Question

What are labelled phases A, B and C in a given sigmoidal growth curve?
A: Stationary, B: Log, C: Lag
A: Lag, B: Stationary, C: Log
A: Log, B: Lag, C: Stationary
A: Lag, B: Log, C: Stationary

Answer 1

The phases are divided as follows:
(i) Exponential growth phase
(ii) Transitional phase
(iii) Plateau phase

Step by step answer: Growth curve: A growth curve is a graphical representation of the pattern of a quantity over a time period. A sigmoidal growth curve is an exponential growth curve. It follows typically three stages, namely:Exponential growth phase, Transitional phase and Plateau phase.
The exponential growth phase is also known as Lag period, the transitional phase as Log period and the plateau phase as Stationary period. Since there are few reproductive individuals, hence in the initial stage, lag phase, population growth will be slow. The natality rate exceeds mortality rate. A major factor behind low mortality rate is the abundance of resources and lower competition.
In the log phase, the competition among the individuals increases because the resources become Limited. As a result the mortality rate begins to rise while the natality rate plummets. This leads to slowing down population growth.

Note: The stationary phase or the plateau phase is also known as asymptotic phase. During this stationary phase mortality rate becomes equal to the birth rate and the population growth becomes stationary.