Problem 105 - Objective Biology for NEET

Question

Exoskeleton of Arthropods are chitinous and it sheds at interval for the growth and development process known as (a) Autotomy (b) Metamerism (c) Ecdysis (moulting) (d) Aestivation

Step-by-Step Solution

Answer

The correct answer is (c) Ecdysis (moulting).

Step 1: Understanding The Terms

Autotomy is the shedding or discarding of body parts, often used as a defense mechanism. Metamerism is a segmentation of the body, common in worms and arthropods. Ecdysis (moulting) is the process by which arthropods shed their exoskeletons for growth or development. Aestivation, or estivation, is a state of animal dormancy, similar to hibernation, characterized by inactivity during dry periods.

Step 2: Connecting The Term To Arthropods' Exoskeleton

Arthropods have a chitinous exoskeleton that they shed at intervals for the growth and development process. Based on the definitions provided, the process which best relates to the shedding of the exoskeleton of Arthropods for their growth is Ecdysis (moulting).

Step 3: Confirming The Answer

After analysing each term, it can be concluded that the correct answer is Ecdysis (moulting), as this process specifically involves the shedding of the exoskeleton of Arthropods.

Key Concepts

Exoskeleton

An exoskeleton is a hard outer structure that provides support and protection to an organism's body. In the world of arthropods, which includes insects, spiders, and crustaceans, the exoskeleton acts like a suit of armor. It covers the entire body, offering a shield against predators and environmental dangers.

This tough and rigid layer is not just for protection; it serves as an attachment point for muscles, quite like the human skeleton does internally. This setup allows for movement and flexibility. However, the key difference between an exoskeleton and endoskeleton is that the exoskeleton is outside the body.

• Provides physical protection
• Supports an organism’s form and structure
• Acts as a barrier to pathogens

Because the exoskeleton is rigid, it doesn't grow with the organism. This necessity leads to a fascinating process known as ecdysis, which lets arthropods grow bigger by shedding their old exoskeleton and forming a new one.

Chitin

Chitin is a crucial material that makes up the exoskeleton of arthropods. It is a long-chain polymer that is also found in the walls of fungi and the scales of fish. In the case of arthropods, chitin provides durability and flexibility to the exoskeleton.

One of chitin’s remarkable properties is that it is very lightweight, which is beneficial for arthropods as they can move swiftly without being weighed down.

• Composed of complex carbohydrates
• Enables both strength and flexibility
• Found in other organisms, such as fungi

Chitin does not exist alone; it is usually entwined with proteins and sometimes calcium carbonate. This combination increases the strength and toughness of the exoskeleton. In arthropods, the sturdy nature of chitin is what makes their outer shells both strong and resilient.

Ecdysis

Ecdysis is the biological process where arthropods shed their exoskeletons to grow a new one. This is necessary since the exoskeleton doesn't expand or grow with the organism. As an arthropod grows, its exoskeleton becomes too tight and must be shed in a process called molting.

Ecdysis is a critical phase in an arthropod's life cycle. It involves several stages, including the release of enzymes that break down the old exoskeleton, making it easier to detach.

• Allows for growth
• Occurs regularly throughout an arthropod's life
• Involves biochemical processes to break down the old exoskeleton

After shedding, the new exoskeleton is initially soft and vulnerable. This is why many arthropods seek shelter during this time. Over the next few hours or days, the new exoskeleton hardens, and the arthropod can resume normal activity with more room to grow.