Classification of major phyla upto subclass with examples of Protozoa
- Which of the following is NOT a characteristic of Protozoa?
a) Unicellular eukaryotes
b) Motile using cilia/flagella/pseudopodia
c) Cell wall made of cellulose
d) Heterotrophic nutrition
Answer: (c) Cell wall made of cellulose
Explanation: Protozoa are unicellular eukaryotes that generally lack a cell wall. Instead, they may possess a flexible pellicle or simple plasma membrane. A cell wall made of cellulose is characteristic of plant cells and some algae, not protozoa. - The locomotory structure in Amoeba is:
a) Cilia
b) Flagella
c) Pseudopodia
d) Tentacles
Answer: (c) Pseudopodia
Explanation: Amoeba moves and engulfs food using pseudopodia, which are temporary, flowing extensions of the cytoplasm. These help in both locomotion and phagocytosis. - Plasmodium (malaria parasite) belongs to class:
a) Mastigophora
b) Ciliata
c) Sporozoa
d) Sarcodina
Answer: (c) Sporozoa
Explanation: Sporozoa (now called Apicomplexa) are a group of parasitic protozoans that do not have locomotory structures. Plasmodium, the malaria parasite, reproduces by forming spores and belongs to this group. - Which protozoan causes African sleeping sickness?
a) Entamoeba histolytica
b) Trypanosoma gambiense
c) Giardia intestinalis
d) Paramecium caudatum
Answer: (b) Trypanosoma gambiense
Explanation: Trypanosoma gambiense is transmitted by the bite of the tsetse fly (Glossina) and causes African sleeping sickness, a serious disease affecting the central nervous system. - The contractile vacuole in protozoans helps in:
a) Digestion
b) Osmoregulation
c) Reproduction
d) Respiration
Answer: (b) Osmoregulation
Explanation: The contractile vacuole is a specialized organelle in freshwater protozoans like Paramecium, which expels excess water to maintain internal osmotic balance and prevent cell lysis. - Binary fission is a mode of reproduction in:
a) Plasmodium
b) Amoeba
c) Trypanosoma
d) Monocystis
Answer: (b) Amoeba
Explanation: Amoeba reproduces asexually through binary fission, where the cell divides into two genetically identical daughter cells. It is a common method among many protozoans. - Which protozoan has a macronucleus and micronucleus?
a) Euglena
b) Amoeba
c) Paramecium
d) Leishmania
Answer: (c) Paramecium
Explanation: Paramecium contains two types of nuclei: a macronucleus that controls daily metabolic activities and a micronucleus involved in genetic exchange during conjugation. - Euglena is classified under:
a) Fungi
b) Flagellated Protozoa
c) Ciliated Protozoa
d) Sporozoans
Answer: (b) Flagellated Protozoa
Explanation: Euglena moves using flagella and is classified under flagellated protozoa. It is unique for its mixotrophic nutrition—photosynthetic in light and heterotrophic in dark. - Which disease is caused by Entamoeba histolytica?
a) Malaria
b) Amoebic dysentery
c) Kala-azar
d) Giardiasis
Answer: (b) Amoebic dysentery
Explanation: Entamoeba histolytica infects the human intestine, causing bloody diarrhea and abdominal cramps. Transmission occurs through ingestion of cysts in contaminated food or water. - The sexual reproduction in Paramecium is called:
a) Binary fission
b) Conjugation
c) Budding
d) Sporulation
Answer: (b) Conjugation
Explanation: In conjugation, two Paramecia temporarily fuse and exchange micronuclear material, leading to genetic recombination. This is a form of sexual reproduction in ciliates. - Which protozoan is transmitted by sandfly?
a) Trypanosoma
b) Leishmania donovani
c) Plasmodium
d) Giardia
Answer: (b) Leishmania donovani
Explanation: Leishmania donovani is transmitted by the bite of the female sandfly and causes visceral leishmaniasis or kala-azar, a potentially fatal disease affecting internal organs. - The cyst stage in protozoans helps in:
a) Locomotion
b) Survival under harsh conditions
c) Photosynthesis
d) Sexual reproduction
Answer: (b) Survival under harsh conditions
Explanation: Protozoan cysts are dormant, resistant stages that protect the organism in unfavorable environments, aiding in transmission and survival outside the host. - Which is a free-living protozoan?
a) Plasmodium
b) Trypanosoma
c) Amoeba proteus
d) Leishmania
Answer: (c) Amoeba proteus
Explanation: Amoeba proteus is non-parasitic and lives freely in freshwater ponds, feeding on bacteria and smaller protists by phagocytosis. - Giardia causes:
a) Malaria
b) Diarrhea
c) Sleeping sickness
d) Kala-azar
Answer: (b) Diarrhea
Explanation: Giardia intestinalis causes giardiasis, a diarrheal disease. It infects the small intestine and spreads through ingestion of contaminated water or food. - The locomotory structure in Trypanosoma is:
a) Pseudopodia
b) Flagellum
c) Cilia
d) Tentacles
Answer: (b) Flagellum
Explanation: Trypanosoma moves using a single flagellum attached to the body via an undulating membrane, aiding in motility through host fluids. - Which protozoan shows mixotrophic nutrition?
a) Paramecium
b) Euglena
c) Amoeba
d) Plasmodium
Answer: (b) Euglena
Explanation: Euglena contains chloroplasts for autotrophic photosynthesis and can also ingest food particles heterotrophically, especially in darkness—an example of mixotrophy. - Trichonympha is symbiotic in:
a) Human intestine
b) Termite gut
c) Mosquito salivary glands
d) Tsetse fly midgut
Answer: (b) Termite gut
Explanation: Trichonympha lives symbiotically in the gut of termites and helps in breaking down cellulose, which termites themselves cannot digest. - The infective stage of Plasmodium is:
a) Trophozoite
b) Sporozoite
c) Merozoite
d) Gametocyte
Answer: (b) Sporozoite
Explanation: Sporozoites are injected into the human host by the female Anopheles mosquito. They travel to the liver and initiate the asexual life cycle of Plasmodium. - Which protozoan causes Chagas disease?
a) Trypanosoma brucei
b) Trypanosoma cruzi
c) Leishmania
d) Giardia
Answer: (b) Trypanosoma cruzi
Explanation: Trypanosoma cruzi causes Chagas disease, mainly in Latin America. It is transmitted by reduviid bugs (“kissing bugs”) through their feces entering mucous membranes or wounds. - Noctiluca is an example of:
a) Parasitic protozoan
b) Bioluminescent protozoan
c) Photosynthetic protozoan
d) Ciliated protozoan
Answer: (b) Bioluminescent protozoan
Explanation: Noctiluca scintillans is a marine dinoflagellate that exhibits bioluminescence. It causes glowing in seawater and is also associated with harmful algal blooms (“red tide”).
Special features: Reproduction a Protozoa
- Which is the most common asexual reproduction method in Protozoa?
a) Conjugation
b) Binary fission
c) Syngamy
d) Encystment
Answer: (b) Binary fission
Explanation: Binary fission is the most widespread and simple method of asexual reproduction in protozoa. The nucleus divides mitotically followed by cytoplasmic division, producing two genetically identical daughter cells. It allows rapid population increase. Example: Amoeba, Paramecium. - Multiple fission in Plasmodium is called:
a) Schizogony
b) Sporogony
c) Budding
d) Fragmentation
Answer: (a) Schizogony
Explanation: Schizogony is a form of asexual reproduction in which the nucleus divides multiple times before the cell splits, producing many daughter cells (merozoites). In Plasmodium, this occurs in liver cells and red blood cells. - Sexual reproduction in Paramecium occurs via:
a) Binary fission
b) Conjugation
c) Autogamy
d) Endomixis
Answer: (b) Conjugation
Explanation: Conjugation in Paramecium is a form of sexual reproduction involving two cells that come together to exchange micronuclei. This leads to genetic recombination but does not increase cell number. - The resistant stage during unfavorable conditions is:
a) Trophozoite
b) Cyst
c) Gametocyte
d) Sporozoite
Answer: (b) Cyst
Explanation: Cysts are dormant, protective forms of protozoa that help them survive extreme environmental conditions such as desiccation, low pH, or nutrient deficiency. Entamoeba histolytica forms cysts in feces, which are also the infective form. - Which protozoan reproduces by longitudinal binary fission?
a) Amoeba
b) Euglena
c) Paramecium
d) Plasmodium
Answer: (b) Euglena
Explanation: In Euglena, binary fission occurs along the longitudinal (long) axis of the cell, which is characteristic of flagellated protozoa. Each daughter cell receives one flagellum. - The sexual phase of Plasmodium occurs in:
a) Human liver
b) Mosquito gut
c) Human RBCs
d) Water bodies
Answer: (b) Mosquito gut
Explanation: The sexual phase (sporogony) of Plasmodium occurs in the midgut of the female Anopheles mosquito. The ingested gametocytes undergo fusion to form a zygote, which eventually produces sporozoites. - Autogamy occurs in:
a) Amoeba
b) Paramecium aurelia
c) Trypanosoma
d) Leishmania
Answer: (b) Paramecium aurelia
Explanation: Autogamy is a process where a single cell undergoes nuclear reorganization and self-fertilization. In Paramecium aurelia, this helps rejuvenate the organism without involving another individual. - Which protozoan exhibits alternation of generations?
