AS Unit 1 & 2 Practical

Question 0

What is null hypothesis?

Answer 0

The theory that there is no link or relationship between variables

Question 1

What’s the difference between independent and dependent variables?

Answer 1

Independent variable is deliberately altered or measured to see if it affects the dependent variable ( i.e. The results that are measured)

Question 2

What are 3 main sampling methods?

Answer 2

random sampling : to minimise bias in an area (eg random coordinates)
Systematic sampling : chosen using a pattern or grid
Stratified sampling : if area has clear sub areas then study each individually and then combine results

Question 3

What are key sampling considerations?

Answer 3

Number of samples
Sampling location ( determines which 3 approaches to use)
Standardised sampling methods
Timing ( eg seasonal variation due to migration)

Question 4

What is a quadrat?

Answer 4

An area usually square or circular in which samples are taken

Question 5

What are pitfall traps?

Answer 5

A method of sampling animal populations by collecting them when they fall in traps such as plastic cups

Question 6

What equipment might you need to sample wildlife?

Answer 6

Measuring tape
Light meter
Noise level meter
Quadrat
Flow meter ( measures buoyancy time)
Beating tray 
Pitfall traps
Wind velocity measure

Question 7

Homogenous

Answer 7

Evenly mixed

Question 8

What determines size of quadrat?

Answer 8

Habitat being studied ( larger things have bigger ones so dunes > insects )
several small ones sometimes better than big one to show patchy distribution
If many organisms on border you may need larger one or need consistent approach, eg include two sides in results.

Question 9

How do you calculate biodiversity?

Answer 9

Simpson’s index
D = N (N-1) / n (n-1)

d is diversity index
N is number of individuals in all species
N is number of particular species

High D means high biodiversity

Question 10

Belt transact

Answer 10

A strip of land sampled with quadrants spaced at regular intervals ( gives % cover of a species)

Question 11

Line transact

Answer 11

Samples taken at points along a line eg soil temperature or light levels (NOT species)

Question 12

DAFOR abundance scale

Answer 12

D dominant
A abundant
F frequent
O occassional
R rare

Qualitative scale where detailed numbers not needed

Question 13

Lincoln index

Answer 13

A catch, mark, release, recapture method of estimating animal populations.
(Need to be Markable!)
Population = (no. Sample 1 x no. sample 2) / no. in second sample with marks

Question 14

Kick sampling and surber samplers

Answer 14

Sampling aquatic populations by disturbing riverbed then using a net frame (surber) to get more quantitative results than kicking alone (temporarily catches them)

Question 15

Poster

Answer 15

A mouth suction device to pick up visible invertebrates in soil

Question 16

Sweep nets

Answer 16

Large lightweight nets swept through vegetation to collect invertebrates

Question 17

Light traps

Answer 17

Mercury vapour lamps or fluorescent tubes attract flying insects

Question 18

Tullgren funnel

Answer 18

Extract invertebrates from soil / leaf litter by raising light or temperature and they move downwards into a collection chamber (need to be small and mobile)

Question 19

Earthworm populations

Answer 19

Flood soil with irritant chemical to force them to surface. (Doesn’t work for deep ones or where can go sideways)

Question 20

Bird populations

Answer 20

Tagging legs with metal rings - also used for turtles, sharks, whales, lobsters

Question 21

Indirect population monitoring

Answer 21

Nests
Footprints
Territory marks eg scratchings
Owl pellets (shows what been eating)
Otter spraints (droppings)
Samples of DNA from skin, faeces

Question 22

Soil texture equipment

Answer 22

1. Soil sieves (increasing finer mesh)
2. Sedimentation: take dry soil, crush it, half fill measuring cylinder with water, seal with bung, mix, stand. Volume of settled particles is recorded at 1 min (sand) 8 hours (silt) 5 days ( clay) and plotted on soil triangle.

Question 23

Soil organisms

Answer 23

Use poorer, Tullgren funnel and earthworm extraction

Question 24

Soil pH

Answer 24

Add 2.5cm3 soil to test tube, add barium sulphate to settle soil particles, add 3.5cm3 distiller water, add universal indicator solution, bung, shake, stand 15 mins, use pH indicator paper.

Question 25

Soil water content test

Answer 25

Heat soil so water evaporates
- collect using core sampler
- place in sealed bag to prevent evaporation
- remove larger particles/organisms
- place in pre weighed basin and heat to100 degrees C for 24 hours
- re weigh & repeat until constant weight reached
% water content = wet soil mass- dry soil mass divided by wet soil mass x 100

Question 26

Soil organic matter

Answer 26

Heat soil to burn off matter
- weigh empty crucible add dry soil sample
- heat to 500 degrees C with buses burner
- re weigh crucible & repeat until constant weight
% organic matter = (dry soil mass - burned soil mass) / dry soil mass x 100