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Animal Life - Food Chains

Grade 3ICSE

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

🔑Concepts

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All living things need energy to grow and survive, which they get from food.

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The Sun is the ultimate source of energy for all living organisms on Earth.

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Producers: Green plants are called producers because they prepare their own food using sunlight, water, and carbon dioxide (CO2CO_2) through a process called photosynthesis.

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Consumers: Animals cannot make their own food and depend on plants or other animals. They are classified into: Herbivores (plant-eaters), Carnivores (flesh-eaters), and Omnivores (eat both).

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Food Chain: A sequence that shows how energy passes from one living thing to another. It always starts with a producer (plant).

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The arrow (ightarrow ightarrow) in a food chain represents the flow of energy from the organism being eaten to the organism that eats it.

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Decomposers: Organisms like fungi and bacteria that break down dead plants and animals, returning nutrients to the soil.

📐Formulae

Sunlight+Water+CO2→ChlorophyllFood (Sugar)+O2\text{Sunlight} + \text{Water} + CO_2 \xrightarrow{\text{Chlorophyll}} \text{Food (Sugar)} + O_2

Producer→Herbivore→Carnivore\text{Producer} \rightarrow \text{Herbivore} \rightarrow \text{Carnivore}

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

💡Examples

Problem 1:

Arrange the following organisms to form a correct terrestrial food chain: Eagle, Grass, Snake, Frog, Grasshopper.

Solution:

Grass→Grasshopper→Frog→Snake→EagleGrass \rightarrow Grasshopper \rightarrow Frog \rightarrow Snake \rightarrow Eagle

Explanation:

In this chain, Grass is the producer. The Grasshopper (herbivore) eats the grass, the Frog (carnivore) eats the grasshopper, the Snake eats the frog, and the Eagle is the top predator.

Problem 2:

Identify the producer and the primary consumer in the following chain: Pond Weeds→Small Fish→CranePond \: Weeds \rightarrow Small \: Fish \rightarrow Crane

Solution:

Producer: Pond WeedsPond \: Weeds; Primary Consumer: Small FishSmall \: Fish.

Explanation:

Pond weeds are plants that produce food using sunlight, making them producers. The small fish is the first animal to eat the producer, making it the primary consumer.

Problem 3:

What happens to the energy flow if all the plants (producers) in an ecosystem are removed?

Solution:

The energy flow stops and the food chain collapses.

Explanation:

Since all animals eventually depend on plants for food (either directly or indirectly), the removal of producers means there is no C6H12O6C_6H_{12}O_6 (glucose/energy) being created to support the consumers.