Populations And Their Growth Flashcards
What are the factors that make ecosystems dynamic?
- Biological cycles e.g. Nitrogen
- Habitats change as succession occurs
- New species arrive and some die
What is the lag phase in a one step growth curve?
It is a period of adaptation or prep for growth e.g. Rabbits waiting to get to sexual maturity to reproduce
What is the log phase?
When the population doubles per unit time because there is nothing limiting growth.
What environmental resistance factors stop the lag phase being maintained indefinitely?
- Less food
- Waste products increase and become toxic
- Not enough space for nesting
- Overcrowding
- Competition
What is the stationary phase in the one step growth curve?
It means the population has reached its carrying capacity and fluctuates around this.
What is the death rate in the one step growth curve?
Death rate is larger than birth rate
What is a predator prey relationship?
As prey increase, predators increase. Therefore prey decrease, so predators decrease. Therefore prey increase, the the cycle continues.
What is a density dependent factor?
They are biotic. A factor that has a greater effect on the population if it is more densely populated. E.g. Disease, parasitism and depletion of food supply.
What is a density independent factor?
They are abiotic. Factors that don’t depend on population size.
Describe negative feedback.
If the optimum population increases, there is raised environmental resistance, leading to a fall back to optimum population. If there is a fall in optimum population, there is decreased environmental resistance, leading to an increase to optimum population.
