7.4 Population In Ecosystem

Question 1

Define community

Answer 1

All the different species that live in one area and interact with each other

Question 2

Define ecosystem

Answer 2

All the living organisms found in one area, combined with non-living aspects of their environment. Can vary from very large to very small

Question 3

Describe biotic and abiotic factors, giving examples

Answer 3

Biotic = living features of an ecosystem e.g. predators,disease

Abiotic = non living features of an ecosystem e.g. light, temperature

Question 4

Define habitat

Answer 4

The place where an organism lives within an ecosystem

Question 5

Define a niche

Answer 5

The role of a species within its habitat, consisting of both its biotic interactions e.g. what it eats, and abiotic interactions e.g. time of day it’s active

Question 6

What is meant by carrying capacity

Answer 6

The maximum size of population an ecosystem can support

Question 7

Name 4 abiotic factors that affect population growth

Answer 7

Temperature
Light
pH
Water/humidity

Question 8

What is meant by intraspecific and interspecific competition

Answer 8

Intraspecific = competition between organisms of the same species

Interspecific = competition between organisms of different species

Question 9

What resources might organisms compete for?

Answer 9

Food,water,shelter,minerals,light,mates

Question 10

Describe the pattern of a typical predator-prey relationship in terms of population change

Answer 10

Prey is eaten by predator, resulting in predator population increasing and prey population decreasing

Fewer prey means increased competition for food, so predator population decreases

Fewer predators means more prey survives, and the cycle begins again

Question 11

How are quadrants used for estimating population size

Answer 11

Can be placed on grid coordinates or at intervals along a belt transect. Results reported as either percentage cover or frequency. For slow moving or non motile organism

Question 12

How is mark-release-recapture used for estimating population size

Answer 12

A sample of species is captured,marked,then released back into the same area they were caught

After a certain period of time another sample of the species is captured, and the number of marked organisms are counted

Question 13

What is the equation for mark-release-recapture

Answer 13

Estimated population size =
total number of individuals in first sample X total number of individuals in second sample
——————————————————————————————————number of marked individuals recaptured

Question 14

What assumption does the mark-release-recapture method make

Answer 14

Marked individuals distributed evenly
No migration in or out of the population
Few births or deaths
Methods of marking does not affect survival
Mark does not come off

Question 15

Why are ecosystems described as being dynamic

Answer 15

Population constantly rise and fall

Any small change can have a large effect

Biotic and abiotic factors may alter the conditions of the ecosystem

Question 16

What is meant by primary succession

Answer 16

Where an area previously devoid of life is colonised by a community of organisms

Question 17

Summarise the process of primary succession

Answer 17

Pioneer species can survive harsh conditions and colonise the area

They change abiotic factors of their environment e.g. decomposition adds nutrients to ground

Over time, this allows more complex organisms to survive

Question 18

What is the climax community and how is it reached

Answer 18

The final stage of succession, where the ecosystem is balanced and stable. It is reached when the soil is rich enough to support large trees or shrubs, and the environment is no longer changing

Question 19

How might a species alter the environment that develops during succession

Answer 19

A species may improve the environment to make it more suitable for other species. Alternatively, a species may worsen the environment by making it less suitable for other species

Question 20

Define conservation

Answer 20

The protection and management of species and habitat, in order to maintain biodiversity. Methods need to be adapted to the ecosystem in question

Question 21

How might succession be managed in order to aid conservation

Answer 21

Sometimes succession needs to be prevented in order to preserve an ecosystem at a certain point, e,g. Stopping moorland from progressing into spruce forest. This is called a plagioclimax