SvS Biology 2000 - Webby aw not, hewe I come...
Marking Schedule/Suggested Answers
1. The distribution, diversity and numbers of plants and animals found in ecosystems are determined by biotic and abiotic factors.
Circle the errors to the table:
Biotic Factors |
Abiotic Factors |
| Plants Soil drainage Fungus Protista Wind speed Relationships between organisms |
Light Monera Commensalism Temperature range pH Aspect and inclination |
(b)
scrape away surface leaf litter
place pinch of soil on white tile
add 5 drops universal indicator
sprinkle barium sulfate over sample
allow colour to develop and compare with colour chart
(c) water salinity
2.
| Characteristic: | Aquatic | Terrestrial |
| light availability | lower - decreases with depth | higher - unless under canopy |
| temperature range | lower | higher |
| buoyancy | higher | lower |
| gas availability | lower - decreases with depth | higher - decreases with altitude |
3. sightings, tracks, trappings, droppings
4(a) numbers can be too high for counting,
and organisms may move too quickly or
alternately hide from view.
(b) (i) random quadrat sampling
(ii) capture/recapture techniques
(c)
| random quadrat sampling | capture/recapture techniques | |
| Equipment
|
5 marker poles map of area string of determined length |
traps food bait (eg: oats, honey, peanut butter) |
|
Procedure:
|
Estimate ecosystem area size Calculate quadrat size needed Determine # quadrats required (10% of total area) Randomly select quadrat sites Set mid pole and then corner poles Count number of organisms in quadrat Repeat in all quadrats Determine density of organism (average #/total area of quadrats) Determine total numbers (density x total area of ecosystem) |
Determine ecosystem area size Determine number of traps to be used (should reflect area size) Randomly select trap sites Record time of day and climatic conditions Leave traps for specific duration (overnight) Check traps and record numbers caught Mark or tag organisms and release Reset traps using same food, location and climate, and for the same duration Re-check traps Record numbers caught Record numbers in 2nd capture with marking/tag Use formula to determing population #: (CAPTURE
x RECAPTURE) |
| Problems:
|
organisms only partly within quadrat will affect the count | organisms might "learn"
from initial capture organisms may not be lured into traps marking may affect survival of organism |
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S. van Strien