a) Entamoeba
b) Plasmodium
c) Giardia
d) Noctiluca
Answer: (b) Plasmodium
Explanation: Plasmodium shows alternation of generations involving both asexual reproduction in humans (schizogony, gametogony) and sexual reproduction in mosquitoes (sporogony). This ensures survival in two different hosts. - The infective stage of Entamoeba histolytica is:
a) Trophozoite
b) Quadrinucleate cyst
c) Sporozoite
d) Merozoite
Answer: (b) Quadrinucleate cyst
Explanation: The mature quadrinucleate cyst is the stage that survives passage through stomach acid and initiates infection in the colon. It is excreted in feces and transmits through contaminated water or food. - Endodyogeny is seen in:
a) Paramecium
b) Toxoplasma gondii
c) Euglena
d) Trypanosoma
Answer: (b) Toxoplasma gondii
Explanation: Endodyogeny is a specialized form of asexual reproduction where two daughter cells are formed inside the parent cell. It is typical in Toxoplasma gondii, a parasitic protozoan. - Which is NOT a sexual reproduction method?
a) Conjugation
b) Schizogony
c) Syngamy
d) Autogamy
Answer: (b) Schizogony
Explanation: Schizogony is an asexual process in which multiple daughter cells are produced from one parent. The other three—conjugation, syngamy (fusion of gametes), and autogamy—involve sexual processes with genetic recombination. - Gametogony in Plasmodium produces:
a) Merozoites
b) Gametocytes
c) Sporozoites
d) Trophozoites
Answer: (b) Gametocytes
Explanation: Gametogony is the stage where some merozoites differentiate into male and female gametocytes in human blood. These gametocytes are taken up by mosquitoes and begin the sexual cycle. - Opalina reproduces asexually by:
a) Binary fission
b) Plasmotomy
c) Budding
d) Encystment
Answer: (b) Plasmotomy
Explanation: In Opalina, plasmotomy involves the division of multinucleated cells into two or more multinucleated daughter cells without nuclear division. It is a rare type of asexual reproduction. - Which protozoan shows transverse binary fission?
a) Amoeba
b) Euglena
c) Paramecium
d) Plasmodium
Answer: (c) Paramecium
Explanation: Paramecium divides by transverse binary fission, in which the organism splits across its short axis. This results in two identical daughter cells. - The reproductive stage of Trypanosoma in tsetse fly is:
a) Amastigote
b) Epimastigote
c) Trypomastigote
d) Promastigote
Answer: (b) Epimastigote
Explanation: In the tsetse fly vector, Trypanosoma exists as an epimastigote, which multiplies by binary fission in the fly’s salivary glands before transforming into the infective trypomastigote stage. - Encystment helps protozoans in:
a) Locomotion
b) Surviving drought
c) Sexual reproduction
d) Photosynthesis
Answer: (b) Surviving drought
Explanation: Encystment involves forming a thick-walled dormant cyst, which allows the organism to withstand harsh conditions like desiccation, low temperature, and food scarcity. Example: Amoeba. - Plasmodium gametocytes are ingested by:
a) Human
b) Female Anopheles
c) Contaminated water
d) Sandfly
Answer: (b) Female Anopheles
Explanation: During a blood meal, the female Anopheles mosquito ingests gametocytes from the infected human host. Inside the mosquito, these gametocytes mature and fuse, beginning the sexual phase. - Which protozoan reproduces by budding?
a) Amoeba
b) Arcella
c) Paramecium
d) Plasmodium
Answer: (b) Arcella
Explanation: Arcella, a shelled amoeba, reproduces asexually by budding, where a small part of the parent cell pinches off to form a new individual. This is less common in protozoa. - The sexual cycle of Plasmodium is called:
a) Schizogony
b) Sporogony
c) Gametogony
d) Merogony
Answer: (b) Sporogony
Explanation: Sporogony is the phase of sexual reproduction in Plasmodium that takes place in the mosquito. It results in the production of sporozoites from the zygote, which are then transmitted to humans. - Giardia reproduces asexually by:
a) Multiple fission
b) Longitudinal binary fission
c) Transverse binary fission
d) Plasmotomy
Answer: (b) Longitudinal binary fission
Explanation: In Giardia, the cell divides along the longitudinal axis, producing two identical daughter cells. This process allows rapid multiplication in the host intestine.
Classification of major phyla upto subclass with examples of Porifera
- Which level of organization is found in Porifera?
a) Tissue level
b) Cellular level
c) Organ level
d) Organ system level
Answer: (b) Cellular level
Explanation: Sponges exhibit a cellular level of organization, where cells are specialized for different functions but do not form true tissues or organs. This is the simplest form of multicellularity among animals. - The skeletal structures in sponges are called:
a) Setae
b) Spicules or spongin fibers
c) Chitinous bristles
d) Calcium plates
Answer: (b) Spicules or spongin fibers
Explanation: The internal skeleton of sponges is composed of spicules (made of calcium carbonate or silica) and/or spongin fibers (a type of collagen-like protein). These provide both support and protection. - Water enters sponges through:
a) Osculum
b) Ostia
c) Spongocoel
d) Choanocytes
Answer: (b) Ostia
Explanation: Water carrying food and oxygen enters the sponge’s body through small pores called ostia, located on the body surface. It then flows into the spongocoel and exits through the osculum. - Which cells create water currents in sponges?
a) Amoebocytes
b) Choanocytes (collar cells)
c) Pinacocytes
d) Sclerocytes
Answer: (b) Choanocytes
Explanation: Choanocytes are flagellated cells lining the inner chambers of the sponge. The beating of their flagella creates a water current that draws water in through the ostia and filters food particles. - The simplest sponge body plan is:
a) Asconoid
b) Syconoid
c) Leuconoid
d) Radial
Answer: (a) Asconoid
Explanation: Asconoid sponges (e.g., Leucosolenia) have a simple, tube-like body plan with a central spongocoel and are lined by choanocytes. They are the least efficient in water filtration. - Asexual reproduction in sponges occurs via:
a) Binary fission
b) Budding or gemmules
c) Spores
d) Conjugation
Answer: (b) Budding or gemmules
Explanation: Sponges reproduce asexually by external budding or by forming internal resistant structures called gemmules (in freshwater species like Spongilla), which help survive unfavorable conditions. - The larval form of Porifera is:
a) Planula
b) Parenchymula/Amphiblastula
c) Trochophore
d) Miracidium
Answer: (b) Parenchymula/Amphiblastula
Explanation: These are ciliated, free-swimming larval stages in sponges. Amphiblastula is found in calcareous sponges, while Parenchymula is more common in other classes. - Which class has calcium carbonate spicules?
a) Demospongiae
b) Calcarea
c) Hexactinellida
d) Homoscleromorpha
Answer: (b) Calcarea
Explanation: Class Calcarea includes marine sponges with spicules composed exclusively of calcium carbonate. Example: Sycon, Leucosolenia. - Commercial bath sponges belong to class:
a) Calcarea
b) Demospongiae
c) Hexactinellida
d) Homoscleromorpha
Answer: (b) Demospongiae
Explanation: Demospongiae is the largest class of sponges. Bath sponges (e.g., Spongia officinalis) are soft and flexible due to the presence of spongin fibers and lack of rigid spicules. - Glass sponges (Hexactinellida) are characterized by:
a) Calcareous spicules
b) Siliceous spicules
c) Spongin fibers
d) Chitinous skeleton
Answer: (b) Siliceous spicules
Explanation: Glass sponges (e.g., Euplectella) possess delicate, six-rayed siliceous spicules that often fuse to form a beautiful lattice-like skeleton. - Which is a freshwater sponge?
a) Euplectella
b) Spongilla
c) Sycon
d) Leucosolenia
Answer: (b) Spongilla
Explanation: Spongilla is one of the few freshwater genera of sponges. It inhabits ponds, lakes, and streams and forms gemmules for asexual reproduction. - The outer layer of sponges is formed by:
a) Choanocytes
b) Pinacocytes
c) Amoebocytes
d) Sclerocytes
Answer: (b) Pinacocytes
Explanation: Pinacocytes are flat cells forming the outer epithelial layer (pinacoderm) of sponges, providing protection and maintaining the sponge’s shape. - Nutrient distribution in sponges is performed by:
a) Amoebocytes
b) Choanocytes
c) Sclerocytes
d) Pinacocytes
Answer: (a) Amoebocytes
Explanation: Amoebocytes move through the mesohyl (gelatinous matrix), carrying nutrients from choanocytes to other cells. They also play roles in reproduction and spicule formation. - Which is NOT a Poriferan feature?
a) Filter feeding
b) Hermaphroditism
c) Nerve cells
d) Osculum
Answer: (c) Nerve cells
Explanation: Poriferans lack nerve cells and nervous systems. They are simple multicellular animals that rely on passive mechanisms and cellular coordination instead of nervous responses. - The most complex sponge body plan is:
a) Asconoid
b) Syconoid
c) Leuconoid
d) Radial
Answer: (c) Leuconoid
Explanation: Leuconoid sponges (e.g., Spongilla) have a complex network of incurrent canals and flagellated chambers, increasing surface area for efficient water flow and filter feeding. - Sexual reproduction in sponges involves:
a) Conjugation
b) Sperm and ova
c) Binary fission
d) Fragmentation
Answer: (b) Sperm and ova
Explanation: Sponges reproduce sexually through the formation of sperm and ova. Most are hermaphrodites, meaning both gametes are produced by the same individual, often at different times to avoid self-fertilization. - Hyalonema belongs to class:
a) Calcarea
b) Hexactinellida
c) Demospongiae
d) Homoscleromorpha
Answer: (b) Hexactinellida
Explanation: Hyalonema is a deep-sea glass sponge belonging to Hexactinellida, characterized by long, twisted siliceous spicules forming a root-like stalk. - Sponges are primarily:
a) Predators
b) Filter feeders
c) Parasites
d) Autotrophs
Answer: (b) Filter feeders
Explanation: Sponges filter water to extract tiny food particles like bacteria and plankton. They are sessile and depend on the water current generated by choanocytes. - Which cell produces spicules?
a) Choanocytes
b) Pinacocytes
c) Sclerocytes
d) Amoebocytes
Answer: (c) Sclerocytes
Explanation: Sclerocytes are specialized amoeboid cells that synthesize and secrete the mineral spicules that form the skeleton of the sponge. - The scientific study of sponges is called:
a) Conchology
b) Parazoology
c) Malacology
d) Helminthology
Answer: (b) Parazoology
Explanation: Parazoology is the branch of zoology that deals with Parazoa, a subkingdom which includes sponges. “Para-” refers to their primitive position relative to true tissues (Eumetazoa).
