The hemocoel is the main body cavity of arthropods involved in circulation. Although arthropods are coelomates developmentally, the hemocoel dominates in adults. This MCQ belongs to the Arthropoda topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.
Many molluscs and annelids have a trochophore larva, supporting evolutionary links among lophotrochozoan animals. It is a small ciliated larval stage. This MCQ belongs to the Mollusca topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.
The clitellum is a glandular region in earthworms and some other annelids. It secretes mucus and forms the cocoon during reproduction. This MCQ belongs to the Annelida topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.
Insects have three pairs of legs attached to the thorax, along with a body divided into head, thorax, and abdomen. This separates them from arachnids and crustaceans. This MCQ belongs to the Insecta topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.
Mandibles are jaw-like mouthparts in many arthropods, especially insects and crustaceans. They are modified appendages used for biting, chewing, or handling food. This MCQ belongs to the Arthropoda topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.
Most molluscs have an open circulatory system in which hemolymph moves through a hemocoel. Cephalopods are the major exception with a closed circulatory system. This MCQ belongs to the Mollusca topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.
Many marine annelids have a trochophore larva. This larval type is important in comparing annelids with molluscs among lophotrochozoans. This MCQ belongs to the Annelida topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.
Arachnids, including spiders and scorpions, usually have four pairs of walking legs and no antennae. Their body is often divided into cephalothorax and abdomen. This MCQ belongs to the Arachnida topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.
A biramous appendage has two branches and is typical of many crustaceans. Insects and myriapods generally have uniramous appendages. This MCQ belongs to the Arthropoda topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.
Molluscan gills are called ctenidia. They are usually located in the mantle cavity and may also assist in feeding in bivalves. This MCQ belongs to the Mollusca topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.
Correct Answer: D. cerebral ganglia with ventral nerve cord
Explanation:
Annelids have a more centralized nervous system than cnidarians, including cerebral ganglia and a ventral nerve cord with segmental ganglia. This MCQ belongs to the Annelida topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.
Crustaceans typically have two pairs of antennae and many possess biramous appendages. They are mostly aquatic arthropods, although some groups are terrestrial. This MCQ belongs to the Crustacea topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.
