| Describe an Indicator Species | A species by their presence or absence indicates environmental quality |
| Describe an Indicator Species | A species by their presence or absence indicates environmental quality |
| Describe an Indicator Species | A species by their presence or absence indicates environmental quality |
| 3 examples of biotic factors | Food supply, Predation, Disease |
| 3 examples of abiotic factors | Temperature, Light intensity, Soil moisture |
| How to measure light intensity | Use a light meter
Direct sensor towards the light source
Read correct scale |
| What are the limitations and source of errors of light intensity | Light intensity could change during the sampling process - cloud cover
Light sensor could be covered by your shadow |
| What are the ways to minimise these errors of light intensity | Take all readings at the same time each day or take multiple sampling at each place and take an average
Make sure the light sensor does not have a shadow over it |
| How to measure temperature | Use a Thermometer/Temperature probe
Do not cover sensor
Read correct scale |
| What are the limitations and source of errors of temperature | Thermometer or probe may not be inserted deep enough into soil
Bulb or thermometer may be held by hand
Thermometer may be in direct sunlight |
| What are the ways to minimize these errors of temperature | Push thermometer or probe into the soil until half of it is in
Allow reading to stabilise before attempting to take reading
Do not hold bulb and ensure thermometer is in the shade when measuring air temperature |
| How to measure the PH | Use a PH meter
Place the clean probe in the soil/water
Read correct scale |
| What are the limitations and source of errors of PH | Reading may be contaminated by soil/water left on probe from previous samples
Not enough samples taken |
| What are the ways to minimize these errors of PH | Wipe probe between sampling to reduce cross-contamination
Increase numbers of samples taken |
| How to measure the Soil moisture | Use a moisture meter
Place the clean probe into the soil
Read correct scale |
| What are the limitations and source of errors of soil moisture | There may be moisture on the probe from past readings
Not enough samples taken |
| What are the ways to minimize these errors of soil moisture | Wipe probe with a paper towel before and after taking each reading
Take a repeat for each sample site and calculate an average |
| What are Quadrats used for | Plants and very slow moving organisms |
| How do you use Quadrats | They should be placed randomly so that a representative sample is taken
The number of squares where the organism is present is counted
Replicate to give a representative sample of the area |
| What are the limitations and source of errors of Quadrats | Can only be used for stationary or slow moving organisms
Depends largely on human accuracy
Incorrect identification/counting
Non-random sampling |
| What are the ways to minimize these errors of Quadrats | Use a key to make sure the organisms are correctly identified
If organisms are only in a part of the quadrat make a rule for counting them
If organisms are in a cluster increase the number of samples |
| How do you use a pitfall trap | Bury a container with drainage holes, level with the ground
Protect the trap from rain by placing a piece of raised wood or slate above the trap
Leave the trap overnight |
| What are the limitations and source of errors of pitfall traps | Only traps animals on the ground
Time consuming
Incorrect identification
Predation occurs if left to long
Non-random sampling |
| What are the ways to minimize these errors of pitfall traps | Dig the hole deep enough to ensure the trap is level with the ground
Empty trap regularly
Place small holes in the bottom to allow drainage
Use a key to identify animals |
| What is a Key used for | To enable correct identification |
| What happens when Over-Grazing occurs | Happens when the herbivore population is high. More animals feed on limited plants. Biodiversity is reduced. |
| What happens when Under-Grazing occurs | Happens when the herbivore population is low. Less plants are eaten. Biodiversity is reduced |
| What happens when Moderate-Grazing occurs | Can increase Biodiversity. Allows less dominate plants to grow as they have more light and soil nutrients |
| What happens when lots of Predation occurs | Causes prey specie diversity to fall - everything gets eaten |
| What happens when little Predation occurs | Causes prey species to compete with each other, only the best competitors survive - diversity falls |
| What happens when Moderate Predation occurs | Keeps the number of best competitors down so different species can thrive/survive - high biodiversity |
| What are aquatic environments now showing signs off | Acidification from pollution. |
| Describe Pollution and give 3 examples | Environmental pollution is contamination by a pollutant, which harms living organisms eg causes distress, disease or death |
| Describe an Indicator Species | A species by their presence or absence indicates environmental quality |
