1. Factors affecting population growth
4.5

2. Population – the total number of individuals of a species in a given area

3. I + B > E + D
I + B = E + D
I + B < E + D

4. Population growth follows a sigmoidal curve:
Plenty of resources allowing a high birth rate, while the death rate is often low. This rarely happens as resources are not endless
In most natural populations as the population grows its increase will slow and it will stabilise at a level that can be supported by the environment called carrying capacity.

5. Sigmoid Growth Curve
Death Phase – Death of cells exceeds production of cells. Only seen in populations usually grown in containers.
Most natural populations oscillate around the carrying capacity.
Lag Phase:
Low numbers and therefore low rates of reproduction. Adjustment phase – enzymes being synthesised.
Log Phase: Rapid cell division or fast reproduction rate. Abundance of food / nutrients. No environmental resistance. Population doubles per unit time.
Stationary Phase: Population growth slows down, cell production = cell death. Carrying capacity has been reached. Environmental resistance is in effect – food/nutrients / oxygen / space is low and competition increase, waste products may be accumulating.

6. Factors which can affect population size

7. Competition – will occur for resources
Interspecific – Occurs between different species Intraspecific – Between members of the same species, usually more intense – why?

8. Predator Prey Relationships
Parasites and Disease Relationships