Classification of major phyla upto subclass with examples of cnidaria
- Which level of body organization is found in Cnidaria?
a) Cellular level
b) Tissue level
c) Organ level
d) Organ system level
Answer: (b) Tissue level
Explanation: Cnidarians exhibit tissue-level organization, meaning their cells are organized into distinct tissues that perform specific functions. However, they do not have true organs or organ systems like higher animals. - The stinging cells of Cnidaria are called:
a) Choanocytes
b) Cnidocytes
c) Pinacocytes
d) Sclerocytes
Answer: (b) Cnidocytes
Explanation: Cnidocytes are specialized cells unique to cnidarians. They house nematocysts (stinging structures) used for capturing prey and defense. These are triggered by mechanical or chemical stimuli. - Which body form is sessile in Cnidaria?
a) Polyp
b) Medusa
c) Planula
d) Larva
Answer: (a) Polyp
Explanation: The polyp form is cylindrical and attached to a substrate (sessile). It reproduces asexually and is exemplified by organisms like Hydra and coral polyps. - The larval stage of Cnidaria is called:
a) Planula
b) Trochophore
c) Parenchymula
d) Amphiblastula
Answer: (a) Planula
Explanation: The planula is a free-swimming, ciliated larva that helps in dispersal. It eventually settles and develops into a polyp. - Which class includes jellyfish?
a) Hydrozoa
b) Scyphozoa
c) Anthozoa
d) Cubozoa
Answer: (b) Scyphozoa
Explanation: Scyphozoans are the “true jellyfish” and are mostly medusoid in form. Aurelia is a common example of this class. - Corals belong to class:
a) Hydrozoa
b) Scyphozoa
c) Anthozoa
d) Cubozoa
Answer: (c) Anthozoa
Explanation: Anthozoans include corals and sea anemones. They exist only in the polyp form and are often colonial. Reef-building species like Madrepora belong here. - The body cavity of Cnidaria is called:
a) Spongocoel
b) Gastrovascular cavity
c) Coelom
d) Pseudocoelom
Answer: (b) Gastrovascular cavity
Explanation: This cavity functions both in digestion and distribution of nutrients. It has a single opening that serves as both mouth and anus. - Which is a freshwater Cnidarian?
a) Hydra
b) Physalia
c) Aurelia
d) Adamsia
Answer: (a) Hydra
Explanation: Hydra is a small, freshwater polyp that is sessile and reproduces both sexually and asexually by budding. Others listed are marine. - The phenomenon of alternation between polyp and medusa is called:
a) Metagenesis
b) Metamorphosis
c) Metamerism
d) Parthenogenesis
Answer: (a) Metagenesis
Explanation: Metagenesis is the alternation of generations involving both asexual (polyp) and sexual (medusa) stages in the life cycle, as seen in Obelia. - Which is the most venomous Cnidarian?
a) Hydra
b) Aurelia
c) Chironex (box jellyfish)
d) Adamsia
Answer: (c) Chironex
Explanation: Chironex fleckeri, the box jellyfish, is extremely venomous and can be lethal to humans. Its venom affects the heart and nervous system. - The Portuguese man-of-war (Physalia) is a:
a) True jellyfish
b) Colonial hydrozoan
c) Coral
d) Sea anemone
Answer: (b) Colonial hydrozoan
Explanation: Physalia is not a single animal but a colony of specialized polyps and medusoids. It floats on the surface and has long stinging tentacles. - Which Cnidarian lacks a medusa stage?
a) Obelia
b) Aurelia
c) Adamsia (sea anemone)
d) Physalia
Answer: (c) Adamsia
Explanation: Adamsia (and all Anthozoans) exist only in the polyp form. They do not exhibit metagenesis and do not produce medusae. - The symmetry exhibited by Cnidaria is:
a) Bilateral
b) Radial
c) Spherical
d) Asymmetrical
Answer: (b) Radial
Explanation: Radial symmetry allows these animals to interact with the environment from all directions, which suits their sessile or floating lifestyle. - Which cell type is absent in Cnidaria?
a) Cnidocytes
b) Nerve cells
c) Flame cells
d) Epithelial cells
Answer: (c) Flame cells
Explanation: Flame cells, involved in excretion and osmoregulation, are found in flatworms (Platyhelminthes), not cnidarians. - The mesoglea in Cnidaria is:
a) Cellular
b) Non-cellular gelatinous layer
c) Chitinous
d) Calcareous
Answer: (b) Non-cellular gelatinous layer
Explanation: Mesoglea is an acellular jelly-like layer between the outer epidermis and inner gastrodermis, providing structural support and buoyancy. - Which is an example of coral reef-building Cnidarian?
a) Hydra
b) Physalia
c) Acropora
d) Aurelia
Answer: (c) Acropora
Explanation: Acropora is a genus of stony corals that form hard exoskeletons of calcium carbonate, playing a key role in reef formation. - The class Cubozoa includes:
a) Hydras
b) Moon jellies
c) Box jellyfish
d) Sea fans
Answer: (c) Box jellyfish
Explanation: Cubozoans have a cube-shaped medusa and are known for their speed and potent venom. Chironex is a notorious example. - Which Cnidarian forms symbiotic relationships with clownfish?
a) Physalia
b) Aurelia
c) Heteractis (sea anemone)
d) Obelia
Answer: (c) Heteractis
Explanation: Clownfish live among the tentacles of sea anemones like Heteractis, gaining protection while the anemone benefits from food scraps. - The reproductive polyp in Obelia is called:
a) Hydranth
b) Gonangium
c) Medusoid
d) Planula
Answer: (b) Gonangium
Explanation: In Obelia, the gonangium is the specialized polyp responsible for asexual production of medusae, which are released into the water. - Which Cnidarian is bioluminescent?
a) Hydra
b) Adamsia
c) Aequorea (crystal jelly)
d) Madrepora
Answer: (c) Aequorea
Explanation: Aequorea victoria produces green fluorescent protein (GFP), widely used in molecular biology. Its bioluminescence helps in prey attraction and defense.
Special features: Polymorphism of Siphonophira
- Siphonophores exhibit polymorphism primarily due to:
a) Genetic mutations
b) Division of labor among zooids
c) Environmental stress
d) Parasitic adaptations
Answer: (b)
Explanation: Polymorphism in siphonophores results from the specialization of different zooids within a colony. Each zooid performs a specific function—some are adapted for feeding (gastrozooids), others for reproduction (gonozooids), defense (dactylozooids), flotation (pneumatophore), or locomotion (nectophores). This division of labor enhances survival and efficiency in the marine environment. - Which is a classic example of Siphonophora?
a) Hydra
b) Physalia (Portuguese man-of-war)
c) Aurelia
d) Obelia
Answer: (b)
Explanation: Physalia is a well-known siphonophore. Although it resembles a jellyfish, it is actually a colonial organism made of many specialized zooids working together. Other examples include Nanomia and Praya. - The gas-filled float in Physalia is called:
a) Nectophore
b) Pneumatophore
c) Bract
d) Gonophore
Answer: (b)
Explanation: The pneumatophore is a gas-filled structure at the top of Physalia that keeps the colony afloat. It contains a mixture of gases such as nitrogen, oxygen, and carbon dioxide, and functions like a sail to catch the wind for locomotion. - Which zooid is responsible for feeding in Siphonophores?
a) Gastrozooid
b) Gonozooid
c) Nectophore
d) Palpon
Answer: (a)
Explanation: Gastrozooids are responsible for feeding. They possess tentacles armed with nematocysts (stinging cells) to capture and digest prey, mainly small fish and zooplankton. - Siphonophores belong to which class?
a) Scyphozoa
b) Hydrozoa
c) Anthozoa
d) Cubozoa
Answer: (b)
Explanation: Despite their large size and complex appearance, siphonophores like Physalia belong to the class Hydrozoa, which also includes Hydra and Obelia. They are colonial hydrozoans with polymorphic zooids. - The swimming zooids in Siphonophores are called:
a) Dactylozooids
b) Nectophores
c) Pneumatophores
d) Gonozooids
Answer: (b)
Explanation: Nectophores are muscular, medusoid zooids specialized for propulsion. By rhythmic contraction, they help the colony swim and maintain position in the water column. - Reproductive zooids in Siphonophores are termed:
a) Gastrozooids
b) Gonozooids
c) Pneumatophores
d) Bracts
Answer: (b)
Explanation: Gonozooids are responsible for reproduction. They produce medusa-like structures or gametes, depending on the species, ensuring continuity of the colony. - Defensive zooids in Physalia are called:
a) Dactylozooids
b) Gonozooids
c) Nectophores
d) Gastrozooids
Answer: (a)
Explanation: Dactylozooids are long, tentacle-bearing zooids specialized for defense and prey capture. In Physalia, they can extend several meters and are equipped with potent nematocysts that can sting humans severely. - The “sail” in Physalia is a modified:
a) Gastrozooid
b) Pneumatophore
c) Nectophore
d) Bract
Answer: (b)
Explanation: The pneumatophore acts like a sail that allows the organism to drift with ocean currents and winds. Its translucent, gas-filled structure sits above the water surface. - Which zooid protects smaller zooids in the colony?
