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The Life of Plants - Terrestrial and Aquatic Adaptations

Grade 4CBSE

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

🔑Concepts

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Terrestrial Plants: These are plants that grow on land. They are classified based on their habitat: Mountains (conical shape, needle-like leaves), Deserts (fleshy stems to store H2OH_2O, leaves modified into spines), Plains (deciduous or evergreen trees), and Marshy areas (breathing roots or pneumatophores).

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Desert Adaptations: To prevent loss of H2OH_2O through transpiration, desert plants like the Cactus have spines instead of leaves. Their green, fleshy stems perform photosynthesis and store water.

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Aquatic Plants: These grow in water and are divided into three types: Floating (e.g., Duckweed), Fixed (e.g., Lotus), and Underwater/Submerged (e.g., Hydrilla).

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Fixed Aquatic Plants: Plants like the Lotus have long, hollow, and light stems to reach the surface of the water. Their leaves are broad and have a waxy coating to prevent rotting in H2OH_2O.

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Underwater Plants: These plants, such as Hydrilla and Tape Grass, have narrow, ribbon-like leaves with no stomata. They breathe in CO2CO_2 dissolved in water through their body surface.

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Photosynthesis: The process by which plants use Sunlight, Chlorophyll, CO2CO_2, and H2OH_2O to prepare food. The reaction releases O2O_2 as a byproduct.

📐Formulae

6CO2+6H2O→ChlorophyllSunlightC6H12O6+6O26CO_2 + 6H_2O \xrightarrow[Chlorophyll]{Sunlight} C_6H_{12}O_6 + 6O_2

Carbon Dioxide+Water→Glucose (Sugar)+Oxygen\text{Carbon Dioxide} + \text{Water} \rightarrow \text{Glucose (Sugar)} + \text{Oxygen}

💡Examples

Problem 1:

Why do plants in marshy areas have roots that grow above the soil?

Solution:

Marshy areas have soil that is very sticky and clayey, which contains a lot of H2OH_2O but very little air. Therefore, the roots grow upwards out of the soil to breathe air.

Explanation:

These specialized roots are called breathing roots or pneumatophores, which help the plant obtain oxygen that is unavailable in the waterlogged soil.

Problem 2:

Identify the adaptation that helps a Lotus leaf float and stay dry.

Solution:

The Lotus leaf is broad and has a waxy coating on its surface, which makes it waterproof and prevents H2OH_2O from blocking the stomata.

Explanation:

The waxy layer ensures that water droplets roll off, preventing the leaf from rotting and allowing the exchange of gases like CO2CO_2 and O2O_2 through the stomata located on the upper surface.

Problem 3:

How does a Cactus survive in the desert where there is a scarcity of H2OH_2O?

Solution:

The Cactus has three main adaptations: 1. Leaves are reduced to spines to prevent H2OH_2O loss. 2. Photosynthesis happens in the green, fleshy stem. 3. The stem stores H2OH_2O.

Explanation:

By reducing the surface area of leaves to spines, the rate of transpiration is minimized, conserving the limited H2OH_2O available in the arid environment.