Practice these 50 MCQs on Animal Kingdom (Protozoa to Chordates) tailored for MEC Nepal MBBS Entrance. These questions cover general characteristics, classification, and specific examples.
Click to Reveal Answer
Correct Answer: B
Explanation: The contractile vacuole collects excess water from the cytoplasm and expels it to the outside, maintaining the osmotic balance, especially in freshwater protozoans like Amoeba.
Click to Reveal Answer
Correct Answer: C
Explanation: Archaeocytes are undifferentiated amoeboid cells that are totipotent, meaning they can differentiate into any other cell type (e.g., sex cells, scleroblasts) and are crucial for regeneration.
Click to Reveal Answer
Correct Answer: A
Explanation: The Ascon type is the simplest canal system where water flows directly through Ostia into the Spongocoel and out via the Osculum. It is characteristic of Leucosolenia.
Click to Reveal Answer
Correct Answer: B
Explanation: Cnidoblasts (or Cnidocytes) contain stinging capsules called Nematocysts, used for offense and defense. This is the defining feature of Phylum Cnidaria.
Click to Reveal Answer
Correct Answer: B
Explanation: Obelia exhibits Metagenesis where the asexual polyp generation alternates with the sexual medusa generation.
Click to Reveal Answer
Correct Answer: C
Explanation: Ctenophores (Comb Jellies) possess eight external rows of ciliated comb plates (ctenes) which aid in locomotion.
Click to Reveal Answer
Correct Answer: B
Explanation: Flame cells (Solenocytes or Protonephridia) are the specialized excretory and osmoregulatory structures in Flatworms.
Click to Reveal Answer
Correct Answer: B
Explanation: Tapeworms (Taenia) show pseudometamerism (strobilization), where proglottids are formed by budding from the neck, unlike true metamerism in Annelids where segments arise from the embryonic teloblast.
Click to Reveal Answer
Correct Answer: B
Explanation: In Nematodes like Ascaris, the epidermis is continuous without cell boundaries and contains scattered nuclei, a condition known as syncytial.
Click to Reveal Answer
Correct Answer: B
Explanation: Aschelminthes (Nematodes) are the first to possess a complete alimentary canal with a distinct mouth and anus.
Click to Reveal Answer
Correct Answer: C
Explanation: The glandular clitellum (segments 14-16 in Pheretima) secretes mucus and albumen to form the cocoon in which fertilization and development take place.
Click to Reveal Answer
Correct Answer: C
Explanation: Arthropods have an **open** circulatory system where blood (haemolymph) flows through open spaces called sinuses (haemocoel), not distinct blood vessels.
Click to Reveal Answer
Correct Answer: B
Explanation: Peripatus (Walking worm) has segmented nephridia and worm-like body (Annelid characters) but also tracheal respiration and claws (Arthropod characters).
Click to Reveal Answer
Correct Answer: C
Explanation: Malpighian tubules are blind tubules suspended in the haemolymph that absorb nitrogenous waste (mainly uric acid) and discharge it into the gut.
Click to Reveal Answer
Correct Answer: B
Explanation: Haemocyanin is a copper-containing pigment found in the plasma of Molluscs and some Arthropods, giving the blood a blue color when oxygenated.
Click to Reveal Answer
Correct Answer: C
Explanation: Torsion is characteristic of Gastropoda (Snails/Slugs). It brings the mantle cavity and anus to an anterior position over the head.
Click to Reveal Answer
Correct Answer: C
Explanation: The water vascular system is a unique hydraulic system in Echinoderms used for locomotion (tube feet), food capture, and respiration. Note: Porifera has a *Canal* system.
Click to Reveal Answer
Correct Answer: B
Explanation: Echinoderm larvae are bilaterally symmetrical, but during metamorphosis, they develop into adults with pentamerous radial symmetry.
Click to Reveal Answer
Correct Answer: B
Explanation: The Proboscis gland (or Glomerulus) situated in the proboscis carries out excretion in Hemichordates.
Click to Reveal Answer
Correct Answer: D
Explanation: Chordates have a **dorsal hollow** nerve cord. Non-chordates typically have a ventral solid nerve cord.
Click to Reveal Answer
Correct Answer: B
Explanation: In Urochordata (Tunicates like Herdmania), the advanced tadpole larva with a notochord degenerates into a simpler, sessile adult, a process called retrogressive metamorphosis.
Click to Reveal Answer
Correct Answer: C
Explanation: The name Cephalochordata implies the notochord extends into the head region. It persists along the entire length of the body throughout the animal's life.
Click to Reveal Answer
Correct Answer: A
Explanation: Petromyzon (Lamprey) has a prolonged larval stage called Ammocoete which is freshwater and filter-feeding, structurally resembling Amphioxus.
Click to Reveal Answer
Correct Answer: C
Explanation: Placoid scales (dermal denticles) are characteristic of cartilaginous fishes like sharks. Bony fishes typically have cycloid or ctenoid scales.