a) Nectophore
b) Bract
c) Gastrozooid
d) Gonozooid
Answer: (b)
Explanation: Bracts are specialized leaf-like zooids that cover and protect the more delicate zooids in the colony from predators and mechanical damage. - The venom of Physalia primarily targets:
a) Digestive enzymes
b) Nervous system
c) Respiratory pathways
d) Circulatory system
Answer: (b)
Explanation: The venom released by Physalia’s nematocysts contains neurotoxins that can paralyze or severely affect the nervous system of prey—and humans. In extreme cases, it can cause respiratory or cardiac complications. - Which is NOT a Siphonophore?
a) Physalia
b) Nanomia
c) Aurelia
d) Praya
Answer: (c)
Explanation: Aurelia is a scyphozoan jellyfish (class Scyphozoa), not a siphonophore. In contrast, Physalia, Nanomia, and Praya are all members of the order Siphonophora within class Hydrozoa. - The “fishing tentacles” of Physalia are:
a) Gonozooids
b) Dactylozooids
c) Nectophores
d) Bracts
Answer: (b)
Explanation: Dactylozooids in Physalia can reach up to 30 meters and are used like fishing lines. They paralyze and capture prey using their venom-laden nematocysts. - Siphonophores are primarily:
a) Freshwater organisms
b) Marine predators
c) Parasites
d) Filter feeders
Answer: (b)
Explanation: Siphonophores are exclusively marine and are active predators. Species like Praya dubia are among the longest known animals and feed on planktonic organisms in deep oceans. - The colonial nature of Siphonophores arises from:
a) Binary fission
b) Budding of zooids
c) Fragmentation
d) Spore formation
Answer: (b)
Explanation: Siphonophores develop through a process of budding, where new zooids are produced from a common stem and remain attached, forming a complex colonial body. - The scientific study of Siphonophores falls under:
a) Conchology
b) Cnidology
c) Helminthology
d) Phycology
Answer: (b)
Explanation: Cnidology is the branch of zoology that studies cnidarians, including corals, jellyfish, hydra, and siphonophores. It involves anatomy, ecology, venom, and evolution of these organisms. - Physalia is often confused with:
a) True jellyfish
b) Colonial hydrozoans
c) Corals
d) Sea anemones
Answer: (a)
Explanation: Due to its bell-like float and tentacles, Physalia is often mistaken for a jellyfish (Scyphozoa). However, it is a colonial hydrozoan siphonophore composed of specialized zooids. - Which zooid is absent in Physalia?
a) Gastrozooid
b) Dactylozooid
c) Medusozooid
d) Pneumatophore
Answer: (c)
Explanation: Physalia lacks medusae as free-swimming reproductive forms. Instead, reproduction occurs via gonozooids within the colony, which produce gametes without a medusoid stage.
Classification of major phyla upto subclass with examples of etenophora
- Ctenophores are commonly called:
a) Sea walnuts
b) Comb jellies
c) Both (a) and (b)
d) Portuguese man-of-war
Answer: (c)
Explanation: Ctenophores are popularly known as “sea walnuts” due to their shape and “comb jellies” due to the presence of comb-like ciliary plates. Examples include Pleurobrachia (sea gooseberry) and Cestum (Venus’ girdle). The Portuguese man-of-war, however, is a cnidarian (not a ctenophore). - The locomotory structures in ctenophores are:
a) Cnidocytes
b) Comb plates (ctenes)
c) Pseudopodia
d) Flagella
Answer: (b)
Explanation: Ctenophores move using 8 rows of ciliated comb plates called ctenes, which beat in a coordinated fashion to propel the animal. This is unique among animals, making ctenophores the largest organisms that swim by means of cilia. - Ctenophores exhibit:
a) Radial symmetry
b) Biradial symmetry
c) Bilateral symmetry
d) Asymmetry
Answer: (b)
Explanation: Though similar to cnidarians in being radially symmetrical, ctenophores actually exhibit biradial symmetry, a derived form of radial symmetry with two planes of division. This feature sets them apart evolutionarily. - The adhesive cells unique to ctenophores are called:
a) Nematocysts
b) Colloblasts (lasso cells)
c) Choanocytes
d) Pinacocytes
Answer: (b)
Explanation: Ctenophores possess colloblasts, which are sticky, adhesive cells used to capture prey. These differ from the nematocysts (stinging cells) of cnidarians. Colloblasts release a glue-like substance rather than a toxin. - Which is NOT a ctenophore?
a) Pleurobrachia
b) Beroe
c) Aurelia
d) Cestum
Answer: (c)
Explanation: Aurelia is a scyphozoan jellyfish, a cnidarian, not a ctenophore. The others (Pleurobrachia, Beroe, Cestum) are well-known genera of ctenophores. - The digestive system in ctenophores is:
a) Incomplete (blind sac)
b) Complete (mouth + anal pores)
c) Absent
d) Extracellular only
Answer: (b)
Explanation: Unlike cnidarians, ctenophores have a complete digestive tract with a mouth and two anal pores through which waste exits. This is a significant advancement in animal evolution. - Bioluminescence in ctenophores is produced by:
a) Spicules
b) Photocytes in comb rows
c) Colloblasts
d) Gastrodermal cells
Answer: (b)
Explanation: Specialized photocytes, found near the comb rows, produce light through bioluminescence. This is thought to help in camouflage, communication, or luring prey in dark marine environments. - The body cavity of ctenophores is a:
a) Coelom
b) Gastrovascular cavity
c) Pseudocoelom
d) Spongocoel
Answer: (b)
Explanation: Ctenophores have a gastrovascular cavity where digestion and internal nutrient distribution occur. They are acoelomate, meaning they lack a true coelom (body cavity). - Ctenophores lack:
a) Cilia
b) Respiratory and excretory systems
c) Locomotion
d) Bioluminescence
Answer: (b)
Explanation: Ctenophores do not have specialized respiratory or excretory organs. These functions occur through diffusion across the body surface, which is feasible due to their aquatic and gelatinous structure. - The statocyst in ctenophores helps in:
a) Digestion
b) Balance and orientation
c) Reproduction
d) Prey capture
Answer: (b)
Explanation: The statocyst is a sensory organ located at the aboral end of the ctenophore. It contains statoliths that detect gravity, helping the animal maintain orientation in water. - Which ctenophore is flattened like a ribbon?
a) Pleurobrachia
b) Cestum (Venus’ girdle)
c) Beroe
d) Mnemiopsis
Answer: (b)
Explanation: Cestum, commonly called Venus’ girdle, is laterally compressed and ribbon-like in appearance. It is adapted for graceful, undulating movements in water. - Ctenophores are classified under:
a) Radiata
b) Diploblastic animals
c) Both (a) and (b)
d) Triploblastic animals
Answer: (c)
Explanation: Ctenophores are diploblastic (developing from two germ layers – ectoderm and endoderm) and are traditionally placed under Radiata along with cnidarians due to their radial or biradial symmetry. - The invasive ctenophore disrupting Black Sea ecology is:
a) Cestum
b) Mnemiopsis leidyi
c) Pleurobrachia
d) Beroe ovata
Answer: (b)
Explanation: Mnemiopsis leidyi, a bioluminescent ctenophore, invaded the Black Sea, causing ecological imbalance by consuming large quantities of zooplankton, fish eggs, and larvae, thus harming native fish populations. - Ctenophores differ from cnidarians in having:
a) Nematocysts
b) Colloblasts + biradial symmetry
c) Medusa stage
d) Polyp stage
Answer: (b)
Explanation: Ctenophores possess colloblasts instead of nematocysts and show biradial symmetry, unlike cnidarians which have radial symmetry and nematocysts. Also, ctenophores do not have distinct polyp or medusa stages like cnidarians.
Classification of major phyla upto subclass with examples of Platyheminthes
- Platyhelminthes exhibit:
a) Radial symmetry
b) Bilateral symmetry
c) Spherical symmetry
d) Asymmetry
Answer: (b)
Explanation: Platyhelminthes are the first group in animal evolution to exhibit bilateral symmetry, which allows for cephalization (concentration of sensory organs at one end). This body plan enables more directed movement and predation. - The excretory organs in Platyhelminthes are:
a) Nephridia
b) Flame cells (protonephridia)
c) Malpighian tubules
d) Kidneys
Answer: (b)
Explanation: Flame cells, also called protonephridia, are specialized cells that function in osmoregulation and excretion. These are found in freshwater species like Planaria, where they help eliminate excess water and metabolic waste. - Which class includes free-living flatworms?
a) Turbellaria
b) Trematoda
c) Cestoda
d) Monogenea
Answer: (a)
Explanation: Class Turbellaria includes mostly non-parasitic, free-living flatworms such as Planaria. They are often found in freshwater and possess remarkable regenerative abilities. - The intermediate host of Fasciola hepatica (liver fluke) is:
a) Human
b) Snail (Lymnaea)
c) Pig
d) Mosquito
Answer: (b)
Explanation: The liver fluke uses snails of genus Lymnaea as its intermediate host, where larval stages like sporocyst and redia develop. Sheep or cattle serve as the definitive host, where the adult fluke matures in the bile duct. - Tapeworms (Cestoda) lack:
a) Reproductive organs
b) Digestive system
c) Nervous system
d) Excretory system
Answer: (b)
Explanation: Cestodes like Taenia lack a digestive system. Instead, they absorb pre-digested nutrients directly from the host’s intestine through their tegument, an adaptation to a parasitic lifestyle. - The scolex of Taenia has:
a) Flame cells
b) Hooks and suckers
c) Cilia
d) Nematocysts
Answer: (b)
Explanation: The scolex is the head region of tapeworms and bears hooks and suckers to firmly attach to the host’s intestinal wall, ensuring the parasite remains in place despite peristaltic movements. - Which disease is caused by Schistosoma?
