Question

Assertion: Cnidoblasts are present on the tentacles and the body of the cnidarians.
Reason: Cnidoblasts are used for the anchorage, defence and capture of the prey.
A) Both assertion and reason are correct and the reason is the correct explanation of the assertion.
B) Both assertion and reason are correct and the reason is not the correct explanation of the assertion.
C) Assertion is correct but the reason is incorrect.
D) Both assertion and reason are incorrect.

Answer 1

Hint: Cnidarians are a group of animals that belong to the phylum Coelenterata. The phylum Coelenterata is also known as Cnidaria. They contain several cnidoblast cells in their body.

Complete answer: Cnidarians are the diploblastic animals that are radially symmetrical in nature as their body can be equally divided into two halves in any plane. They are tentacle bearing organisms. They are the finger-like structures encircling the mouth. These tentacles help in the collection of food in these organisms. The presence of cnidoblast cells is the characteristic feature of these organisms. They are offensive and defensive stinging cells. Cnidoblast cells have a poison-filled capsule called a nematocyst. It also contains a string and a trigger-like structure called cnidocil. They are the modifications of the epidermal cells of these organisms. Cnidoblast cells are seen in tentacles and they help in the anchorage of these cells to the surfaces they live on. They are also used for defensive purposes and to capture prey. The presence of a Coelenteron is a special feature of these organisms. It is an internal digestive cavity that opens out only through the mouth. It is also called a gastrovascular cavity. Cnidarians constitute a group made up of more than 9,000 living species. Mostly marine animals, they include the corals, hydras, jellyfish, sea pens, sea whips, and sea fans.
Hence the correct answer is option B.

Note: Polymorphism is the phenomenon in which the same group of organisms have different morphological features. Cnidarians show polymorphism. Division of labour is seen by the occurrence of different types of individuals in a species based on their function in the society or a colony.