in the beginning}$
Hence birth rate of population = $\dfrac{25}{30}$
Death rate of the population = $\dfrac{total number of dead plants}{total number of plants in the beginning}$
Hence death rate of the population = $\dfrac{8}{30}$
The birth rate of lotus plants in a certain pond is 0.833 and the death rate in the same pond is 0.26, so as per the above calculations.
So, the correct answer is “Option A”.

Additional Information:
The size of a population is represented by its fundamental property called density. Density is referred to as the total number of individuals per unit area or volume at a given time. Two types of densities are described crude density and specific (ecological) density.

Note:
The Crude density is the density per unit total space and specific or ecological density is the density per unit of habitat space i.e. available area or volume that can actually be colonized by population.