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Some Unique Places - Coral Reefs and Mangrove Forests

Grade 5CBSE

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

🔑Concepts

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Coral reefs are diverse underwater ecosystems formed by colonies of tiny animals called coral polyps, which secrete Calcium Carbonate (CaCO3CaCO_3) to form a hard skeleton.

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Corals have a symbiotic relationship with microscopic algae called Zooxanthellae. The algae provide food via photosynthesis, while the coral provides shelter and nutrients.

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Coral reefs are often referred to as the 'Rainforests of the Sea' because they support approximately 25%25\% of all marine species.

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Mangrove forests are unique coastal ecosystems consisting of salt-tolerant trees and shrubs, often found in tropical and subtropical intertidal zones.

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Mangroves have specialized roots called 'Pneumatophores' or breathing roots that grow upwards out of the waterlogged soil to absorb oxygen (O2O_2) from the air.

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Adaptations in mangroves include 'Prop Roots' and 'Stilt Roots' which help the trees stay stable in soft, shifting mud and withstand strong tidal currents.

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Mangroves act as a natural barrier, protecting coastlines from erosion, storm surges, and tsunamis.

📐Formulae

CaCO3 (Calcium Carbonate - the building block of coral reefs)CaCO_3 \text{ (Calcium Carbonate - the building block of coral reefs)}

6CO2+6H2O+light→C6H12O6+6O2 (Photosynthesis process within Zooxanthellae)6CO_2 + 6H_2O + \text{light} \rightarrow C_6H_{12}O_6 + 6O_2 \text{ (Photosynthesis process within Zooxanthellae)}

💡Examples

Problem 1:

A specific type of branching coral grows at a rate of 12 cm12 \text{ cm} per year. If a reef segment is currently 245 cm245 \text{ cm} tall, what will its height be after 33 years of growth?

Solution:

245+(12×3)=245+36=281 cm245 + (12 \times 3) = 245 + 36 = 281 \text{ cm}

Explanation:

To find the new height, we first calculate the growth over 3 years (12×3=3612 \times 3 = 36). Then we add this to the initial height using vertical addition: 245+36281\begin{array}{r} 245 \\ + 36 \\ \hline 281 \end{array} The reef will be 281 cm281 \text{ cm} tall.

Problem 2:

Why do mangrove trees have 'breathing roots' while most land plants do not?

Solution:

Mangroves grow in saline, waterlogged soil which is deficient in oxygen (O2O_2).

Explanation:

Normal soil has air pockets, but in mangrove swamps, the soil is covered by water. To survive, mangroves evolve pneumatophores that rise above the water level to capture air for respiration.

Problem 3:

If a coastal area has 500500 hectares of mangrove forest and 145145 hectares are destroyed by a storm, how many hectares of forest remain to protect the coast?

Solution:

500−145=355 hectares500 - 145 = 355 \text{ hectares}

Explanation:

Using vertical subtraction to find the remaining area: 500−145355\begin{array}{r} 500 \\ - 145 \\ \hline 355 \end{array} There are 355 hectares355 \text{ hectares} of mangrove forest remaining.