a) Elephantiasis
b) Schistosomiasis (snail fever)
c) Sleeping sickness
d) Hydatidosis
Answer: (b)
Explanation: Schistosoma species cause Schistosomiasis, a serious disease spread by contact with contaminated freshwater containing the parasite’s larval stage. The disease involves blood flukes and can damage internal organs. - The larval stage of Taenia solium infective to humans is:
a) Miracidium
b) Cysticercus
c) Redia
d) Proglottid
Answer: (b)
Explanation: The cysticercus larva develops in pig muscle and becomes infective to humans when undercooked pork is consumed. This can lead to taeniasis or cysticercosis if larvae migrate to tissues like the brain. - Monogeneans are mostly:
a) Free-living
b) Ectoparasites on fish gills
c) Human blood flukes
d) Soil nematodes
Answer: (b)
Explanation: Monogeneans are a class of parasitic flatworms that are ectoparasites primarily on fish gills and skin. Example: Gyrodactylus, causing gill damage and stress in aquatic animals. - The tegument in cestodes is for:
a) Locomotion
b) Nutrient absorption
c) Reproduction
d) Respiration
Answer: (b)
Explanation: The tegument is a syncytial outer covering in cestodes that aids in nutrient absorption, protecting the parasite from host digestive enzymes and allowing uptake of simple nutrients like glucose. - Which is NOT a Platyhelminth?
a) Planaria
b) Fasciola
c) Ascaris
d) Taenia
Answer: (c)
Explanation: Ascaris is a nematode (roundworm), not a flatworm. It is cylindrical, has a pseudocoelom, and belongs to Phylum Nematoda, unlike the flat, acoelomate body plan of Platyhelminthes. - The “ladder-like” nervous system is seen in:
a) Planaria
b) Taenia
c) Fasciola
d) Schistosoma
Answer: (a)
Explanation: Planaria exhibit a ladder-type nervous system, with two longitudinal nerve cords connected by transverse nerves, enabling simple coordinated movement and sensory response. - The diagnostic feature of cestodes is:
a) Flame cells
b) Proglottids
c) Cilia
d) Radula
Answer: (b)
Explanation: Proglottids are repeated reproductive segments in cestodes like Taenia. Each contains male and female organs, allowing for high reproductive output. Their shedding helps in transmission to new hosts. - Platyhelminthes are:
a) Acoelomate
b) Triploblastic + acoelomate
c) Diploblastic
d) Pseudocoelomate
Answer: (b)
Explanation: Platyhelminthes are triploblastic (three germ layers: ectoderm, mesoderm, endoderm) and acoelomate, meaning they lack a true body cavity. This simple body structure limits organ development but suits flat, parasitic or aquatic lifestyles.
Classification of major phyla upto subclass with examples of Nematoda
- Nematodes exhibit:
a) Radial symmetry
b) Bilateral symmetry
c) Spherical symmetry
d) Asymmetry
Answer: (b)
Explanation: Nematodes are bilaterally symmetrical, which means the left and right sides of their bodies are mirror images. This symmetry allows for directional movement and development of distinct body regions. Nematodes are also the first animals to exhibit a pseudocoelom. - The body cavity in nematodes is called:
a) Coelom
b) Pseudocoelom
c) Gastrovascular cavity
d) Hemocoel
Answer: (b)
Explanation: A pseudocoelom is a body cavity not completely lined by mesoderm. In nematodes, it acts as a hydrostatic skeleton and helps distribute nutrients and waste throughout the body. - Which nematode causes Elephantiasis?
a) Ascaris lumbricoides
b) Wuchereria bancrofti
c) Ancylostoma duodenale
d) Enterobius vermicularis
Answer: (b)
Explanation: Wuchereria bancrofti is transmitted by Culex mosquitoes and resides in the lymphatic vessels, causing their blockage. This leads to severe swelling of limbs, a condition known as elephantiasis or lymphatic filariasis. - The cuticle of nematodes is composed of:
a) Chitin
b) Collagen
c) Cellulose
d) Spongin
Answer: (b)
Explanation: The cuticle is a thick, flexible, and non-cellular outer covering made of collagen. It protects nematodes from digestive enzymes of the host and environmental stress and is periodically shed (molted) during growth. - Which is a free-living nematode?
a) Ancylostoma
b) Caenorhabditis elegans
c) Wuchereria
d) Trichinella
Answer: (b)
Explanation: Caenorhabditis elegans is a non-parasitic nematode widely used as a model organism in developmental biology and genetics due to its transparent body and well-mapped genome. - The infective stage of Ascaris to humans is:
a) Adult worm
b) Embryonated egg
c) Filariform larva
d) Cyst
Answer: (b)
Explanation: The embryonated egg containing the larva is the infective stage. Humans acquire infection by ingesting contaminated food or water containing these eggs, which hatch in the intestine. - “Hookworm” refers to:
a) Enterobius
b) Ancylostoma duodenale
c) Trichuris
d) Dracunculus
Answer: (b)
Explanation: Ancylostoma duodenale is commonly known as hookworm because of the hook-like shape of its anterior end. It attaches to the intestinal wall and feeds on blood, causing iron-deficiency anemia. - The larval stage of Wuchereria transmitted by mosquitoes is:
a) Rhabditiform
b) Microfilariae
c) Cercaria
d) Miracidium
Answer: (b)
Explanation: Microfilariae are the larval forms present in the bloodstream. These are picked up by mosquitoes during feeding and develop further within the vector before being transmitted to new hosts. - Pinworm infection is caused by:
a) Trichinella spiralis
b) Enterobius vermicularis
c) Strongyloides
d) Loa loa
Answer: (b)
Explanation: Enterobius vermicularis, or pinworm, is a common parasite in children. The female lays eggs around the anus at night, causing intense itching. Reinfection often occurs due to scratching and ingestion of eggs. - Trichinella spiralis is transmitted through:
a) Contaminated water
b) Undercooked pork
c) Mosquito bite
d) Soil contact
Answer: (b)
Explanation: Humans contract Trichinella spiralis by eating undercooked pork containing encysted larvae. The larvae are released in the intestine and migrate to muscles, forming painful cysts (trichinosis). - Which is NOT a nematode?
a) Ascaris
b) Ancylostoma
c) Taenia solium
d) Trichuris
Answer: (c)
Explanation: Taenia solium is a cestode (flatworm or tapeworm), not a nematode. The others are true roundworms (phylum Nematoda). - The “tube-within-a-tube” body plan is seen in:
a) Platyhelminthes
b) Nematoda
c) Porifera
d) Cnidaria
Answer: (b)
Explanation: Nematodes exhibit a complete digestive system with a mouth and anus, representing a “tube within a tube” body plan. This allows efficient unidirectional food digestion and absorption. - The diagnostic feature of nematodes is:
a) Flame cells
b) Longitudinal muscles only
c) Segmented body
d) Radula
Answer: (b)
Explanation: Nematodes possess only longitudinal muscles and lack circular muscles. This results in a characteristic whip-like thrashing motion. They do not have flame cells (found in flatworms), segmentation, or radula. - Nematodes are:
a) Acoelomate
b) Pseudocoelomate
c) Triploblastic + pseudocoelomate
d) Diploblastic
Answer: (c)
Explanation: Nematodes are triploblastic animals with a pseudocoelom—meaning they have three germ layers (ectoderm, mesoderm, and endoderm) and a body cavity not entirely lined by mesoderm.
Classification of major phyla upto subclass with examples of Annelida
- The key feature of Annelida is:
a) Radial symmetry
b) Metameric segmentation
c) Pseudocoelom
d) Diploblastic organization
Answer: (b)
Explanation: Metameric segmentation refers to the serial repetition of similar body segments, both internally and externally. This is a defining characteristic of annelids like earthworms (Pheretima) and Nereis. It provides greater mobility and coordination. - The excretory organs in Annelida are called:
a) Flame cells
b) Nephridia
c) Malpighian tubules
d) Kidneys
Answer: (b)
Explanation: Nephridia are tubular excretory structures that filter nitrogenous wastes (mainly urea or ammonia) from body fluids. In annelids like Nereis, both protonephridia and metanephridia types are seen, depending on the species and developmental stage. - Which class includes earthworms?
a) Polychaeta
b) Oligochaeta
c) Hirudinea
d) Archiannelida
Answer: (b)
Explanation: Earthworms belong to class Oligochaeta. They lack parapodia, have few setae, and are hermaphroditic. Pheretima posthuma is a common terrestrial oligochaete. - The locomotory structures in Nereis are:
a) Setae only
b) Parapodia with setae
c) Suckers
d) Cilia
Answer: (b)
Explanation: Nereis, a marine polychaete, uses lateral paddle-like outgrowths called parapodia with embedded setae for locomotion and respiration. This helps in swimming and crawling. - Leeches belong to class:
a) Polychaeta
b) Oligochaeta
c) Hirudinea
d) Cestoda
Answer: (c)
Explanation: Leeches (e.g., Hirudinaria) are part of class Hirudinea. They have a fixed number of segments, are mostly ectoparasitic, lack setae, and have suckers for attachment. - The coelom in Annelida is:
a) Absent
b) True coelom (schizocoelom)
c) Pseudocoelom
d) Haemocoel
Answer: (b)
Explanation: Annelids are the first phylum in evolution to have a true coelom (body cavity fully lined by mesoderm), formed via schizocoely. It helps in organ development and acts as a hydrostatic skeleton. - The circulatory system in Annelida is:
a) Open
b) Closed
c) Absent
d) Lacunar
Answer: (b)
Explanation: Most annelids (e.g., earthworms) possess a closed circulatory system with blood confined to vessels, enhancing efficient transport of gases and nutrients. - Chloragogen cells in earthworms function like:
a) Kidney
b) Liver
c) Heart
d) Lung
Answer: (b)
Explanation: Chloragogen cells are analogous to vertebrate liver cells. They surround the intestine and store glycogen and fat, and detoxify nitrogenous waste before it’s excreted by nephridia. - The clitellum in earthworms is involved in:
a) Respiration
b) Cocoon formation
c) Locomotion
d) Excretion
Answer: (b)
Explanation: The clitellum is a glandular, thickened section of the body in sexually mature earthworms that secretes mucus during copulation and later forms the cocoon for egg deposition. - Which Annelid is used as bait?
