With reference to aquatic animals, consider the following statements: 1. All sea animals have a streamlined shape to move easily in water. 2. Squids and octopuses make their body shapes streamlined when they move in water. 3. Gills are the primary respiratory organs in most fish. Which of the statements given above are correct?

The correct option is (c) 2 and 3 only. Explanation Aquatic animals exhibit various adaptations to survive in water, including body shape modifications for movement and specialized organs for respiration. While streamlining is a common adaptation to reduce friction, it is not universal among all aquatic species. Statement-wise Analysis: - Statement 1 is Incorrect: Not all sea animals possess a streamlined shape. Organisms such as squids and octopuses, which typically inhabit deeper ocean levels near the seabed, do not naturally have a streamlined body shape while at rest. Other bottom-dwellers like starfish also lack this shape. - Statement 2 is Correct: Although squids and octopuses are not permanently streamlined, they possess the physiological ability to alter their body shape. When they need to move through the water, they make their bodies streamlined to reduce resistance and swim efficiently. - Statement 3 is Correct: Gills are the primary respiratory organs in most fish. They are specialized projections of the skin that allow fish to extract oxygen dissolved in water. Aquatic mammals like whales and dolphins do not possess gills; they breathe air through blowholes or nostrils. Key Takeaway: While a streamlined body is a prevalent adaptation for reducing water resistance, some deep-sea animals like squids adopt this shape only during movement. Gills are the standard respiratory organ for fish, whereas aquatic mammals utilize lungs.

With reference to aquatic animals, consider… - NCERT Class 6 Science MCQ

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

mcqmedium

With reference to aquatic animals, consider the following statements:

All sea animals have a streamlined shape to move easily in water.
Squids and octopuses make their body shapes streamlined when they move in water.
Gills are the primary respiratory organs in most fish.

Which of the statements given above are correct?

NCERT textbook question

From NCERT Science - class 6 · Page 85

Options

A1 and 2 only
B2 only
C2 and 3 only
D1, 2 and 3

Did you get this right?

Solution

The correct option is (c) 2 and 3 only.

Explanation

Aquatic animals exhibit various adaptations to survive in water, including body shape modifications for movement and specialized organs for respiration. While streamlining is a common adaptation to reduce friction, it is not universal among all aquatic species.

Statement-wise Analysis:

Statement 1 is Incorrect: Not all sea animals possess a streamlined shape. Organisms such as squids and octopuses, which typically inhabit deeper ocean levels near the seabed, do not naturally have a streamlined body shape while at rest. Other bottom-dwellers like starfish also lack this shape.
Statement 2 is Correct: Although squids and octopuses are not permanently streamlined, they possess the physiological ability to alter their body shape. When they need to move through the water, they make their bodies streamlined to reduce resistance and swim efficiently.
Statement 3 is Correct: Gills are the primary respiratory organs in most fish. They are specialized projections of the skin that allow fish to extract oxygen dissolved in water. Aquatic mammals like whales and dolphins do not possess gills; they breathe air through blowholes or nostrils.

Key Takeaway: While a streamlined body is a prevalent adaptation for reducing water resistance, some deep-sea animals like squids adopt this shape only during movement. Gills are the standard respiratory organ for fish, whereas aquatic mammals utilize lungs.

Your note

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

Consider the following statements regarding the 'prey-predator' relationship in grasslands: 1. In a grassland ecosystem, the lion is considered a primary consumer. 2. A deer is a prey. 3. Prey animals usually have eyes on the side of their heads. Which of the statements given above are correct?

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With reference to excretion in plants, consider the following statements: 1. Plants do not excrete waste products like animals do. 2. Some plants store waste products within their parts in a way that does not harm the plant. 3. Plants cannot remove waste products through secretions. Which of the statements given above is/are correct?

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With reference to desert plants, consider the following statements: 1. Leaves are either absent, very small, or modified into spines. 2. The stem is generally thin and porous to allow water loss. 3. Photosynthesis in some desert plants is carried out by the green stem. Which of the statements given above is/are correct?

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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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Which phenomenon demonstrates that stored seeds continue to undergo respiration?

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