6.5.1 ecosystems

Question 1

define abiotic factors

Answer 1

non-living components of an ecosystem that affect other living organisms

Question 2

define biotic factors

Answer 2

environmental factors associated with living organisms in an ecosystem that affect each other (eg. predation, disease)

Question 3

define an ecosystem

Answer 3

community of animals, plants and bacteria interrelated with the physical and chemical environment

Question 4

what scales can an ecosystem be on

Answer 4

• large scale (eg. african grassland)
• medium scale (eg. playing field)
• small scale (eg. rock pool, large tree)

Question 5

components of an ecosystem

Answer 5

• habitat
• population
• community

Question 6

define habitat

Answer 6

place where organism lives

Question 7

define population

Answer 7

all of organisms of one species, who live in small place at same time, and can breed together

Question 8

define community

Answer 8

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

Question 9

what is a niche

Answer 9

the role of each species in an ecosystem

Question 10

what could the description of an organisms niche include

Answer 10

• how/what it feeds on
• what it excretes
• how it reproduces

Question 11

what is impossible in an ecosystem

Answer 11

for 2 species to occupy the exactly same niche in an ecosystem

Question 12

biotic factors affecting ecosystems

Answer 12

1. producers (plants/some photosynthetic bacteria)
   - supply chemical energy to all other organisms
2. consumers
   - primary consumers are herbivores (feed on plants)
   - secondary consumers are carnivorous & eat primary consumers
   - secondary consumers eaten by carnivorous tertiary consumers
3. decomposers
   - eg. bacteria, fungi, some animals
   - feed on waste material & dead organisms

Question 13

abiotic factors within an ecosystem

Answer 13

• eg. pH, relative humidity, temperature, concentration of pollutants
• vary in space & time
• also include disturbance to ecosystems (eg. turbulence, storms)
• may be influenced by biotic factors
• at extreme values of an abiotic factor, a species may perform better/worse or die
• abiotic factor may have an optimum level (lethal at both extremes)

Question 14

what do we refer to ecosystems as

Answer 14

dynamic

Question 15

3 types of change within an ecosystem which affect population size

Answer 15

1. cyclic changes
   - repeat themselves in a rhythm
   - eg. tides, changes in day length, fluctuation of predator/prey species
2. directional changes
   - go in one direction
   - often last longer than the lifetime of organisms within an ecosystem
   - particular variables continue to increase/decrease
   - eg. erosion of coastline
3. unpredictable/erratic changes
   - no rhythm & no constant direction
   - eg. effects of lightning/hurricanes