Paper 2 Research Methods

Question 1

Describe the process of using pitfall traps to measure invertebrate populations

Answer 1

Container placed in hole in ground with its open end making a close fit with the soil and top being level with ground surface
A cover is supported over the opening to exclude predators that may eat animals that are caught, and to prevent flooding by rain

Question 2

Describe the process of using a beating tray

Answer 2

Sheet/tray placed beneath vegetation which is beaten several times with a stick
Invertebrates that are dislodged fall onto the sheet and are collected for identification and counting

Question 3

Name 4 limitations when using pitfall traps

Answer 3

Only works for mobile animals
Trapped carnivores may predate on other organisms
Preservative may attract/repel certain species
Some species may avoid trap or escape

Question 4

Name 4 limitations of using a beating tray

Answer 4

Difficult to standardise the method between researchers
Some species are not dislodged
Thicker branches shake less
Higher branches cannot be reached

Question 5

Describe the process of surber sampling in three steps?

Answer 5

Fixed area of riverbed is sampled within a box like frame
The riverbed is disturbed and stones are inspected manually
Netting at the side of the net opening reduces number of organisms that escape
Standardised mesh size of nets

Question 6

Name two limitations in surber sampling

Answer 6

Can be only used where the water flow is fast enough to carry organisms
Difficult to set on rough substrates in deep water

Question 7

Describe the process of earthworm soil pit extraction in two steps

Answer 7

Chosen area depth is dug, eg 0.5m times 0.5m times 0.5m
Irritant is added, eg mustard water, influencing worms to come to the surface
The soil is hand sorted and worms collected

Question 8

Describe the process of using a sweep net to measure invertebrate populations and name one limitation to this method

Answer 8

Net is swept through the vegetation
Same number of sweeps of same length
(Mobile species may escape)

Question 9

Briefly outline the process of using an aerial insect net to study invertebrates

Answer 9

Capture flying insects such as butterflies
Limitations:mobile species may escape