6.3 Ecosystems

Question 1

nitrogen cycle

Answer 1

• plants cannot use nitrogen directly so NITROGEN FIXATION occurs. can occur during lightening strikes or through Haber process in making fertilizers. Mainly nitrogen-fixing bacteria such as Azobacter and Rhizobium are used. Rhizobium has a mutallistic relationship with the plant as it provides them with nitrogen whilst the plant provides the bacterium with carbon compounds. nitrogen becomes ammonium ions or nitrate ions
  -AMMONIFICATION= nitrogen compounds from dead organisms are turned into ammonia by decomposers which turns into ammonium ions
• NITRIFICATION= chemoautotrophic such as Nitrosomonas bacteria in the soil get energy by oxidising ammonium ions into nitrites and some nitrites into nitrates such as Nitrobacters
  -Denitrification= denitrifying bacteria converts nitrates back to nitrogen gas. when bacteria is growing in anaerobic conditions such as waterlogged soils they use nitrates as a source of respiration and produce nitrogen gas and nitrous oxides

Question 2

carbon cycle

Answer 2

-Carbon dioxide in the air is absorbed by plants during photosynthesis and respiration.
-carbon is passed to the primary consumers when they eat the plant. and secondary and tertiary when they eat consumers
-decomposers digest on dead organisms
-if organic matter end up in places where decomposer arent there they their carbon content can be turned into fossil fuels an relased when the fuels are burned
-rocks can also be formed by organic matter deposited on sea floors e,g, limestone and chalk which is mainily CACO (tres). this carbon can be released by the movement of tectonic plates

Question 3

ecosystems

Answer 3

-all interacting living organisms and non-living factors within an area

Question 4

Habitat

Answer 4

-the place where an organisms lives

Question 5

community

Answer 5

• all the populations of different species, who live in the same place at the same time,and who can interact with each other

Question 6

consumers

Answer 6

-an organisms that eats other organisms, e.g. animals, rocks

Question 7

producer

Answer 7

-an organism that produces organic molecules using sunlight e.g, plants

• convert light energy to chemical energy

Question 8

trophic level

Answer 8

• a stage in a food chain occupied by a particular group of organisms, e.g. producers are the first tropic level in a food chain

Question 9

abiotic factors that affect ecosystems

Answer 9

-oxygen availability
-light
-temperature
-water availability
-type of soil

Question 10

biotic factors

Answer 10

-predation
-competition= interspecific - between different species
intraspecific- within the same species
-diseases

Question 11

rock pools

Answer 11

-Biotic factors may be seaweed which is a food source, competition can limit the number of organisms present
-Abiotic factors= tides. high tides= PH,temperature, salt conc(salinity) similar to ocean ecosystems due to the submersion
-low tides=higher salinity and temperatures which is more extreme and only a few organisms can tolerate

Question 12

playing trees

Answer 12

• biotic=producers large amount of plants which may attract a large amount of animals which use them as food source
  -abiotic=rainfull and sunlight. wet year= waterlogged soil =poor plant growth which may decrease th number of consumers

Question 13

large trees

Answer 13

-biotic factors= insects which consume the leaves of trees. if they consume all the leaves they can slow tree growth and lead to death
-abiotic= drought conditions (continuous low rainful) can negatively impact growth of trees and lead to death

Question 14

trophic level order

Answer 14

-producers,primary consumers,secondary consumers,tertiary consumers

Question 15

why is efficiency of biomass transfer never one hundred percent

Answer 15

• sunlight reflected
  -only ten percent of sunlight is used in photosynthesis
  -some energy lost in respiration as thermal energy
  -energy lost in excretion. some food is indigestible
  -not all parts of food are eaten

-food parts not eaten are recycled in the ecosystem by decomposes

Question 16

how can human manipulate biomass transfer

Answer 16

-keep animals indoor= less energy lost in respiration
-give animals food with high energy contents
-vaccinate animals so they use less energy killing pathogens
-genetic engineering/selectively breed animals so they are disease resistant
-grow plants in greenhouses increases photosynthesis=increase biomass production
-harvest plants earlier=longer growing season

Question 17

how to calculate/measure biomass transfer

Answer 17

-collect sample
-kill organisms
-heat in a oven at 80 degrees
-constantly check mass until a constant mass is obtained.

effeciency=bisomass transfered/biomass intake x one hundred

same as biomass at higher tropic level/biomass at a lower tropic level

Question 18

primary succession

Answer 18

=organism colonies a lifeless habitat e.g. bare rock

Question 19

secondary succession

Answer 19

=organism recolonize developed ecosystems

Question 20

process of succession

Answer 20

• pioneer species are are able to survive harsh conditions such as algae and lichens begin to live on bare rock
  -they die and decomposers break them down. erosion of the rock and build up of dead and organic mater produce enough soil for larger plants to grow, which replace/succeed the algae and lichens
  -in the same way larger plants succeed theses small plants, until a final stable community is reached=climax community

Question 21

deflected succession

Answer 21

• when succession is stopped or interfered

e.g. humans mowing grass to create a golf course. if left unmown succession would occur and climax community met.