Ecosystems

Question 1

What is Nitrogen Fixation ?

Answer 1

• N2 gas in atmosphere converted to NH3 (ammonia)

Question 2

What bacteria do N2 fixation ?

Answer 2

• Rhizobium = found in root nodules of leguminous plants
• Azotobacter = free-living in soil

Question 3

what is nitrification ?

Answer 3

NH4+ ——-> N02———>N03-

Question 4

what bacteria does NH4+ to N02-

Answer 4

nitrosomonas

Question 5

what bacteria does n02- —–>n03-

Answer 5

nitrobacter

Question 6

what is denitfirification + what conditions are needed ?

Answer 6

nitrates in soil converted to nitrogen gas happens under anaerobic conditions eg.waterlogged soil

Question 7

Outline how the percentage efficiency of energy transfer between producers and herbivores
can be estimated.

Answer 7

• collect samples of producer + herbivore from the same area
• calculate dry mass
• calculate energy content of both
• comsumer/producer ernergy *100

Question 8

define producer + consumer

Answer 8

producer = plants= photosynthesise to make own food
consumer= feeds on other organisms

Question 9

difference between pioneer + climax community

Answer 9

• pioneer less stable/lower biomass comapred to climax

Question 10

difference between decomposition + denitrification

Answer 10

• decomposition = break down of dead matter
• denitrification = conversion of nitrates to nitrogen gas

Question 11

conservation + preservation difference

Answer 11

• conservation = active management of ecosystem to maintain biodiversity
• preservation = leaving it undisturbed

Question 12

what is the order of the N cycle ?

Answer 12

• nitrogen fixation
• ammonification
• nitrification
• denitrification

Question 13

what is ammonification ?

Answer 13

• nitrogen compounds from dead plants / animals is turned into ammonia
• by decomposers

Question 14

what are 2 other methods of nitrogen fixation ?

Answer 14

• n2 fixation by lightning
• n2 fixation by haber processes

Question 15

what is water logged soil ?

Answer 15

• air spaces filled with water so no O2 available

Question 16

what are physiological , behavioural + anatomical adaptations ?

Answer 16

• behavioural = way organism acts
• physiological = processes inside body that aid survival
• anatomical = structural features that help aid survival

Question 17

What is primary succession ?

Answer 17

• colonisation of previously lifeless / uncolonized area
• eg . no soil + ONLY bare rock

Question 18

outline the stages of primary succession ?

Answer 18

• pioneer species eg. lichens posses adaptations ( can fix N2 gas , photosynthesis ) that help colonise hostile area
• pioneer species alter abiotic conditions by forming soil
• soil holds water allows other plants eg. shrubs to grow
• pioneer species may be outcompeted by others
• cycle repeats until climax community reached ( higher biodiversity + more stable )

Question 19

what is secondary succession ?

Answer 19

• takes place on land that has been previously colonised but damaged in some way eg. wildfires

Question 20

what is deflected succession ?

Answer 20

• succession is stopped due to human interference eg. use of pesticides ,herbicides ,fertilisers , grazing

Question 21

what is plagioclimax ?

Answer 21

result of deflected succession