Click to Reveal Answer
Correct Answer: B
Explanation: The fish heart (2-chambered) receives deoxygenated blood from the body and pumps it to the gills for oxygenation. It never handles oxygenated blood.
Click to Reveal Answer
Correct Answer: A
Explanation: Latimeria is a Coelacanth fish thought to be extinct but rediscovered. It belongs to the group Sarcopterygii (Lobe-finned fishes).
Click to Reveal Answer
Correct Answer: C
Explanation: The Axolotl larva of Ambystoma retains its external gills and lives in water while becoming sexually mature, a phenomenon known as Neoteny or Paedomorphosis.
Click to Reveal Answer
Correct Answer: A
Explanation: Reptiles and Birds have a Monocondylic skull (single occipital condyle). Amphibians and Mammals have a Dicondylic skull.
Click to Reveal Answer
Correct Answer: C
Explanation: Jacobson's organ (Vomeronasal organ) is an auxiliary olfactory sense organ found in many animals, particularly well-developed in snakes and lizards.
Click to Reveal Answer
Correct Answer: B
Explanation: Pneumatic bones are hollow and filled with air cavities connected to air sacs, reducing body weight to facilitate flight in birds.
Click to Reveal Answer
Correct Answer: C
Explanation: The Syrinx is located at the base of the trachea (at the bifurcation of bronchi) and is responsible for producing sound in birds. Mammals use the Larynx.
Click to Reveal Answer
Correct Answer: C
Explanation: Archaeopteryx possesses reptilian characters (teeth, tail, claws) and avian characters (feathers, wings, beak), linking the two classes.
Click to Reveal Answer
Correct Answer: C
Explanation: While A, B, and D are found in other classes (like Birds), the muscular Diaphragm separating the thoracic and abdominal cavities is unique to Mammals.
Click to Reveal Answer
Correct Answer: B
Explanation: Almost all mammals, from the giraffe to the mouse, have exactly 7 cervical vertebrae. Exceptions are rare (e.g., Sloths).
Click to Reveal Answer
Correct Answer: B
Explanation: Prototherians are primitive egg-laying mammals. They lay reptilian-like eggs but produce milk to feed their young.
Click to Reveal Answer
Correct Answer: B
Explanation: Wuchereria bancrofti is a roundworm (Nematode/Aschelminthes) causing Elephantiasis. Fasciola is a Flatworm; Hirudinaria and Nereis are Annelids.
Click to Reveal Answer
Correct Answer: C
Explanation: The Radula is a file-like organ located in the mouth of Molluscs (except Bivalves) used for scraping food.
Click to Reveal Answer
Correct Answer: C
Explanation: Aschelminthes (Roundworms) have a pseudocoelom derived from the embryonic blastocoel, not lined by mesoderm on both sides.
Click to Reveal Answer
Correct Answer: A
Explanation: The Organ of Bojanus acts as a kidney (metanephridium) in some Molluscs like Unio (Freshwater mussel).
Click to Reveal Answer
Correct Answer: C
Explanation: Pearl oysters (e.g., Pinctada) belong to class Pelecypoda (Bivalvia). The pearl is formed as a secretion of the mantle against a foreign particle.
Click to Reveal Answer
Correct Answer: B
Explanation: The Trochophore larva is a common ciliated larva found in many marine Annelids and Molluscs, indicating an evolutionary relationship.
Click to Reveal Answer
Correct Answer: B
Explanation: Platyhelminthes (Flatworms) are the first triploblastic phylum (3 germ layers) but lack a body cavity (Acoelomate).
Click to Reveal Answer
Correct Answer: B
Explanation: Aristotle's Lantern is a complex 5-jawed chewing apparatus found in Sea Urchins (Class Echinoidea) for scraping algae.
Click to Reveal Answer
Correct Answer: B
Explanation: Cartilaginous fishes (Sharks, Rays) have internal fertilization. Males possess claspers on pelvic fins for sperm transfer.
Click to Reveal Answer
Correct Answer: B
Explanation: Cartilaginous fishes lack an air bladder, so they must swim constantly to avoid sinking. Bony fishes have air bladders.
Click to Reveal Answer
Correct Answer: B
Explanation: Arthropoda is the largest phylum, including insects, crustaceans, arachnids, etc. Mollusca is the second largest.
Click to Reveal Answer
Correct Answer: C
Explanation: Pythons are constrictors and are non-poisonous. Naja, Bungarus, and Vipera are venomous.
Click to Reveal Answer
Correct Answer: B
Explanation: Reptiles generally have a 3-chambered heart with a partially divided ventricle (except Crocodiles, which have 4). Amphibians have a 3-chambered heart with a single ventricle.
Click to Reveal Answer
Correct Answer: A
Explanation: Porocytes are tube-like cells that form the ostia (pores) in the body wall of sponges, allowing water to enter.
Click to Reveal Answer
Correct Answer: B
Explanation: This follows the standard phylogenetic order: Cellular level (Porifera) -> Tissue level (Cnidaria) -> Organ level/Acoelomate (Platyhelminthes) -> Pseudocoelomate (Aschelminthes).
No comments:
Post a Comment