Which term describes an external skeleton found in arthropods and some mollusks?

Which term describes an external skeleton found in arthropods and some mollusks?

• A. Gill Membranes
• B. Exoskeleton
• C. Echolocation
• D. Gastropoda

Answer: (B)

An exoskeleton is a hard outer covering that provides support, protection, and muscle attachment points. In arthropods this skeleton is typically made of chitin and must be shed as the animal grows, a process called molting. Some mollusks also have external shells made of calcium carbonate that serve a similar protective role, though their structure differs from the arthropod exoskeleton. This outer framework is what the term describes. The other options relate to different ideas: gill membranes are for gas exchange, echolocation is a sensing system, and Gastropoda refers to a mollusk group rather than the external skeleton concept.

An exoskeleton is a hard outer covering that provides support, protection, and muscle attachment points. In arthropods this skeleton is typically made of chitin and must be shed as the animal grows, a process called molting. Some mollusks also have external shells made of calcium carbonate that serve a similar protective role, though their structure differs from the arthropod exoskeleton. This outer framework is what the term describes. The other options relate to different ideas: gill membranes are for gas exchange, echolocation is a sensing system, and Gastropoda refers to a mollusk group rather than the external skeleton concept.