1. This PPT covers …. National 4 National 5
Key Area 1 Animal and plants species depend on each other
Investigate various biotic factors, e.g. food availability, predators, disease and competition. Use sampling techniques e.g. transect and quadrat analysis
Key Area 3 Sampling Techniques and measurement of abiotic and biotic factors
Plants and animals using techniques including quadrats and pitfall traps
Evaluation of limitations and sources of error in the use of quadrats and pitfall traps
Measuring abiotic factors including light intensity, temperature, pH and moisture

2. Biotic and Abiotic Factors
Quick Question
Biotic and Abiotic Factors
Relating to living things
Relating to NON -living things
Sort the following into Biotic and Abiotic factors.
Predation
Light Intensity
Rainfall
Disease
Grazing
Temperature
Food availability pH
Competition

3. Sampling Techniques and measurement of abiotic and biotic factors
National 5 Biology
Key Area 3:
Sampling Techniques and measurement of abiotic and biotic factors
National 4 Biology
Key Area 1:
Animal and plant species depend on each other: Sampling

4. By the end of the lesson you will be able to …..
National
4 outcomes
By the end of the lesson you will be able to …..
Explain why we sample ecosystems
Describe use to use sampling techniques to sample organisms from different ecosystems

5. Sampling an Ecosystem Why bother?
Find out what animals and plants live there
Find out how abundant (rare/common) they are
56.7cm
Worlds Smallest Snake found on Caribbean island of Barbados
Worlds Longest Insect found in the remote rainforests of Borneo.

6. Each type of ecosystem requires a different sampling technique
The techniques used to investigate the organisms are known as sampling techniques
Each type of ecosystem requires a different sampling technique
Soil ecosystem
Freshwater ecosystem
Tree ecosystem

7. Tree Beating Organisms and Ecosystems sampled:
Invertebrates on lower tree branches
Possible Sources of error:
Some organisms may:
miss the tray
fly away
not be dislodged
Precautions:
Use a large tray and quickly transfer sample to a bag.
Collect any remaining organisms by hand

8. Pitfall trap Organisms and Ecosystems sampled :
Invertebrates on the surface of the ground
Possible Sources of error:
Birds may eat trapped animals
Some animals may eat others
Precautions:
Disguise the opening with a ‘lid’ to stop birds eating the sample
Check traps regularly or put a preservative liquid (ethanol) in the bottom

9. Tullgren Funnel Invertebrates in the soil or in leaf litter
Organisms and Ecosystems sampled :
Invertebrates in the soil or in leaf litter
Possible Sources of error:
Soil sample may be too thick and may still contain many organisms at the end of the experiment
 Sieve mesh may be too fine and some animals may fail to fall through
Precautions:
Make the layer of soil thin or keep the trap set up for a longer period of time
Use a mesh with larger size holes.

10. Water net Organisms and Ecosystems sampled :
Organisms in freshwater stream or pond
Possible Sources of error:
Small animals may escape through the holes of the mesh
When looking for animals at the bottom of the pond, animals from the surface may have been caught from the water near the surface as the net passed through
Precautions:
Choose the net with finer mesh
Rotate the handle to close the opening of the net for the way up and down

11. Quadrat Used in which ecosystem: Samples plants in fields
Possible Sources of error:
Sampler may throw quadrat at the plants they wish to sample (results would be biased)
Part of the plant may be half in or half out
Precautions:
Throw randomly and repeatedly throughout sample area
Make a rule and decide whether plants should be counted in or not and everyone should follow it

12. “Sampling Techniques homework 1” Complete all questions

13. Can you now …. Explain why we sample ecosystems
National
4 outcomes
Can you now ….
Explain why we sample ecosystems
Describe use to use sampling techniques to sample organisms from different ecosystems
Could do whiteboard quiz on the terms or ask the pupils to make flashcards to reinforce the vocabulary

14. A. Tree dwelling caterpillar
Quick Question
1. Match the organism to the sampling technique
A. Tree dwelling caterpillar
1. Pitfall Trap
B. Dandelion
2. Quadrat
C. Minnow (small fish)
3. Tree beating
D. Beetle
4. Water net
2. Can you suggest one precaution for each sampling technique?

15. By the end of the lesson you will be able to …..
National
4&5 outcomes
By the end of the lesson you will be able to …..
Explain why we should measure abiotic factors
Describe use to measure abiotic factors in an ecosystem

16. Measuring Abiotic Factors
Examples of abiotic factors:
Moisture
Light Intensity pH
Temperature
Abiotic factors, such as moisture or light levels, will determine where organisms can live.
E.g. some plants can only survive in areas of high light intensity

17. Moisture Possible Sources of error:
Moisture from a previous measurement may be left on the probe and affect the next reading
Precautions:
Wipe and dry the probe between readings

18. Light Intensity Possible Sources of error:
The observer may cast a shadow on the light meter
Light intensity may change depending on cloud cover
Precautions:
Stand well back from meter
Take all reading as near to the same time as possible

19. pH Possible Sources of error:
Soil may remain on the probe after taking a reading giving a false result for the next sample
Precautions:
Clean and dry the probe between readings

20. Temperature Possible Sources of error:
Probe may remain at previous temperature
Precautions:
Allow probe to return to air temperature between readings

21. “Sampling and identifying living things from different habitats”
Key Area Assessment
You are now ready for your next National 3 Key Area Assessment
This will be one question on Key Area 1
“Sampling and identifying living things from different habitats”
This will be done during your next lesson

22. Quadrat Sampling Quadrats: Quadrat 1 2 3 4 5 6 7 8 9 10 Name of Plant
_______

23. Abiotic Factors Survey
Key points to remember:
Set up different meters correctly
Wipe the probe after each reading
Make sure no-one is casting a shadow over the light meter
Area number 1 2 3 4 5
Light Intensity reading
Soil Moisture reading
pH value

24. Can you now …. Explain why we should measure abiotic factors
National
4 outcomes
Can you now ….
Explain why we should measure abiotic factors
Describe use to measure abiotic factors in an ecosystem
Could do whiteboard quiz on the terms or ask the pupils to make flashcards to reinforce the vocabulary

25. Quick Question 1. Match the error and the precaution
1. Throw it randomly and repeatedly for reliable unbiased results
A. Overshadowing the meter
2. Make sure everyone is standing well away from the meter
B. Moisture from the last reading is still on the probe
C. Quadrat only thrown at parts of the field with daisies in it
3. Use a lid to hide the trap from birds
D. Birds have eaten all of the sample in a pitfall trap
4. Dry probe with tissue between readings