Population

Question 1

Outline how population size is affected by natalaty, immigration, mortality and emigration

Answer 1

Population size is increased when the natalaty rate and the immigration is higher than the mortality rate and the emigration. We call it overall population change: (natalaty+immigration) - (mortality+emigration)

Natalaty means that offspring is added to a population.
Mortality means that individuals die.
Immigration means that individuals move into the area
Emmigration means that individuals move out of area

Question 2

Explain the reasons for the exponential growth phase, the plateau phase and the transitional phase between these two phases

Answer 2

Lag phase: little or no cell multiplication (low natalaty rate), a period of adaption to conditions.

Exponential growth: population increases exponentially, a period of no constraints on growth. Adequate nutrients are available and little accumulation of waste products has occurred. High natalaty rate, and low mortality rate.

Question 3

List three factors that set limits to population increase

Answer 3

• Shortage of resources
• More predators
• More diseases or parasites
• All of these become more intense as population size increases = density-dependent factors