6.6.1 what determines population size?

Question 1

carrying capacity

Answer 1

maximum population size that can be maintained over period in a particular habitat

Question 2

limiting factor

Answer 2

factor whose magnitude slows down rate of a natural process

Question 3

3 phases of population growth (of individual species)

Answer 3

1. lag phase
2. log phase
3. stationary phase

Question 4

describe lag phase (1)

Answer 4

• may only be few individuals
• still acclimatising to habitat
• rate of reproduction is low
• growth in pop. size is slow

Question 5

describe log phase (2)

Answer 5

• resources are plentiful
• conditions are good
• reproduction can happen quickly & exceeds mortality
• pop. size increases rapidly

Question 6

describe stationary phase (3)

Answer 6

• pop. size levelled out at carrying capacity of habitat
• rate of reproduction & mortality = equal
• pop. size stays stable/fluctuates slightly in response to small environmental variations

Question 7

density independent limiting factors

Answer 7

act just as strongly, irrespective of size of pop.

eg. low temp may kill same number of individuals in population no matter the size

Question 8

density dependent limiting factors

Answer 8

= factor influences population more strongly as pop. size increases
- the carrying capacity is the upper limit these factors place on pop.

eg. availability of resources like food, water, shelter may decrease