19.2 — factors effecting populations

Question 1

populations are dynamic. what does this mean?

Answer 1

they change over time in both size and composition

Question 2

how can population size and composition be presented?

Answer 2

a population growth curve

Question 3

what are the three stages of the population growth curve?

Answer 3

1. period of slow growth — initially, as the birth rate exceeds the death rate, the population starts to grow
2. period of rapid growth — the population expands exponentially when there are no significant restrictions on its growth
3. stable state — eventually, external factors (limiting factors) stop further growth, leading to a stable population size

Question 4

what are the X and Y axes of a population growth curve graph?

Answer 4

X = time

Y = population size

Question 5

what is carrying capacity?

Answer 5

the maximum population size an ecosystem can sustainably support

Question 6

what occurs when a population reaches carrying capacity?

Answer 6

1. birth and death rates equalise
2. population growth starts to slow down and the population size stabilises
3. if the environmental conditions degrade, the population size might decrease, sometimes drastically

Question 7

what are limiting factors?

Answer 7

conditions that prevent populations from increasing indefinitely by restricting access to essential resources

Question 8

what are biotic examples of limiting factors?

Answer 8

competition, predation and disease

Question 9

what are abiotic examples of limiting factors?

Answer 9

availability of light intensity, water and space