a) Hirudinaria
b) Nereis
c) Tubifex
d) Aphrodite
Answer: (b)
Explanation: Nereis, commonly called “ragworm” or “clam worm”, is used by fishermen as bait due to its availability and ease of collection in coastal areas. - Which is NOT an Annelid?
a) Pheretima
b) Nereis
c) Planaria
d) Hirudinaria
Answer: (c)
Explanation: Planaria is a free-living flatworm belonging to phylum Platyhelminthes, not Annelida. It is a triploblastic, acoelomate organism with bilateral symmetry but lacks segmentation. - The respiratory pigment in Annelids is:
a) Hemocyanin
b) Hemoglobin
c) Chlorocruorin
d) All of these
Answer: (d)
Explanation: Different annelids use different pigments for oxygen transport. Earthworms use hemoglobin, while some marine polychaetes like Sabella use chlorocruorin. Others may use hemerythrin or hemocyanin. - The larval form of Nereis is:
a) Trochophore
b) Trochophore and metatrochophore
c) Veliger
d) Miracidium
Answer: (b)
Explanation: Nereis undergoes indirect development, forming a trochophore larva, which may further develop into a metatrochophore. These larvae are ciliated and free-swimming, characteristic of many protostomes. - Annelids are:
a) Acoelomate
b) Pseudocoelomate
c) Triploblastic + coelomate
d) Diploblastic
Answer: (c)
Explanation: Annelids develop from three germ layers (ectoderm, mesoderm, endoderm), and possess a true coelom formed from mesoderm. This triploblastic and coelomate condition supports organ development and specialization.
Classification of major phyla upto subclass with examples of Arthropoda
- The largest phylum in Animalia is:
a) Mollusca
b) Arthropoda
c) Chordata
d) Annelida
Answer: (b)
Explanation: Arthropoda is the largest phylum in the animal kingdom, accounting for approximately 84% of all known animal species. It includes insects, arachnids, crustaceans, and myriapods. Their segmented bodies and jointed appendages are key distinguishing features. - The exoskeleton of arthropods is made of:
a) Cellulose
b) Chitin + proteins
c) Calcium carbonate
d) Spongin
Answer: (b)
Explanation: The arthropod exoskeleton is composed of chitin, a polysaccharide, along with proteins. This hard, protective covering supports the body and provides points for muscle attachment. In crustaceans, it may also be calcified. - Which class has the maximum number of species?
a) Arachnida
b) Insecta
c) Crustacea
d) Myriapoda
Answer: (b)
Explanation: Insecta is the most diverse class, with over one million described species. They are characterized by a three-part body (head, thorax, abdomen), six legs, and usually two pairs of wings (e.g., beetles, flies, butterflies). - Compound eyes are present in:
a) Scorpions
b) Houseflies
c) Ticks
d) Millipedes
Answer: (b)
Explanation: Compound eyes, composed of multiple units called ommatidia, are typical of many insects like houseflies (Musca). These eyes provide a broad field of view and detect motion efficiently. - Which arthropod transmits malaria?
a) Culex
b) Anopheles
c) Aedes
d) Xenopsylla
Answer: (b)
Explanation: Female Anopheles mosquitoes are the primary vectors of malaria. They transmit Plasmodium parasites through their piercing-sucking mouthparts during blood meals. - Which is NOT a crustacean?
a) Palaemon (prawn)
b) Daphnia (water flea)
c) Limulus (horseshoe crab)
d) Cancer (crab)
Answer: (c)
Explanation: Limulus is a horseshoe crab and belongs to the class Merostomata under the subphylum Chelicerata, not Crustacea. Crustaceans typically include aquatic arthropods like prawns and crabs. - The respiratory organs in spiders are:
a) Gills
b) Book lungs + tracheae
c) Skin
d) Parapodia
Answer: (b)
Explanation: Spiders breathe through book lungs (stacked plate-like structures) and/or tracheal tubes. This dual respiratory system is an adaptation for terrestrial life. - Which arthropod shows metamorphosis?
a) Scolopendra (centipede)
b) Pieris (butterfly)
c) Buthus (scorpion)
d) Limulus
Answer: (b)
Explanation: Pieris (cabbage butterfly) undergoes complete metamorphosis: egg → larva (caterpillar) → pupa → adult. This is a characteristic feature of many insects, especially Lepidoptera. - The mouthparts of mosquitoes are:
a) Chewing
b) Piercing-sucking
c) Sponging
d) Siphoning
Answer: (b)
Explanation: Female mosquitoes have piercing-sucking mouthparts adapted for blood-feeding. The elongated proboscis pierces skin and draws blood; males feed on nectar and lack this adaptation. - Which arthropod is NOT an insect?
a) Apis (honeybee)
b) Periplaneta
c) Scolopendra
d) Bombyx (silkworm)
Answer: (c)
Explanation: Scolopendra is a centipede, belonging to the class Chilopoda (subphylum Myriapoda). It is not an insect as it has many body segments and more than three pairs of legs. - The excretory organs of prawns are:
a) Malpighian tubules
b) Antennal glands
c) Flame cells
d) Nephridia
Answer: (b)
Explanation: Crustaceans like prawns excrete nitrogenous wastes through antennal or green glands, located at the base of their antennae. These glands filter waste from the hemolymph. - Which arthropod is a living fossil?
a) Daphnia
b) Limulus
c) Periplaneta
d) Bombyx
Answer: (b)
Explanation: Limulus (horseshoe crab) is termed a “living fossil” because its morphology has remained nearly unchanged for over 450 million years, reflecting evolutionary stasis. - The number of legs in insects is:
a) 4
b) 6
c) 8
d) Variable
Answer: (b)
Explanation: Insects have three pairs of legs (total 6), attached to the thorax. This is a key taxonomic characteristic distinguishing them from arachnids (8 legs) and myriapods (many legs). - Arthropods are:
a) Acoelomate
b) Pseudocoelomate
c) Coelomate + segmented
d) Diploblastic
Answer: (c)
Explanation: Arthropods are triploblastic, coelomate animals with segmented bodies. However, their true coelom is reduced to a hemocoel (blood-filled cavity), and segmentation is often fused into body regions (tagmata).
Special features: Respiration in Arthropod
- Which respiratory organ is found in spiders?
a) Gills
b) Book lungs
c) Tracheal tubes
d) Skin
Answer: (b)
Explanation: Spiders like Plexippus possess book lungs, which are stacked, leaf-like structures located in the abdominal region. These allow passive diffusion of gases and are suited for terrestrial respiration. - Aquatic arthropods like prawns respire through:
a) Gills
b) Tracheae
c) Book lungs
d) Spiracles
Answer: (a)
Explanation: In prawns (e.g., Palaemon), respiration occurs through gills that are richly supplied with blood and located in branchial chambers under the carapace. These help in aquatic gas exchange. - The respiratory pigment in arthropods is:
a) Hemoglobin
b) Hemocyanin
c) Chlorocruorin
d) Hemerythrin
Answer: (b)
Explanation: Hemocyanin is a copper-containing respiratory pigment found in many arthropods and mollusks. Unlike hemoglobin, it is dissolved in the hemolymph and turns blue upon oxygenation. - Tracheal respiration is found in:
a) Scorpions
b) Cockroaches
c) Crabs
d) Millipedes
Answer: (b)
Explanation: Cockroaches (e.g., Periplaneta) have a tracheal system comprising branched tubes that deliver oxygen directly to tissues. The system opens outside through spiracles. - Spiracles in insects are associated with:
a) Digestion
b) Tracheal system
c) Excretion
d) Reproduction
Answer: (b)
Explanation: Spiracles are external openings that lead into the tracheal tubes. They regulate gas exchange and water loss, essential for respiration in terrestrial insects like Musca domestica. - Which arthropod uses gills modified for land respiration?
a) Limulus
b) Porcellio (woodlouse)
c) Daphnia
d) Palaemon
Answer: (b)
Explanation: Woodlice (Porcellio) are terrestrial isopods that have developed pseudotracheae—a modified form of gill adapted for gas exchange in moist environments. - The respiratory organ of Limulus (horseshoe crab) is:
a) Book gills
b) Tracheae
c) Lungs
d) Skin
Answer: (a)
Explanation: Limulus (a marine chelicerate) uses book gills located on the ventral side of the abdomen for aquatic respiration. These consist of flat lamellae that resemble pages of a book. - Which insect lacks spiracles and tracheae?
a) Periplaneta
b) Apis
c) Collembola (springtail)
d) Bombyx
Answer: (c)
Explanation: Collembola are primitive, tiny insects that rely on cutaneous respiration due to the absence of spiracles and a tracheal system. Gas exchange occurs directly through the moist body surface. - The air sacs in flying insects:
a) Store water
b) Enhance oxygen supply
c) Produce sounds
d) Digest food
Answer: (b)
Explanation: In flying insects such as Apis, air sacs are extensions of the tracheal system that increase the efficiency of oxygen delivery, especially during high-energy flight activities. - Which arthropod respires through parapodia?
a) Palaemon
b) Scolopendra
c) Nereis
d) Limulus
Answer: (c)
Explanation: Nereis is not an arthropod but an annelid (polychaete worm). It respires through parapodia—paired, fleshy outgrowths used for locomotion and gas exchange. This is a common distractor. - The respiratory organ of Buthus (scorpion) is:
a) Tracheae
b) Book lungs
c) Gills
d) Skin
Answer: (b)
Explanation: Buthus, like other scorpions, has four pairs of book lungs located in the mesosoma. These lungs function efficiently in dry terrestrial environments for gaseous exchange. - Which is NOT a terrestrial arthropod respiratory structure?
a) Tracheae
b) Book lungs
c) Ctenidia
d) Spiracles
Answer: (c)
Explanation: Ctenidia are comb-like gills found in mollusks (e.g., snails, bivalves), not arthropods. Arthropods use tracheae, book lungs, and spiracles for terrestrial respiration. - The tracheal system is most efficient in:
a) Millipedes
b) Flying insects
c) Spiders
d) Crustaceans
Answer: (b)
Explanation: Flying insects like Drosophila require large amounts of oxygen. Their highly branched tracheal system and air sacs support rapid oxygen diffusion for sustained flight. - Hemocyanin is dissolved in:
a) RBCs
b) Hemolymph
c) Coelomic fluid
d) Nephridia
Answer: (b)
Explanation: Unlike vertebrates, arthropods lack red blood cells. Hemocyanin, their respiratory pigment, is directly dissolved in hemolymph (their circulatory fluid), which bathes tissues in an open circulatory system.
