Life On Earth 2- Distribution of Organisms

Question 1

Name six biotic factors which could affect the distribution of organisms in an ecosystem

Answer 1

• competition for resources
• disease
• food availability
• grazing
• predation

Question 2

List four abiotic factors which could affect the distribution of organisms in an ecosystem

Answer 2

• temperature
• light intensity
• moisture levels
• ph

Question 3

Describe how to measure light intensity, a possible source of error and how to minimise this

Answer 3

• you would use a light meter to measure light intensity
• errors would be taking the reading when in your shadow
• to minimise this you would take the reading when the light panel is not in the shade

Question 4

Describe how to measure soil moisture, a possible source of error and how to minimise this

Answer 4

• you would use a moisture meter to measure the soils moisture
• errors would be not cleaning the probe between sample sites
• to minimise this you would wipe the probe clean before testing the next site

Question 5

Describe how to measure soil temperature, a possible source of error and how to minimise this

Answer 5

• you would use a thermometer to measure the soils temp
• errors would be not putting the thermometer to the same depth at each site
• to minimise this you would the thermometer to the same depth at each sample site

Question 6

Describe how to measure soil pH, a possible source or error and how to minimise this

Answer 6

• you would use a pH meter to measure the soils pH
• errors would be not cleaning the probe between sample sites
• to minimise this you would clean the probe between sample sites

Question 7

State what type of organism could be sampled using a pitfall trap

Answer 7

bugs like beetles, ants, snails and woodlice

Question 8

State two possible sources of error when using a pitfall trap and how these can be overcome

Answer 8

• errors could be birds possibly eating trapped insects and bugs may eats eachother
• to minimise this you could disguise the opening of the trap, check the trap regularly or half fill trap with water/ethanol

Question 9

State what type of organism could be sampled using a quadrat

Question 10

State two possible sources of error when using a quadrat and how these could be overcome

Question 11

State what an indicator species is

Answer 11

this is a species that by their presence and absence indicate the quality of the environment

Question 12

Give an example of an indicator species and what it tells you about the environment

Answer 12

lichens indicate level of air pollution, blood worms in water indicate sewage pollution