7.4 populations in ecosystems

Question 1

5 steps of capture mark release method

Answer 1

capture a sample
mark them
release them and give time for distribution
capture a second sample and count total and also record the number or marked individuals
calculate the size of population

Question 2

equation to calculate size of population

Answer 2

(number of organisms initially captured x number of organisms in second sample) / number of marked organisms recorded

Question 3

6 assumptions of the capture mark release method

Answer 3

1. The proportion of marked to unmarked individuals in the second is the same as the proportion or marked to unmarked in the population as a whole
2. once released the individuals distribute themselves evenly amongst the population
3. populations has a boundary (no immigration/emigration)
4. No deaths / births
5. mark is non-toxic and not harmful to the animals survival
6. mark does not rub off

Question 4

define succession

Answer 4

the process by which an ecosystem changes over time due to abiotic factors

Question 5

define primary succession

Answer 5

the starting point on bare ground such as rock

Question 6

define secondary succession

Answer 6

a community is damaged and the soil is left, plants the colonise

Question 7

define climax community

Answer 7

a stable immunity where no further succession occurs

Question 8

2 pioneer stages of succession

Answer 8

1. a species colonises a new land surface
2. seeds and spores are blown in the wind and begin to grow

Question 9

7 steps of succession

Answer 9

• conditions become less hostile
• species diversity increases
• communities become more complex
• more habitats are formed
• more food sources become available
• organisms tend to be bigger and live longer as they become better adapted to the conditions and out-compete existing species
• increases biomass