Zoology MCQs for NEET — Practice Questions with Answers

In Porifera, the skeleton is made up of both spicules and spongin. Spicules are small, spike-like structures made of calcium carbonate or silica, while spongin is a fibrous protein. Together, they provide structural support to the sponge body.

Physalia, commonly known as the Portuguese man o' war, is a marine hydrozoan. It is not a single animal but a colonial organism made up of specialized individual animals (zooids) working together.

To match the items correctly, we need to associate the organisms with their phyla. Spongilla is a freshwater sponge that belongs to Porifera. Adamsia, also known as sea anemone, belongs to Cnidaria. Liver fluke is a parasitic flatworm that belongs to Platyhelminthes. Nereis is a type of polychaete worm that belongs to Annelida. Thus, the correct matching is: p - (i), q - (iv), r - (ii), s - (iii).

Cnidoblasts are specialized cells found in Cnidarians that contain stinging organelles called nematocysts. They play a role in anchorage, defense against predators, and capturing prey. Thus, all of the given options (anchorage, defense, capture) are correct.

The gastro-vascular cavity is a central digestive compartment found in Cnidarians like Hydra. It serves both digestive and circulatory functions. Earthworms, liver flukes, and Ascaris do not possess a gastro-vascular cavity. Therefore, the correct answer is Hydra.

Pleurobrachia, a genus of comb jellies, possesses 8 external rows of ciliated comb plates, which they use for locomotion. These comb plates are one of the distinguishing features of ctenophores.

Flame cells are specialized excretory cells found in platyhelminthes (flatworms). They function in osmoregulation and excretion, helping to remove waste materials from the organism's body.

The pseudocoelomate among the given options is Aschelminthes. Pseudocoelomates are animals that have a body cavity that is not entirely lined by mesoderm. Aschelminthes, also known as nematodes or roundworms, possess this type of body cavity. Porifera, Annelida, and Mollusca do not have a pseudocoelom; Porifera are characterized by having no true body cavity, Annelida are coelomates with a true coelom, and Mollusca are also coelomates.