There are 50 lotus plants in a pond. 20 new plants were added through reproduction. The birth rate of lotus in a year is:

Question

Prepp Team · Accepted Answer

Understanding Birth Rate Calculation in Population Ecology

The question asks us to calculate the birth rate of lotus plants in a pond based on the initial population size and the number of new plants added through reproduction over a year.

In population ecology, the birth rate is a measure of how many new individuals are added to a population per unit of time, relative to the size of the population. It's often expressed as births per individual per unit time.

Calculating the Birth Rate for Lotus Plants

To calculate the birth rate, we need the number of new individuals born (or added through reproduction, as in this case with plants) and the initial population size. The formula for per capita birth rate is:

\(\text{Birth Rate} = \frac{\text{Number of births}}{\text{Initial Population Size}}\)

Let's identify the values from the question:

Initial number of lotus plants = 50
Number of new plants added through reproduction in a year = 20
Time period = 1 year

Now, we can plug these values into the formula:

\(\text{Birth Rate} = \frac{20}{50}\)

\(\text{Birth Rate} = \frac{2}{5}\)

\(\text{Birth Rate} = 0.4\)

This calculated value, 0.4, represents the number of new plants added per existing plant per year.

Comparing Calculation with Given Options

Let's look at the options provided:

(a) 0.4
(b) 30
(c) 20
(d) 2.5

Our calculated birth rate is 0.4, which matches option (a).

Summary of Lotus Plant Birth Rate

The birth rate of the lotus plants in the pond, based on the increase in population over one year, is 0.4. This means that for every existing lotus plant, 0.4 new plants were added through reproduction during that year.

Lotus Plant Population Data
Description	Value
Initial Population	50 plants
New Plants Added (Births)	20 plants
Time Period	1 year
Calculated Birth Rate	0.4 per plant per year

Revision Table: Population Ecology Terms

Key Terms in Population Ecology
Term	Definition	How it relates to the question
Population	A group of individuals of the same species living in the same area at the same time.	The lotus plants in the pond form a population.
Birth Rate (Natality)	The number of new individuals produced per unit time per individual or per unit population size.	What we calculated in the problem.
Mortality Rate (Death Rate)	The number of deaths per unit time per individual or per unit population size.	Not directly relevant to this calculation, as we only considered additions.
Population Growth Rate	The overall change in population size over time (Births - Deaths + Immigration - Emigration).	The addition of 20 plants shows population growth, but birth rate is a component of growth.

Additional Information on Population Dynamics

Population dynamics is the study of how populations change in size, density, and distribution over time. Birth rate (natality) and death rate (mortality) are two primary factors influencing population size changes. Immigration (individuals entering a population) and emigration (individuals leaving a population) are also important factors, especially in open populations like animals moving between areas.

For plants, 'birth' through reproduction might refer to the successful germination of seeds or the growth of new ramets (clones) depending on the species and context. In this question, 'new plants were added through reproduction' directly gives us the number of 'births' for the calculation.

The birth rate calculated here is a per capita rate, meaning it's per individual. It tells us the average number of offspring produced by each individual in the population during the specified time period. A birth rate of 0.4 per plant per year suggests that, on average, each lotus plant contributed to the addition of 0.4 of a new plant in that year.