Describe the phases of a sigmoid growth curve, including the lag and log phases, and explain the biological processes occurring in each.

a) The type of growth curve shown above is a Sigmoid growth curve (or S-shaped growth curve).

b)

i) A-B: Lag phase

ii) B-C: Log phase (or Exponential phase)

c)
A-B: During the lag phase, the population is small, and individuals are adapting to the new environment. There is a low birth rate as individuals mature and begin to reproduce, resulting in slow population growth.
B-C: During the log phase, the population has adapted to the environment, and resources (food, space) are abundant. The birth rate significantly exceeds the death rate, leading to a rapid and exponential increase in population size.