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Staying Alive - Food Chains

Grade 3Cambridge (IGCSE)

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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A food chain always begins with a producer. For example, in a garden: Grass→Grasshopper→Frog→Snake\text{Grass} \rightarrow \text{Grasshopper} \rightarrow \text{Frog} \rightarrow \text{Snake} In this chain, the grass captures solar energy, the grasshopper gets energy by eating the grass, and so on.

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Energy flow is represented by arrows. If we look at the relationship A→BA \rightarrow B, it means organism AA provides energy to organism BB. Mathematically, we can think of the energy transfer as a sequence: ESun→EProducer→EConsumer 1→EConsumer 2E_{\text{Sun}} \rightarrow E_{\text{Producer}} \rightarrow E_{\text{Consumer 1}} \rightarrow E_{\text{Consumer 2}}

📐Formulae

Sunlight→EnergyProducer→EnergyConsumer\text{Sunlight} \xrightarrow{\text{Energy}} \text{Producer} \xrightarrow{\text{Energy}} \text{Consumer}

Carbon Dioxide+Water→Sunlight/ChlorophyllFood (Glucose)+Oxygen\text{Carbon Dioxide} + \text{Water} \xrightarrow{\text{Sunlight/Chlorophyll}} \text{Food (Glucose)} + \text{Oxygen}

Producer→Primary Consumer→Secondary Consumer→Tertiary Consumer\text{Producer} \rightarrow \text{Primary Consumer} \rightarrow \text{Secondary Consumer} \rightarrow \text{Tertiary Consumer}

💡Examples

Problem 1:

Identify the roles of each organism in the following food chain: Corn→Mouse→Owl\text{Corn} \rightarrow \text{Mouse} \rightarrow \text{Owl}

Solution:

  1. Corn: Producer
  2. Mouse: Primary Consumer (Herbivore and Prey)
  3. Owl: Secondary Consumer (Carnivore and Predator)

Explanation:

The Corn uses sunlight to make food. The Mouse eats the corn to get energy, making it the primary consumer. The Owl eats the mouse, making it the secondary consumer and the predator in this relationship.

Problem 2:

If a disease kills all the frogs in a pond food chain: Algae→Mayfly Larva→Frog→Heron\text{Algae} \rightarrow \text{Mayfly Larva} \rightarrow \text{Frog} \rightarrow \text{Heron}, what will happen to the population of Mayfly Larvae?

Solution:

The population of Mayfly Larvae will increase.

Explanation:

Since the Frogs (the predator of the Mayfly Larvae) are gone, fewer Mayfly Larvae will be eaten. This causes their population count (nn) to rise: nlarvae↑n_{\text{larvae}} \uparrow because the death rate from predation decreases.