NCERT Class 6 Science — Chapter 4: The living organisms - characteristics and habitats

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Why do aquatic plants typically possess a reduced or poorly developed root system?

Official previous-year question

Verified 1 Aug 2026.

Options

AThe aquatic substrate is too dense for root penetration.
BTo minimize plant weight for better buoyancy.
CWater and nutrients are directly available from the surroundings.
DTo prevent the plant from being anchored in strong currents.

Did you get this right?

Solution

The correct option is

Water and nutrients are directly available from the surroundings.

Explanation

Aquatic plants, or hydrophytes, exhibit specific morphological and anatomical adaptations to survive in water-rich environments. Unlike terrestrial plants (mesophytes or xerophytes), their structural development is governed by the abundance of water and the need for buoyancy rather than water conservation or absorption from deep soil.

Detailed Analysis:

Water and nutrients are directly available from the surroundings. is Correct: In terrestrial plants, the primary function of the root system is to absorb water and mineral nutrients from the soil. However, in aquatic plants, the entire plant body is typically in direct contact with water. Consequently, water and dissolved minerals can be absorbed directly through the general body surface (epidermis). This renders an extensive root system functionally redundant for absorption, leading to a reduced or poorly developed root system.
The aquatic substrate is too dense for root penetration. is Incorrect: The density of the aquatic substrate (mud or sand) is not the primary factor limiting root growth. Many aquatic plants grow in soft mud where penetration would be easy, yet they still possess reduced roots.
To minimize plant weight for better buoyancy. is Incorrect: While buoyancy is crucial for aquatic plants, it is primarily achieved through the development of aerenchyma (specialized parenchyma tissue with large air spaces), not merely by reducing the root system. Weight reduction is a secondary outcome, not the primary evolutionary driver for root reduction.
To prevent the plant from being anchored in strong currents. is Incorrect: Roots in aquatic plants, when present, often serve the specific function of anchorage to keep the plant fixed in the substrate. They are not reduced to prevent anchoring; rather, they are reduced because their absorptive role is diminished.

Key Takeaway:
In hydrophytes, the root system is poorly developed because water and mineral absorption occurs directly through the plant surface, making specialized absorptive roots unnecessary.

Your note

More from Chapter 4: The living organisms - characteristics and habitats

With reference to the concept of 'adaptation' in living organisms, consider the following statements: 1. It refers to the small changes that take place in the body of a single organism over a short period to overcome changes in the surroundings. 2. It involves specific features or habits that enable an organism to live naturally in a place. 3. It is a rapid process that occurs within a few days. Which of the statements given above is/are correct?

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What does the term 'acclimatisation' refer to in a biological context?

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Consider the following statements regarding the components of a habitat: 1. The organisms, both plants and animals, living in a habitat constitute its biotic components. 2. Rocks and soil are considered biotic components of a habitat. 3. Sunlight and heat are classified as abiotic components of a habitat. Which of the statements given above is/are correct?

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With reference to the germination of seeds, consider the following statements based on abiotic factors: 1. Seeds can germinate in the complete absence of air and water. 2. Light and heat are abiotic factors that influence the growth of plants. 3. Abiotic factors are important for all living organisms. Which of the statements given above are correct?

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Consider the following specific features of a camel that help it survive in desert conditions: 1. They excrete a small amount of urine to conserve water. 2. They sweat profusely to keep their bodies cool. 3. They have very short legs to keep their bodies close to the ground. Which of the statements given above is/are correct?

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The correct option is

Water and nutrients are directly available from the surroundings.

Explanation

Detailed Analysis:

Water and nutrients are directly available from the surroundings. is Correct: In terrestrial plants, the primary function of the root system is to absorb water and mineral nutrients from the soil. However, in aquatic plants, the entire plant body is typically in direct contact with water. Consequently, water and dissolved minerals can be absorbed directly through the general body surface (epidermis). This renders an extensive root system functionally redundant for absorption, leading to a reduced or poorly developed root system.
The aquatic substrate is too dense for root penetration. is Incorrect: The density of the aquatic substrate (mud or sand) is not the primary factor limiting root growth. Many aquatic plants grow in soft mud where penetration would be easy, yet they still possess reduced roots.
To minimize plant weight for better buoyancy. is Incorrect: While buoyancy is crucial for aquatic plants, it is primarily achieved through the development of aerenchyma (specialized parenchyma tissue with large air spaces), not merely by reducing the root system. Weight reduction is a secondary outcome, not the primary evolutionary driver for root reduction.
To prevent the plant from being anchored in strong currents. is Incorrect: Roots in aquatic plants, when present, often serve the specific function of anchorage to keep the plant fixed in the substrate. They are not reduced to prevent anchoring; rather, they are reduced because their absorptive role is diminished.

Key Takeaway:
In hydrophytes, the root system is poorly developed because water and mineral absorption occurs directly through the plant surface, making specialized absorptive roots unnecessary.