Problem 120 - Objective Biology for NEET

Question

A. A soft and spongy layer of skin forms a _ (i)_over the visceral hump. B. A _(ii)_cavity containing_(iii)_ like gills. C. The anterior head region has sensory (iv)_. Fill in the blanks in the above respective places about mollusca. (a) Mantle, Mantle, Comb, Papilla (b) Mantle, Mesoglea, Feather, Papilla (c) Mantle, Mantle, Feather, Tentacles (d) Mantle, Mantle, Comb, Tentacles

Step-by-Step Solution

Answer

The answer is (c) Mantle, Mantle, Feather, Tentacles.

Step 1: Identify Characteristics of Mollusca

To start off, it will be beneficial to understand the characteristics of mollusca. As per the information given in the question, mollusca have a soft and spongy mantle layer and a mantle cavity which contains feather-like gills. Its anterior head region has sensory organs. Verify these features with the known characteristics of mollusca for confirmation.

Step 2: Match with Given Options

Having identified the specifics of mollusca, now match these characteristics with the provided options. The mantle fits for (i), another mantle for (ii), feather-like gills for (iii) and the sensory organ could be tentacles for (iv).

Step 3: Select the Correct Option

After going through all the options with the decided characteristics of mollusca, option (c) seems to perfectly fill the blanks - (c) Mantle, Mantle, Feather, Tentacles. Therefore, the answer should be option (c).

Key Concepts

Mantle

The mantle is an essential part of a mollusk's anatomy. It is a soft and spongy layer of skin that acts as a protective covering. This layer is crucial because it forms a cloak over the visceral hump, safeguarding the internal organs and structures.

The mantle not only protects but also plays a role in secretions. It is responsible for secreting the substance that forms shells in many mollusks.

Key functions of the mantle include:

• Protection: Acts as a shield for internal organs.
• Secretion: Produces the shell material in shelled mollusks.

The mantle is an integral feature that distinguishes mollusks from other invertebrates.

Sensory Organs

Mollusks have a variety of sensory organs, which are mainly located in the anterior head region. These sensory organs help the animal interact with its environment, aiding in protection and survival.

Some mollusks have tentacles, which are especially useful as sensory organs. These tentacles can detect changes in the environment, such as movement, pressure, and chemicals in the water.

Important aspects of mollusk sensory organs include:

• Detection: Tentacles help sense environmental changes.
• Adaptation: Sensory organs are crucial for survival in varied environments.

These adaptations allow mollusks to thrive in diverse habitats.

Gills

In mollusks, gills are essential for respiration and can be found within the mantle cavity. Often described as feather-like structures, gills are involved in gas exchange, allowing the mollusk to breathe.

The gills are efficient because they have a large surface area, which enhances their ability to exchange gases with the surrounding water.

Key features of mollusk gills:

• Respiration: Essential for breathing and gas exchange.
• Structure: Feather-like to maximize gas exchange efficiency.

The gills' strategic location inside the mantle cavity helps protect them from damage.

Visceral Hump

The visceral hump in mollusks contains the bulk of the animal's internal organs. This critical part of the body houses organs such as the digestive, excretory, and reproductive systems.

The viscera or inner organs are usually protected by the mantle. The visceral hump's position underneath the mantle ensures these sensitive organs are shielded from external harm.

The visceral hump encompasses:

• Organ Protection: Ensures safety for essential internal organs.
• Complex Systems: Houses multiple bodily systems, including digestion and reproduction.

The visceral hump plays a vital role in maintaining the normal physiological processes of the mollusk.