Free Biodiversity and Variety of Life MCQs with Answers

1341. Biradial symmetry and lack of cnidoblasts are the characteristics of:

• A. Hydra and starfish
• B. Starfish and sea anemone
• C. Ctenoplana and Beroe
• D. Aurelia and Paramecium

Explanation: Ctenophora is a small phylum of exclusively marine, invertebrate animals. Ctenoplana and Beroe are examples of ctenophora. They have biradial symmetry (a combination of radial and bilateral symmetries). They lack the specialized stinging cells (nematocysts) found in coelenterates, but one species (Haeckelia rubra) incorporates those of its jellyfish prey for its own defense.

1342. Which one of the following is a matching set of a phylum and its three examples?

• A. Porifera-Spongilla, Euplectella and Pennatula
• B. Cnidaria-Bonellia, Physalia and Aurelia
• C. Platyhelminthes-Planaria, Schistosoma and Enterobius
• D. Mollusca-Loligo, Teredo and Octopus

Explanation: Mollusca includes animals that have soft bodies, usually furnished with a shell. The body is often divided into a head with eyes or tentacles, a muscular foot, and a visceral mass housing the organs. Loligo (squid or sea arrow), Teredo (shipworm), and Octopus are some examples. In option (a), Spongilla and Euplectella belong to Porifera, but Pennatula (the sea pen or sea feather) belongs to Coelenterata. In option (b), Physalia and Aurelia belong to Cnidaria, but Bonellia belongs to the phylum Annelida. In option (c), Planaria and Schistosoma belong to Platyhelminthes, but Enterobius (pinworm) belongs to aschaleminthes.

1343. Which of the following animals have scattered cells with cell tissue grade organisation?

• A. Sponge
• B. Hydra
• C. Liver fluke
• D. Ascaris

Explanation: Hydra shows a tissue level of organization. This means its body is made up of many cells that are grouped into two main layers (tissues), and these tissues have specialized functions.Sponges are simpler and show only a cellular level of organization. Their cells work independently, without forming true tissues.Liver fluke and Ascaris are more advanced and show an organ-system level of organization. Their cells form tissues, tissues form organs, and the organs work together in systems (like digestive or reproductive systems) to keep the body functioning.

1344. The most appropriate term to describe the life cycle of Obelia is:

• A. Metamorphosis
• B. Neoteny
• C. Metagenesis
• D. All of these.

Explanation: Obelia belong to the Phylum Coelenterata. In Obelia, the lifecycle includes two clearly defined phases i.e a fixed polypoid phase (hydroid colony) and a pelagic medusoid phase. Hydroid colony has no gonads and reproduces by asexual budding to give rise to medusae. On the other hand, medusae reproduce exclusively a by sexual method (ova and sperms) to give rise to new hydroid colonies. This fact apparently seems to have given rise to the idea of alternation of generations, also called metagenesis.

1345. The formation of a canal system in sponges is due to:

• A. Folding of inner walls
• B. Gastrovascular system
• C. Reproduction
• D. Porous walls

Explanation: Canal system in sponges develops due to folding of body wall. Three types of canal systems in sponges are ascon type, sycon type and leucon type. Leucon type of canal system is most advanced and develops by folding of body wall. Ascon type of canal system is most primitive and shows minimal foldingSo, the correct answer is 'Folding of inner walls'

1346. Radial symmetry is usually exhibited in animals which:

• A. Are attached to the substratum
• B. Have one opening of alimentary canal
• C. Live in water
• D. Have ciliary mode of feeding

Explanation: The organisms attached to the substratum possess radial symmetry in all vertical planes. All the animals belonging to cnidaria (e.g. jellyfish) and echinodermata (e.g. starfish) are radially symmetrical and typically sessile in their adult form. In radial symmetry, the parts in an organ or organism, when cut through the centre in any direction, produce two halves that are mirror images of each other.

1347. What is true about Taenia saginata?

• A. Life history has pig as intermediate host
• B. There are two large suckers on scolex
• C. Rostellar hooks are absent
• D. Rostellum has double circle of hooks

Explanation: The beef tapeworm Taenia saginata is similar to the pork tapeworm Taenia solium, in structure and life history. It is the commonest tapeworm of man with a much greater incidence than that of T. solium. Scolex bears four strong, rounded, adhesive suckers but lacks hooks and rostellum.

1348. The bullfrog of India is:

• A. Rana tigrina
• B. R. sylvatica
• C. R. ecutesbeiana
• D. R. esculenta

Explanation: The common Indian bull frog Rana tigrina lives in or near permanent freshwater lakes, ponds and streams. It is in the water most of the time. It lives near water mainly for two reasons: (i) To keep skin moist to continue with cutaneous respiration, and (ii) To immediately jump or slip into wate to escape from enemies.

1349. Aristotle's lantern occurs in which class?

• A. Echinoidea
• B. Asteroidea
• C. Holothuroidea
• D. Ophiuroidea

Explanation: Aristotle's lantern occurs in the Class Echinoidea. Five teeth surrounding the mouth are attached to a masticatory apparatus call Aristotle's lantern. It is named Aristiotle's lantern after its discoverer and because it resembles an ancient Greek ship lantern. It is situated within the test and projects slightly through the mouth. It consists of five large calcareous plates, called pyramids or alveoli. By means of special protractor and retractor muscles, the lantern can be partially protracted and retracted through the mouth. Aristotle's lantern is used in feeding.

1350. The simplest type of canal system in Porifera is:

• A. Ascon type
• B. Leucon type
• C. Sycon type
• D. Radial type

Explanation: Sponges belong to the Phylum Porifera. Ostia, spongocoel and osculum together form a canal system which is characteristic of all sponges. Canal system of Leucosolenia is of ascon type. It is the simplest type of canal system found in sponges. Water enters directly through ostia into the central spongocoel, which is lined by choanocytes, and leaves through osculum. Sycon type of canal system is found in Sycons and Leucon type is found in Spongilla. There is no canal system named as a radial type.