Population Size And Ecosystems

Question 1

Climax community

Answer 1

A stable community that undergoes no further change

Question 2

Pioneer species

Answer 2

The first species to colonise a new area in the ecological succession e.g mosses and lichens in primary succession

Question 3

Succession

Answer 3

The progressive changes in the structure and species composition in a community over time

Question 4

Competition exists between:

Answer 4

1. Different species where each may occupy a different niche
2. Individuals of the same species which is density dependent i.e competition increases with population size

Question 5

Mutualism

Answer 5

An interaction between organisms of two species from which one benefits but the other is not affected

Question 6

Commensalism

Answer 6

An interaction between organisms of two species from which one benefits but the other is not affected

Question 7

Carbon cycle

Answer 7

Absorbed by photosynthesis
Returned by respiration
Added to air via combustion of fossil fuels
Deforestation affecting amount being taken in by photosynthesis
Detritivores and decomposers feee on every trophies level as they respire, carbon dioxide is refined to the atmosphere
Compression
Erosion of rocks

Question 8

Human impact on the carbon cycle

Answer 8

Deforestation - reduces photosynthesis
Combustion majority - greenhouse effect enhanced
Leads to..
global warming
Polar ice melt- higher sea levels- coastal flooding- increase temperature- forest fires- desertification

Climate change

Question 9

4 main processes in the nitrogen cycle

Answer 9

Ammonification
Nitrification
Denitrification
Nitrogen fixation

Question 10

Human impact on nitrogen cycle 2

Answer 10

Pesticides that damage crops and use nitrogen based fertilisers e.g ammonium nitrate - improve plant growth
Eutrophication - algal bloom - blocks light to aquatic plant
….
only bacteria survives releasing ammonia, methane and hydrogen sulphide, creating an environment toxic to most aerobic organisms

Question 11

Reducing use of fertilisers

Answer 11

1. Apply fertilisers when plants are actively growing, this increases their uptake reducing build up in soil
2. Not apply fertilisers with 10m of watercourses
3. Dig drainage ditches to collect any run off