Classification of major phyla upto subclass with examples of Mollusca
- The second largest phylum in Animalia is:
a) Arthropoda
b) Mollusca
c) Chordata
d) Annelida
Answer: (b)
Explanation: Mollusca is the second-largest phylum after Arthropoda, with over 85,000 described species. They are soft-bodied, often shelled animals including snails, octopuses, and mussels, and exhibit great morphological diversity. - The radula is present in all except:
a) Pila
b) Loligo
c) Unio
d) Sepia
Answer: (c)
Explanation: Unio, a bivalve, lacks a radula. Bivalves are filter feeders and instead use ciliated gills to capture food particles. Radula (a tongue-like rasping organ) is characteristic of most other molluscs like gastropods and cephalopods. - Which class includes octopuses?
a) Gastropoda
b) Cephalopoda
c) Pelecypoda
d) Scaphopoda
Answer: (b)
Explanation: Octopuses belong to Class Cephalopoda, characterized by a distinct head, bilateral body symmetry, and tentacles. Example: Octopus vulgaris has eight arms and shows advanced intelligence among invertebrates. - The respiratory organ in freshwater mussel is:
a) Pulmonary sac
b) Ctenidia (gills)
c) Book lungs
d) Tracheae
Answer: (b)
Explanation: In bivalves like Unio, respiration and filter feeding occur via ctenidia (plate-like gills). These gills are large and covered with cilia to aid water movement and capture food particles. - The shell in Sepia is:
a) External spiral
b) Internal (cuttlebone)
c) Absent
d) Bivalved
Answer: (b)
Explanation: Sepia (cuttlefish) has an internal calcareous shell called the cuttlebone, which helps in buoyancy control. Unlike gastropods, their shell is not external. - The coelom in molluscs is:
a) Absent
b) Reduced to pericardial cavity
c) Well-developed
d) Pseudocoelom
Answer: (b)
Explanation: Molluscs are coelomates, but their true coelom is highly reduced and restricted to the pericardial cavity and nephridia. The main body cavity is a hemocoel filled with blood. - Which mollusc shows torsion?
a) Pila
b) Unio
c) Sepia
d) Dentalium
Answer: (a)
Explanation: Pila (apple snail) undergoes torsion during larval development—a 180° twisting of the visceral mass. This causes the anus and mantle cavity to shift near the head. - The ink sac is a defense organ in:
a) Pila
b) Loligo
c) Unio
d) Dentalium
Answer: (b)
Explanation: Loligo (squid) possesses an ink sac that releases dark melanin-rich fluid to create a smoke screen. This defense mechanism confuses predators and aids in escape. - Osphradium in molluscs is used for:
a) Excretion
b) Testing water quality
c) Digestion
d) Reproduction
Answer: (b)
Explanation: The osphradium is a chemosensory organ found near the gills in molluscs like Pila. It tests the chemical nature of incoming water for silt and food particles. - Which is a terrestrial mollusc?
a) Unio
b) Helix
c) Sepia
d) Dentalium
Answer: (b)
Explanation: Helix (garden snail) is adapted for terrestrial life with a modified lung-like pallial cavity. It respires atmospheric air and shows behavioral and structural adaptations to avoid desiccation. - Which mollusc produces pearls?
a) Pila
b) Pinctada
c) Sepia
d) Loligo
Answer: (b)
Explanation: Pinctada (pearl oyster) secretes layers of nacre (mother of pearl) around irritants that enter the mantle cavity, eventually forming pearls. This is a defense mechanism against foreign particles. - The larval form of Unio is:
a) Trochophore
b) Glochidium
c) Veliger
d) Miracidium
Answer: (b)
Explanation: Unio (a freshwater mussel) produces a specialized parasitic larva called glochidium, which temporarily attaches to fish gills or fins before settling to the bottom. - The blood pigment in Octopus is:
a) Hemoglobin
b) Hemocyanin
c) Chlorocruorin
d) Hemerythrin
Answer: (b)
Explanation: Octopus has hemocyanin, a copper-based pigment dissolved in hemolymph. It turns blue when oxygenated and helps oxygen transport in cold, low-oxygen marine environments. - Molluscs are:
a) Diploblastic
b) Triploblastic + bilaterally symmetrical
c) Pseudocoelomate
d) Asymmetrical
Answer: (b)
Explanation: Molluscs are triploblastic and show bilateral symmetry. However, some gastropods (like Pila) become secondarily asymmetrical due to torsion. They have organ-system level organization and true coelom (though reduced).
Special features: Nervous system in Gastropod
- The nervous system in gastropods is:
a) Diffuse net
b) Ganglionated
c) Ladder-like
d) Absent
Answer: (b)
Explanation: Gastropods like Pila have a ganglionated nervous system, meaning the system is organized into clusters of nerve cells called ganglia. These ganglia (cerebral, pedal, pleural, visceral, buccal) are connected by commissures and connectives, allowing efficient coordination of sensory and motor activities. - Which ganglion is associated with the digestive system in Pila?
a) Cerebral
b) Buccal
c) Pedal
d) Pleural
Answer: (b)
Explanation: The buccal ganglia are closely related to the mouth and pharyngeal regions, especially controlling radula movement used for rasping food. It plays a major role in feeding coordination in gastropods. - Torsion in gastropods affects the nervous system by:
a) Eliminating ganglia
b) Creating a “twisted” nerve ring
c) Fusing all ganglia
d) Developing a brain
Answer: (b)
Explanation: Torsion causes a 180° rotation of the visceral mass, which results in crossed nerve cords. This leads to a twisted arrangement of the pleuro-pedal connectives, forming a characteristic figure-8 nerve ring—a hallmark of gastropods. - The statocyst in gastropods is connected to the:
a) Buccal ganglion
b) Cerebral ganglion
c) Pedal ganglion
d) Visceral ganglion
Answer: (c)
Explanation: Statocysts are balance organs located near the foot and are connected to the pedal ganglia, which coordinate locomotion. They help the animal detect gravity and orientation—vital for movement in species like Lymnaea. - Which neurotransmitter is common in gastropods?
a) Dopamine
b) Acetylcholine
c) Serotonin
d) GABA
Answer: (b)
Explanation: Acetylcholine is a major excitatory neurotransmitter in gastropods, playing roles in muscle contraction, synaptic transmission, and locomotion. Studies in Aplysia and Lymnaea confirm its abundance. - The largest ganglion in Pila is:
a) Cerebral
b) Visceral
c) Pedal
d) Pleural
Answer: (b)
Explanation: The visceral ganglion is the largest in Pila, lying deep in the visceral mass. It controls the heart, intestine, and other visceral organs, making it essential for autonomic functions. - The osphradium is innervated by the:
a) Pedal ganglion
b) Pleural ganglion
c) Buccal ganglion
d) Cerebral ganglion
Answer: (b)
Explanation: The osphradium (a chemoreceptor organ that detects water quality) is innervated by the pleural ganglion. It helps molluscs like Pila test for sediment or chemicals in the water before it enters the mantle cavity. - The “twisted” nerve ring in gastropods includes:
a) Only cerebral ganglia
b) Cerebral, pleural, and pedal ganglia
c) Visceral ganglia only
d) Buccal and cerebral ganglia
Answer: (b)
Explanation: The twisted (chiastoneury) nerve ring of gastropods involves cerebral, pleural, and pedal ganglia. This configuration arises after torsion and is used as a taxonomic feature in molluscan classification. - The pedal ganglion controls:
a) Radula movement
b) Foot muscles
c) Shell secretion
d) Reproduction
Answer: (b)
Explanation: The pedal ganglia regulate motor control of the foot, essential for crawling and burrowing. For instance, in Helix, it coordinates muscular contraction of the foot for slow gliding locomotion. - Which gastropod is a model for neurobiology studies?
a) Pila globosa
b) Aplysia californica
c) Lymnaea stagnalis
d) Conus geographus
Answer: (b)
Explanation: Aplysia californica (sea hare) is widely used in neurobiology for studying learning and memory due to its large, accessible neurons. Research on its gill-withdrawal reflex laid the foundation for modern neurophysiology. - The cerebral ganglia in gastropods are analogous to:
a) Vertebrate spinal cord
b) Vertebrate brain
c) Insect Malpighian tubules
d) Annelid nephridia
Answer: (b)
Explanation: The cerebral ganglia serve as the main processing center, receiving input from sensory organs and coordinating behavior, much like a brain in higher animals. - The visceral ganglion innervates the:
a) Foot
b) Heart and digestive organs
c) Radula
d) Tentacles
Answer: (b)
Explanation: The visceral ganglia control the heart, intestine, and reproductive structures, functioning like an autonomic nervous system in gastropods like Helix and Pila. - The neurotransmitter involved in Aplysia’s gill withdrawal reflex is:
a) Dopamine
b) Serotonin
c) GABA
d) Glutamate
Answer: (b)
Explanation: Serotonin enhances synaptic strength in Aplysia, increasing the duration and intensity of the gill-withdrawal reflex—a classic example of sensitization and short-term memory. - Gastropod nervous systems are studied for:
a) Photosynthesis
b) Neuroplasticity and memory
c) Blood clotting
d) Shell formation
Answer: (b)
Explanation: Gastropods like Aplysia and Lymnaea are studied for learning, neuroplasticity, and memory, contributing to understanding human brain function and neurological disorders like Alzheimer’s.
