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IB Knowledge Statements
IB Knowledge Statements
See Topic 2 Ecology Page
Part 1: What are Biotic and Abiotic Factors?
Part 1: What are Biotic and Abiotic Factors?
Take a look at the photograph on the left, everything that you see and might not see can be the factors for an ecosystem to be self-sustaining
Let's list down what present in this ecosystem! We can clearly see a ladybug, aphids and some vegetation. These are living things are are interacting with each other in many different ways. These living things are now categorised as the biotic factors.
What we can't see in this photograph is non-living factors or components or also known as the abiotic factors. These are essential parts of an ecosystem to be sustaining. For example, the vegetation requires water, CO2 and light to carry out photosynthesis. In addition, it also requires nutrients such as nitrates and phosphates from the soil to grow. On the other hand, the animals require oxygen to respirate (the plants also respirate in the dark). The relative humidity and temperature in this ecosystem seem to be at the optimal level for this ecosystem to self-sustain itself
Take a look at the following different biomes with their biotic and abiotic factors
Estuaries are classified as marine ecosystems because they have high salt content compared to freshwater. Mixing of freshwater and oceanic seawater leads to a diluted salt content but one that is still high enough to influence the distribution of organisms within it. Salt-tolerant animals and plants have specific adaptations to help them cope with the osmotic demands of saltwater.
In sum, the abiotic factors can be summarised as follows:
Marine Ecosystem
Marine Ecosystem
salinity
pH
temperature
dissolved oxygen (O2)
soil texture
Freshwater Ecosystem
Freshwater Ecosystem
turbidity
pH
temperature
dissolved (O2)
flow velocity
light intensity
Terrestrial Ecosystem
Terrestrial Ecosystem
temperature
light intensity
wind speed
soil texture
slope/aspect
soil moisture
drainage
soil mineral content
In overall, all abiotic factors can be measured. The measurement are often quantitative but sometimes can be qualitative. Quantitative measurement is often more preferred as this will allow data interpretation using graphical methods that show patterns
Part 2 [Skills]: Evaluating measures of abiotic factors
Part 2 [Skills]: Evaluating measures of abiotic factors
In overall, all abiotic factors can be measured. The measurement are often quantitative but sometimes can be qualitative. Quantitative measurement is often more preferred as this will allow data interpretation using graphical methods that show patterns
Read this reading material and evaluate the measuring tools to measure some abiotic factors. The following example is an evaluation (pros and cons)
2.1.1 Measuring Abiotic Factors.pdf
Temperature
Temperature
Standard tool: Thermometer with probes (connected to a datalogger)
The temperature needs to be taken at a standard depth.
Problems arise if the thermometer is not buried deeply enough so the depth needs to be checked each time it is used.
Temperature can only be measured for a short period of time when using conventional digital thermometers.
Dataloggers can be used to measure temperature over longer periods of time (i.e. days or years) and monitor fluctuations in temperature.
Evaluate Measures of Abiotic Factors.wavEvaluate the measures of describing abiotic factors [4]
P/S: You will need to use these skills and evaluation in your experimental IA. Essential Question: How to measure abiotic factors correctly?
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