24.1 - Population Size

Question 1

What phases can a population growth curve take?

Answer 1

• Phase 1: slow growth, small numbers reproduce, birth > death, so population increases
• Phase 2: rapid growth, breeding individuals increase, population grows exponentially, no constraints
• Phase 3: stable state, external constraints prevent growth. Population size fluctuates (limiting factors) but size remains stable, births = deaths

Question 2

What are limiting factors? Give examples of biotic and abiotic factors.

Answer 2

Limiting factors prevent further growth, and can cause it to decline. E.g resources or accumulation of waste

Abiotic: temperature, light, pH, water, oxygen
Biotic: predators, disease + competition

Carrying capacity: max population an env can support.

Question 3

What are the two types of migration?

Answer 3

Immigration:
- movement of individual organisms into a particular area increasing population size

Emigration:
- movement of individual organism away from a particular area, decreasing population size

Question 4

What are density independent factors?

Answer 4

• factors have an affect in the population regardless of size
• can dramatically change population size

E.g volcanoes, Earthquakes, flood