6.5: Ecosystem

Question 1

Describe the differences between the following biological terms:
(a) a pioneer community and a climax community f215 june 14 q7a

Answer 1

1 pioneers arrive , before climax / earlier; [pioneers arrive first / climax arrive last]
2 pioneer communities subject to, greater/ more,
change/ succession/ replacement;
3 pioneer community (usually) has, less/ lower, biodiversity;
4 idea that pioneer community is (often) less, stable/ self-sustaining;
5 pioneer community has lower biomass;
6 [e.g. species in pioneer community better adapted to (named) abiotic factor(s) and those in climax community better adapted to (named) biotic factor(s)]

Question 2

Describe the differences between the following biological terms:
(b) decomposition and denitrification f215 june 14 q7b

Answer 2

1 decomposition is break down , dead matter / waste
or decomposition is conversion of organic matter to inorganic ; [for inorganic: carbon dioxide / CO2 / water / H2O / ammonium compounds /
ammonium ions / NH4+ IGNORE ammonia]
2 denitrification is conversion of nitrates to nitrogen (gas) ; [(NO3 - and N2)]
3 decomposition increases , mineral / nitrate , supply
and denitrification reduces , mineral / nitrate , supply ; [decomposition returns , mineral / nitrate, to soil
and denitrification removes mineral / nitrate, to soil]

Question 3

Describe the differences between the following biological terms:
(c) conservation and preservation f215 june 14 q7c

Answer 3

1 conservation maintains , ecosystem / biodiversity /
species / habitats or conservation involves , active / sustainable , management of , ecosystem / resource / habitat ; [named resource]
2 preservation leaves , ecosystems / habitats ,
undisturbed ; [unchanged/ not disrupted / no physical
intervention]

Question 4

Describe the differences between the following biological terms:
(d) nitrogen fixation and nitrification. f215 june 14 q7d

Answer 4

1 nitrogen fixation is the conversion of (atmospheric)
nitrogen into , ammonia / ammonium compounds / ammonium ions ; [N2 / NH3 / NH4+]
2 nitrification is the conversion of , ammonia / ammonium compounds /ammonium ions , into nitrite / nitrate ; [NH3 / NH4+/ NO2- / NO3-]
3 nitrogen fixation involves , Rhizobium / Azotobacter / Nostoc and nitrification involves , Nitrosomonas /
Nitrobacter;