Scientific Investigation

Question 1

Accuracy

Answer 1

The closeness of a measured value to a standard or known value

Question 2

Precision

Answer 2

The closeness of two or more measurements to each other

Question 3

Representative Sample

Answer 3

A sample from a larger group that accurately represents the characteristics of a larger population

Question 4

Random sampling

Answer 4

Individuals all have the same probability of being selected and are chosen randomly

e.g. using random co-ordinates for soil samples

Question 5

Systematic sampling

Answer 5

selecting members of the population at regular intervals - every nth person

usually used along a transect

e.g. temp when climbing a hill

Question 6

Stratified sampling

Answer 6

Dividing a population into subpopulations based on specific characteristics - must take a proportional sample (in ratio)

Question 7

What is important when determining sample size?

Answer 7

large enough to be representative of the whole population

Question 8

What is a standardised sampling method and why is it important?

Answer 8

a method that allows data to be collected the same way by different people at different times

controlling variables

Question 9

What is a line transect?

Answer 9

a line or route that we stop upon and take a measurement at regular intervals

systematic sampling

Question 10

How is a belt transect used?

Answer 10

using quadrats

can be interrupted or continuous

Question 11

What is an abundance scale?

Answer 11

a way of applying observations to a category

Question 12

DAFOR abundance scale

Answer 12

dominant
abundant
frequent
occasional
rare

Question 13

Limitations of abundance scales

Answer 13

categorisation is subjective
no numbers = no statistics can be calculated
possibility of incorrect identification

Question 14

Open frame quadrat

Answer 14

square frame
placed on top of vegetation
random/systematic sampling
count number of singular or different species
counting can be subjective an inaccurate

Question 15

Grid quadrat

Answer 15

like an open frame but divided into squares
random/systematic sampling
used for calculating % cover - 100 squares

Question 16

Point quadrat

Answer 16

T-shaped frame
10 long pins, plants that are hit by the pins are identified and counted
useful for tall plants and uneven ground
may damage vegetation

Question 17

Kick sampling

Answer 17

Place net on river bed, agitate sediment, allow organisms to flow into the net
net must be downstream
used to study freshwater invertebrates
force of kicks may vary
organism may be damaged

Question 18

Surber sampler

Answer 18

Net is directly connected to the site of disturbance, agitate sediment inside the square
net must be downstream
used to study freshwater invertebrates
unable to use if riverbed is uneven

Question 19

Colonisation media

Answer 19

Provide an ideal habitat for the organism you want to count, wait for organism to colonise
inaccurate as only some of the population will colonise it

Question 20

Pitfall trap

Answer 20

Dig hole, insert container (top must be ground level), cover top with slate propped on pebbles, return, count and identify
monitors terrestrial animals that live on ground surface
animals may crawl out/eat each other
if preservation fluid is used it may attract/repel specific organisms

Question 21

Sweep net

Answer 21

Sweep net in figure of 8, set amount of times
captures organisms that live on/in vegetation
some may die when caught
organisms can fly out

Question 22

Beating tray

Answer 22

Beat trees/vegetation and catch fallout
some organisms may not be dislodged
some species may fly away
difficult to standardise strength of beatin

Question 23

Light trap

Answer 23

Used to catch flying organisms
identify, count, release
may escape before counting
different species are attracted to different wavelengths of light
some don’t fly in rainy conditions

Question 24

Tullgren funnel

Answer 24

Collect soil/litter sample, place in container and turn on light (heat source), organisms move away from the light and fall through the grid into the collecting pot
heat may kill organism
some organisms may be too large for the grid
some species are not repelled by light/heat

Question 25

Earthworm extraction

Answer 25

Mimic rainfall (stamping), flood area, add irritant to water, dig up soil and hand sort
sampled randomly using a quadrat
worms may die
worm may burrow deeper
permeability of soil affects method

Question 26

Indirect monitoring methods

Answer 26

GPS collar
sound recorder
camera trapping
fecal sampling
satellite imagery/drones
identification of tracks

Question 27

Population size/density

Answer 27

estimate the numbers of organisms of a particular species within a population or area

Lincoln index can be used

sometimes possible to count all organisms

Question 28

Abundance scales

Answer 28

allocating species to a category depending on their abundance

allows many areas to be studied quickly

DAFOR scale

Question 29

Species richness/diversity

Answer 29

measure the number of different species in an area

standardised by using specific sample areas

Question 30

Species frequency

Answer 30

measure of the dispersal of a species by recording its proportion

high species frequency = generally distributed

Question 31

Species density

Answer 31

the number of species found to a specific area

Question 32

Percentage vegetation cover

Answer 32

estimated by observing proportions

ground covered by vegetation/ sky observed by vegetation

grid quadrats are commonly used

Question 33

Lincoln Index equation

Answer 33

N = n1 x n2/ m

n1 = first capture
n2 = second capture
m = number of organisms in common (how many are marked in n2)
N = population estimate

Question 34

What is lincoln index also known as?

Answer 34

capture, mark, release, recapture

Question 35

What is the Lincoln index used for?

Answer 35

estimate the population of a given organism based on two independent sets of observed cases