All Free Biology MCQs with Answers

• A. Osteichthyes-A bony endoskeleton and gills covered by operculum
• B. Reptilia-Left aortic arch & internal fertilization
• C. Nematoda-Triploblastic & acoelomates
• D. Cephalopods-Dorsal nerve cord & bilateral symmetry

Explanation: Osteichthyes is the class that contains fish with bony endoskeletons and gill slits covered by an operculum.

• A. Deuterostomes
• B. Hemichordates
• C. Proterosomes
• D. Aschelminthes

Explanation: These are the animals having a true body cavity or coelom. The cavity is filled with coelomic fluid.

• A. Bony fish
• B. Fish like mammals
• C. Cartilaginous fish
• D. All of these options are correct

Explanation: The S-band is a short wave band that sends out short waves to find any hurdles in the path that are used by cartilaginous fishes for their…

• A. Separate layers of cells
• B. Structures associated with them
• C. Their functions in body
• D. Structures formed from them

Explanation: Option A is wrong because, in triploblastic animals, the three layers represent the structures formed from them instead of separate layers…

• A. Porifera
• B. Ctenophora
• C. Echinodermata
• D. None of the above

Explanation: Euplectella is classified under the phylum Porifera. They belong to the class Hexactinellida, characterized by the skeleton of six-rayed…

• A. The scales on its body are modified into spines for protection against predators
• B. It lays eggs and has mammary glands
• C. The fur on its body is modified into spines, and it is warm-blooded
• D. None of the above

Explanation: The following chart might help explain the characteristics of mammals:

• A. Each body segment has two sets of male and female reproductive organs
• B. The digestive tract develops from endodermal cells in the embryo
• C. The body can be cut into two parts, which are mirror images of each other, in one plane only
• D. None of the above

Explanation: B is correct option because Tapeworms absorb food through their skin. The beef tapeworm is called Taenia saginata.

• A. Pseudocoelom
• B. Enterocoelous
• C. Amphicoelous
• D. Schizocoelous

Explanation: Option D is correct since mesoderm splits in protostomes (annelid, arthropod, and mollusk) which are also called schizocoelous.

• A. Cnidocytes
• B. Gastrozoids
• C. Hydrozoa
• D. Mesoglea

Explanation: Option A is correct since Cnidocytes are the stinging cells that have nematocysts in them and poke them out on being stimulated.

• A. Stipules
• B. Spicules
• C. Spines
• D. Amoeboid cells

Explanation: Option D is correct since amoeboid cells allow sexual reproduction to occur.Option A is incorrect since stipules are not found in…

• A. Muscles and Bones
• B. Hydrostatic skeleton and intestinal fluid
• C. Parapodia and Setea
• D. None of the above.

Explanation: Annelid setae are stiff bristles present on the body. They help, for example, earthworms to attach to the surface and prevent backsliding…

• A. Detrital organic particles
• B. Zooplankton and Small animals
• C. Phytoplanktons
• D. All of these

Explanation: According to research, up to 80% of the food of sponges consists of detrital organic particles, which are tiny pieces of dead or decaying…

• A. Muscles
• B. Hydrostatic skeleton
• C. Parapodia
• D. Setae

Explanation: All annelids except leeches also have chitonous hair-like structures, called setae, projecting from their cuticle.

• A. They have a vertebral column
• B. Their brain is enclosed by the skull
• C. The embryos have gills
• D. The body develops from 3 germinal layers

Explanation: The vertebrates have a vertebral column, something like the notochord. Vertebrates show all the characteristic features of the phylum…

• A. Arachnida
• B. Insecta
• C. Cephalopoda
• D. Myriapoda

Explanation: Correct option:D (It is a fact that Centipedes belong to the class Myriapoda of arthropoda). Centipedes belong to the class Myriapoda.

• A. Arthropods
• B. Fish
• C. Annelids
• D. Nematods

Explanation: Annelids have a hydrostatic skeleton in their body structure.

• A. Tendons and joint capsules
• B. Thorax
• C. Antennae
• D. Abdomen

Explanation: Stretch receptors are mechanoreceptors responsive to the distention of various organs and muscles and are neurologically linked to the…

• A. Glochidium larva
• B. Bipinnaria larva
• C. Trochophore larva
• D. Tomaria larva

Explanation: Trochophore, also called trochosphere, small, translucent, free-swimming larva characteristic of marine annelids and most groups of…

• A. Bilaterally symmetrical and diploblastic
• B. Bilaterally symmetrical and triploblastic
• C. Radially symmetrical and triploblastic
• D. Radially symmetrical and diploblastic

Explanation: Phylum Platyhelminthes belongs to the kingdom Animalia. This phylum includes 13,000 species. The organisms are also known as flatworms.

• A. Early cleavages of the zygote
• B. Ultimate function of the opening to the archenteron
• C. Number of germ layers in the developing embryo
• D. Embryonic origin of the mouth
• E. embryonic origin of the coelom

Explanation: Both deuterostomes and protostomes have three germ layers. The statement that is NOT true among the given options is: "number of germ…