Population size

Question 1

What is a limiting factor in terms of population size?

Answer 1

• a limiting factor is an environmental resource or consraint that limits population grow
  
  • e.g. avilability of food

Question 2

What are the 3 main phases of a population growth curve?

Answer 2

• phase 1
  
  • period of slow growth
  • small numbers initially reproduce
  • birth rate > death rate - increases
• phase 2
  
  • a period of rapid growth
  • number of breeding individuals increase, population multiplies exponentially
  • no constraints act to limit the population explosion
• phase 3
  
  • a stable state
  • further population growth is prevented by enternal constraints
  • population size fluctuates but ovarall size remain relatively stable
  • birth rate approx equal to death rate

Question 3

How are limiting factors divided?

Answer 3

• abiotic
  
  • e.g. temp, light, pH, humidity
• biotic
  
  • predators, disease, competition

Question 4

What is the carrying capacity?

Answer 4

• max population size that an environment can support is known as its carrying capacity

Question 5

How does migraion affect population size?

Answer 5

• immigration
  
  • movement to a particular area
• emigration
  
  • movement away from an area

Question 6

What are density independant factors?

Answer 6

• factors that have an effect on the whole population regardless of its size
• these can dramaticcaly change population size
  
  • e.g. earthquakes, fires, volcanoes, storms
• remove whole population from region