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.

Scienceshifu - P6 food web - Predict the populations of other organisms

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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Talk again soon!

Andy Ling

Guiding your child to be the master of science concepts

 

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