Food Chains and Food Web
Which part of the food web should we focus on?
This science revision note aims to help your child
– predict the population change of other organisms in a food web
– with so many organisms in a food web, what should your child do?
– Proper explanation using the correct scientific keywords.
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The food web below shows the relationship between Organisms A, B, C and D.
A new population of organism E is introduced to the community. Organism E feeds on C. How will the population of Organism D be affected? Explain your answer.
STEP 1
Draw the food relationship between E and C on the diagram.
STEP 2
Predict what happens to the population of organisms C and D.
STEP 3
Communicate to the examiner using the correct scientific keywords.
First, explain why the population of C decreased. (represented by the orange arrow)
- With the addition of organism E, there are more predators feeding on C. The population of C decreases.
Next, explain why the population of D will decrease. (Represented by the green arrow)
- Organisms D and E are competing to feed on C. Some of D will die of starvation as there is less food for D. Hence, the population of D decreases.
FINALLY, put your answer together
Question: A new population of organism E is introduced to the community. Organism E feeds on C. How will the population of Organism D be affected? Explain your answer.
Answer:
The population of D will decrease.
With the addition of organisms E, there are more predators feeding on C. The population of C decreased. Organisms D and E are competing to feed on C. Some of D will die of starvation as there is less food for D. Hence, the population of D decreased.
Is this correct?
You may have this analysis.
There are more organisms E feeding on C. The population of C decreases.
There are fewer organisms C feeding on B. The population of B increases.
Since the population of C decreases and the population of B increases, D has enough food and there is no change to its population.
That answer is too complicated and it has problems…
We don’t know these:
how much does the population of B increase?
And how much does the population of C decrease?
They will affect the population of D.
What should we do then?
Since the question is asking for the population of organism D, we should use a much easier explanation.
And that is to focus on the direct food relationships of organisms C with D and E!
Learning point
Focus on the direct food relationships between organisms as much as possible.
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Click on the link below to revise another must-know food chain and food web question
>>> https://scienceshifu.com/food-chains-and-food-web-changes-in-the-population-of-living-things/
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Andy Ling
Guiding your child to be the master of science concepts
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