6.3.1 - Ecosystems

Question 1

Ecosystem

Answer 1

All the living organisms found in area and the non living aspects of their environment
Interactions between abiotic and biotic facts = dynamic

Question 2

Biotic factors

Answer 2

Living features of an organism

EG predators, disease

Question 3

Abiotic factors

Answer 3

Non-living features of an ecosystem

EG light, temp

Question 4

Biomass + how is it transferred?

How to measure it

Answer 4

Total weight of living matter in a certain area, transferred through tropic levels through consumption

Measured in terms of mass of C, dry mass of tissue

Question 5

Efficiency of biomass transfer

Answer 5

Efficiency = (biomass transferred/ biomass intake) * 100

Question 6

How can human activities affect biomass transfer

Answer 6

light, water, temp maximised
Increased nutrients in soil
Pests + weeds removed
Growth rates boosted through steroids and selective breeding

Question 7

Roles of Microorganisms in N cycle

Answer 7

Nitrogen fixing bacteria convert N(g) into ammonia
EG rhizobium in roots, Azotobacter in soil

Nitrifying bacteria convert ammonium compounds into nitrates
(Nitrosomonas) and then into nitrates (Nitrobacter)

Question 8

Organism in C cycle

Answer 8

Respiration of plants + animals add CO2 into atmosphere

Photosynthesis of plats removes CO2 from atmosphere

Decomposers (microorganisms) decay plant + animal material into CO2

Question 9

primary succession

Answer 9

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

Question 10

Process of primary succession

Answer 10

Pioneer species are able to survive harsh condition + colonise the area

They die + decompose, add nutrients to the group

Over time allows more complex organisms to survive

Question 11

Climax community

Answer 11

Final stage of succession, ecosystem is balanced and stable

Soil is rich enough to support large trees and shrubs + the environment is no longer changing

Question 12

Deflected succession

Answer 12

Succession interrupted, usually by human interference

Question 13

Sampling

Answer 13

Selecting a group of individuals that will represent the whole target population

Allow to meander the distribution + abundance of organisms

Question 14

Sampling methods

Answer 14

Quadrants

• small areas
• randomly/regularly placed across habitat
• frequency or % cover calculated

Transects

• larger areas
• sample taken along line that crosses the habitat
• combined w quadrants in form of belt transect

Question 15

Carrying capacity

Answer 15

Max population size that a habitat can support

Defined by presence of limiting factors