Classification of major phyla upto subclass with examples of Echinodermata
- Echinoderms exhibit:
a) Bilateral symmetry
b) Pentaradial symmetry (adults)
c) Spherical symmetry
d) Asymmetry
Answer: (b)
Explanation: Adult echinoderms such as starfish (Asterias) exhibit pentaradial symmetry, meaning their body is arranged in five (or multiples of five) repeating parts around a central axis. However, their larvae are bilaterally symmetrical, which is indicative of their evolutionary link to bilateral animals. - The water vascular system is unique to:
a) Mollusca
b) Echinodermata
c) Arthropoda
d) Annelida
Answer: (b)
Explanation: Echinoderms possess a distinctive water vascular system, which is a network of hydraulic canals ending in tube feet. This system plays a key role in locomotion, food handling, respiration, and sensory perception. - Which class includes “brittle stars”?
a) Asteroidea
b) Ophiuroidea
c) Echinoidea
d) Holothuroidea
Answer: (b)
Explanation: Brittle stars belong to class Ophiuroidea, characterized by long, slender, flexible arms that are sharply distinct from the central disc. They exhibit rapid, snake-like movements, unlike the slow motion of true starfish. - The madreporite is part of the:
a) Digestive system
b) Water vascular system
c) Nervous system
d) Reproductive system
Answer: (b)
Explanation: The madreporite is a porous, sieve-like structure on the aboral surface through which seawater enters the water vascular system, initiating hydraulic pressure needed for the function of tube feet. - Which echinoderm is edible?
a) Asterias
b) Echinus
c) Holothuria (sea cucumber)
d) Antedon
Answer: (c)
Explanation: Holothuria, a sea cucumber, is edible and widely consumed in Asian cuisine. It is processed into a delicacy known as beche-de-mer, valued for its nutritional and medicinal properties. - Pedicellariae in starfish are used for:
a) Digestion
b) Defense and cleaning
c) Reproduction
d) Respiration
Answer: (b)
Explanation: Pedicellariae are small, claw-like appendages found on the surface of starfish. They help in protecting the body from parasites and debris by constantly cleaning the surface and even capturing small prey. - The skeleton of echinoderms is made of:
a) Chitin
b) Calcium carbonate ossicles
c) Silica
d) Cartilage
Answer: (b)
Explanation: Echinoderms have an endoskeleton composed of calcium carbonate ossicles, which are often spiny or form plates beneath the skin. This structure provides support and protection while allowing flexibility. - Which echinoderm lacks arms?
a) Ophiothrix
b) Echinus (sea urchin)
c) Antedon
d) Asterias
Answer: (b)
Explanation: Echinus (sea urchin) has a rounded or globular body without distinct arms. Its surface is covered with spines, and it moves using tube feet and movable spines. - The larval form of Asterias is:
a) Trochophore
b) Bipinnaria → Brachiolaria
c) Glochidium
d) Veliger
Answer: (b)
Explanation: The development of Asterias includes a bipinnaria larva followed by a brachiolaria stage, both bilaterally symmetrical. These free-swimming forms metamorphose into the pentaradial adult. - Which echinoderm is sessile?
a) Asterias
b) Ophiothrix
c) Antedon (feather star)
d) Holothuria
Answer: (c)
Explanation: Antedon, a feather star (Crinoidea), is sessile in its early adult life. It attaches to the substrate using cirri. Though later it may become free-moving, it remains mostly sedentary compared to other echinoderms. - Which is NOT an echinoderm?
a) Cucumaria
b) Aurelia
c) Echinus
d) Ophiura
Answer: (b)
Explanation: Aurelia is a cnidarian (a jellyfish), belonging to phylum Cnidaria. The others—Cucumaria (sea cucumber), Echinus (sea urchin), and Ophiura (brittle star)—are all echinoderms. - The ambulacral groove is found in:
a) Asterias
b) Echinus
c) Holothuria
d) Antedon
Answer: (a)
Explanation: The ambulacral groove is a depression on the oral surface of Asterias (starfish), containing rows of tube feet used for locomotion and handling food. - The respiratory tree is present in:
a) Starfish
b) Sea cucumbers
c) Sea urchins
d) Brittle stars
Answer: (b)
Explanation: Sea cucumbers like Holothuria possess a respiratory tree, a branched internal structure connected to the cloaca that functions in gas exchange via cloacal pumping. - Echinoderms are:
a) Protostomes
b) Deuterostomes
c) Acoelomates
d) Pseudocoelomates
Answer: (b)
Explanation: Echinoderms are deuterostomes, meaning during embryonic development, the blastopore becomes the anus. This trait is shared with chordates and sets them apart from protostomes like annelids and arthropods.
Special features: Water vascular system in Starfish
- The water vascular system is unique to:
a) Mollusca
b) Echinodermata
c) Arthropoda
d) Annelida
Answer: (b)
Explanation: The water vascular system is a defining feature of echinoderms, absent in all other phyla. It is a network of fluid-filled canals used for locomotion, feeding, and respiration. It operates hydraulic structures like tube feet (e.g., in Asterias). - The entry point of water into the system is the:
a) Tube foot
b) Madreporite
c) Ambulacral groove
d) Radial canal
Answer: (b)
Explanation: The madreporite is a porous, sieve-like plate located on the aboral (upper) surface. It allows seawater to enter the water vascular system and filters out debris. - Which structure connects the madreporite to the ring canal?
a) Radial canal
b) Stone canal
c) Lateral canal
d) Polian vesicle
Answer: (b)
Explanation: The stone canal is a short duct made of calcareous walls that transports water from the madreporite to the central ring canal. It is often reinforced with spicules. - The radial canals supply water to:
a) Digestive glands
b) Tube feet
c) Pedicellariae
d) Dermal branchiae
Answer: (b)
Explanation: Radial canals extend into each arm and give rise to lateral canals that connect to ampullae and tube feet. This enables coordinated locomotion and attachment to surfaces. - Contraction of ampullae results in:
a) Water intake
b) Tube foot extension
c) Spine movement
d) Food capture
Answer: (b)
Explanation: When the ampulla (a muscular sac) contracts, it forces water into the tube foot, causing it to extend. This hydraulic mechanism allows starfish to move or hold prey. - Polian vesicles are attached to the:
a) Radial canals
b) Ring canal
c) Stone canal
d) Madreporite
Answer: (b)
Explanation: Polian vesicles are sac-like structures that store extra fluid and help maintain pressure within the water vascular system, ensuring consistent hydraulic function. - Tube feet are primarily used for:
a) Respiration
b) Locomotion and feeding
c) Excretion
d) Reproduction
Answer: (b)
Explanation: Tube feet function as tiny suckers for movement and gripping prey. In starfish, tube feet can apply sustained force to open bivalves for feeding. - The valve controlling water flow into tube feet is the:
a) Madreporite valve
b) Terminal tentacle
c) Lateral valve
d) Tiedemann’s body
Answer: (b)
Explanation: Each tube foot ends in a suction cup and contains a terminal tentacle or valve that regulates water flow. This controls extension and retraction during locomotion. - Tiedemann’s bodies are associated with:
a) Digestion
b) Fluid filtration/production
c) Nerve impulse transmission
d) Gamete production
Answer: (b)
Explanation: Tiedemann’s bodies are pouch-like organs on the ring canal that produce coelomocytes and help in filtering the water vascular fluid, ensuring cleanliness and function. - Which structure is NOT part of the water vascular system?
a) Radial canal
b) Ampulla
c) Pedicellariae
d) Stone canal
Answer: (c)
Explanation: Pedicellariae are small pincer-like structures used for defense and cleaning. They are part of the body wall, not the water vascular system. - The water vascular system develops from the:
a) Endoderm
b) Coelomic mesoderm
c) Ectoderm
d) Archenteron
Answer: (b)
Explanation: The water vascular system originates from the left mesocoel (a coelomic compartment). It is mesodermal in origin, forming part of the unique coelomic structures of echinoderms. - In which class is the water vascular system most developed?
a) Asteroidea
b) Ophiuroidea
c) Holothuroidea
d) Crinoidea
Answer: (a)
Explanation: In starfish (Asteroidea), the water vascular system is well-developed and easily observed, with distinct madreporite, stone canal, ring canal, radial canals, ampullae, and tube feet. - The hydraulic mechanism of tube feet is powered by:
a) Muscle contractions alone
b) Water pressure changes
c) Ciliary action
d) Electrical impulses
Answer: (b)
Explanation: The action of tube feet depends on the generation and regulation of water pressure by contracting ampullae. Muscle contraction plus fluid dynamics drive their extension and retraction. - Damage to the ring canal would impair:
a) Digestion
b) Movement in all arms
c) Spine flexibility
d) Light detection
Answer: (b)
Explanation: The ring canal is the central hub of the water vascular system. It supplies water to all radial canals. Damage would paralyze all arms due to failure in hydraulic transmission.
