Coelenterata, Platyhelminthes and Aschelminthes Practice Questions
19 free Coelenterata, Platyhelminthes and Aschelminthes practice questions for the NCERT Biology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
The name Cnidaria is derived from specialized cells called cnidoblasts, which contain stinging capsules known as:
- A Choanocytes
- B Nematocysts
- C Statocysts
- D Flame cells
Correct answer: Nematocysts
Cnidoblasts or cnidocytes contain the stinging capsules or nematocysts, which are present on the tentacles and the body. These are used for anchorage, defense, and for the capture of prey.
Which of the following body forms in Cnidarians is sessile and cylindrical, such as in Hydra and Adamsia?
- A Medusa
- B Polyp
- C Planula
- D Trochophore
Correct answer: Polyp
Cnidarians exhibit two basic body forms: polyp and medusa. The polyp is a sessile and cylindrical form, whereas the medusa is umbrella-shaped and free-swimming like Jellyfish.
Metagenesis (alternation of generation) is observed in which of the following cnidarians?
- A Hydra
- B Adamsia
- C Obelia
- D Aurelia
Correct answer: Obelia
In Obelia, polyps produce medusae asexually and medusae form the polyps sexually. This phenomenon is known as metagenesis.
The central gastro-vascular cavity in Cnidarians opens through a single opening on the:
- A Osculum
- B Peristome
- C Radula
- D Hypostome
Correct answer: Hypostome
Cnidarians have a central gastro-vascular cavity with a single opening, the mouth, located on the hypostome. This represents an incomplete digestive system.
Which of the following is commonly known as 'Portuguese man-of-war'?
- A Pennatula
- B Gorgonia
- C Meandrina
- D Physalia
Correct answer: Physalia
Physalia is known as the Portuguese man-of-war. Other examples include Pennatula (Sea-pen), Gorgonia (Sea-fan), and Meandrina (Brain coral).
Platyhelminthes are called 'flatworms' because they have a:
- A Cylindrical and elongated body
- B Metamerically segmented body
- C Laterally flattened body
- D Dorso-ventrally flattened body
Correct answer: Dorso-ventrally flattened body
Phylum Platyhelminthes includes organisms that have a dorso-ventrally flattened body, hence they are called flatworms. Most of them are endoparasites found in animals including human beings.
Specialized cells called 'flame cells' in Platyhelminthes help in:
- A Digestion and food absorption
- B Respiration and circulation
- C Osmoregulation and excretion
- D Bioluminescence and defense
Correct answer: Osmoregulation and excretion
Flame cells are specialized excretory structures in flatworms. They facilitate osmoregulation and the removal of nitrogenous wastes from the body.
Which of the following flatworms possesses a high regeneration capacity?
- A Taenia
- B Fasciola
- C Planaria
- D Schistosoma
Correct answer: Planaria
Planaria is a free-living flatworm known for its remarkable ability to regenerate a complete organism from a small fragment of its body.
Flatworms are characterized by which type of body cavity?
- A Coelomate
- B Pseudocoelomate
- C Acoelomate
- D Haemocoelomate
Correct answer: Acoelomate
Flatworms are acoelomate, meaning they lack a body cavity between the gut wall and the outer body wall. They are also triploblastic and show bilateral symmetry.
In parasitic flatworms like Taenia, which structures are present for attachment to the host?
- A Hooks and suckers
- B Tentacles and cnidoblasts
- C Parapodia and setae
- D Pseudopodia
Correct answer: Hooks and suckers
Parasitic forms of Platyhelminthes possess hooks and suckers for attachment to the host's intestinal wall. Some also absorb nutrients directly through their body surface.
Aschelminthes are commonly called 'roundworms' because:
- A The body is circular in cross-section
- B Their body is triangular in cross-section
- C They always live in round colonies
- D Their eggs are perfectly spherical
Correct answer: The body is circular in cross-section
The body of Aschelminthes is circular in cross-section, which is why they are called roundworms. They can be free-living, aquatic, terrestrial, or parasitic.
Which phylum is the first to exhibit a 'pseudocoelom'?
- A Porifera
- B Cnidaria
- C Platyhelminthes
- D Aschelminthes
Correct answer: Aschelminthes
Aschelminthes are pseudocoelomate, meaning the body cavity is not lined by mesoderm; instead, the mesoderm is present as scattered pouches between the ectoderm and endoderm.
A well-developed muscular pharynx is a characteristic feature of the digestive system in:
- A Hydra
- B Taenia
- C Ascaris
- D Fasciola
Correct answer: Ascaris
Aschelminthes, like Ascaris, possess a complete alimentary canal with a well-developed muscular pharynx. This allows for more efficient ingestion of food compared to flatworms.
Which of the following is the 'Filaria worm' that causes elephantiasis?
- A Wuchereria
- B Ascaris
- C Ancylostoma
- D Enterobius
Correct answer: Wuchereria
Wuchereria bancrofti is the Filaria worm responsible for causing lymphatic filariasis or elephantiasis. It is transmitted to humans through the bite of infected mosquitoes.
In Aschelminthes, the sexes are separate, meaning they are:
- A Gonochoric
- B Monoecious
- C Hermaphrodite
- D Parthenogenetic
Correct answer: Gonochoric
Aschelminthes are gonochoric (dioecious), with distinct male and female individuals. Often, females are longer than males, and fertilization is typically internal.
Ancylostoma is commonly known as the:
- A Hookworm
- B Roundworm
- C Pinworm
- D Whipworm
Correct answer: Hookworm
Ancylostoma duodenale is known as the hookworm. It is an intestinal parasite that attaches to the host's intestinal mucosa to suck blood.
Which level of organization is found in Aschelminthes?
- A Cellular level
- B Tissue level
- C Organ level
- D Organ-system level
Correct answer: Organ-system level
Aschelminthes possess an organ-system level of body organization. They are bilaterally symmetrical, triploblastic, and pseudocoelomate animals.
Corals, which have a skeleton composed of calcium carbonate, belong to the phylum:
- A Cnidaria
- B Porifera
- C Platyhelminthes
- D Echinodermata
Correct answer: Cnidaria
Corals are cnidarians that secrete a hard skeleton made of calcium carbonate. They typically exist in the polyp form and often live in large colonies.
Which of the following is true for the life cycle of Ascaris?
- A It is an endoparasite of the human small intestine
- B It requires a snail as an intermediate host in its cycle
- C It exhibits alternation of generations
- D The adult worm lives freely in the bloodstream
Correct answer: It is an endoparasite of the human small intestine
Ascaris lumbricoides is a common intestinal roundworm found in humans. Infection occurs through the ingestion of water or food contaminated with embryonated eggs.