All Free Biology MCQs with Answers

• A. chitin in their exoskeleton
• B. chlicitae
• C. three pairs of legs
• D. two pairs of antennae

Explanation: Crustaceans are the only arthropods with two pairs of antennae, so option D is correct. All arthropods have chitin in their exoskeleton.

• A. spinneret
• B. Carapace
• C. Medriporite
• D. Tube feet

Explanation: Spiders, which belong to the phylum Arthropoda, are predators who trap their prey by producing silk threads.

• A. Cloacas
• B. Bills
• C. Gizzard
• D. chest muscles

Explanation: The shape of the sternum and chest muscles aid birds in flight.

• A. A mammal sucking milk
• B. A dog looking for its food dish
• C. A worm moving away from bright light
• D. A spider spinning a web

Explanation: The correct answer is Option B: 'A dog looking for its food dish.' This behavior is learned because dogs associate the dish with food…

• A. Crustacea
• B. Myriapoda
• C. Arachnida
• D. Hexapoda

Explanation: Spiders belong to the class Arachnida, which includes joint-legged animals like scorpions, ticks, and mites.

• A. Myriapoda
• B. Arychnida
• C. Hexapoda
• D. Crustacean

Explanation: Crustaceans form a very large group of arthropods, which includes crabs, lobsters, crayfish etc.

• A. Bony fishes
• B. Cartllaginous fishes
• C. Lung fishes
• D. Jawless fishes

Explanation: The operculum is a hard, plate-like bony flap that covers the gills of a bony fish protecting the gills and also serves a role in…

• A. Teeth
• B. Sycon
• C. Fresh water mussels
• D. Jelly fish

Explanation: Sycon are sponges that receive food particles with the help of collar cells, therefore are called filter feeders.

• A. Rat
• B. Kangaroo
• C. Duckbilled platypus
• D. Spiny ant eater

Explanation: Viviparous species are those who give birth to living young ones directly instead of laying eggs.

• A. Sea horse
• B. Sea mouse
• C. Sea cucumber
• D. Sea lion

Explanation: Annelids, Molluscs, and arthropods fall into the category of protostomes.

• A. 4
• B. 6
• C. 8
• D. 10

Explanation: Arachnids(spider-like) is a class of Phylum Arthropoda with 4 pairs of legs, so a total of 8 legs.

• A. Disc
• B. Arm
• C. Foot
• D. Siphon

Explanation: The muscular foot has been modified in cephalopods (Octopus) to form the tentacles and the siphon.The siphon is the tubular portion of the…

• A. Brittle star
• B. Scorpion
• C. Chaetopterus
• D. Unio

Explanation: Brittle Stars are Echinoderms which are marine animals having radial symmetry with five parts, often with spines. So it is a deuterostome.

• A. Dogfish
• B. Lamprey
• C. Catfish
• D. Ray fish

Explanation: Maximum number of gill slits present in cyclostomes . Cyclostomes have 6-15 pairs of gills. Lampreys are example of cyclostomes.

• A. Planaria
• B. Earthworm
• C. Cockroach
• D. Snail

Explanation: In planaria, the mouth opens into muscular tubular pharynx which leads into the intestine.

• A. Coral
• B. Sea anemone
• C. Hydra
• D. Jellyfish

Explanation: Corals are unique among coelenterates because they secrete a hard exoskeleton made of calcium carbonate (CaCO3), which is distinct from…

• A. Imprinting
• B. Insight learning
• C. Latent learning
• D. Trial & error learning

Explanation: The complex form of learning that requires the manipulation of mental concepts for developing an adaptive behaviour is called insight…

• A. Annelida
• B. Mollusca
• C. Coelenterata
• D. Echinodermata

Explanation: Phylum Coelenterata is a group of aquatic and marine organisms with a radially symmetrical body.

• A. Annelida
• B. Arthropoda
• C. Echinodermata
• D. Mollusca

Explanation: A hermaphrodite is an organism with both male and female reproductive organs.

• A. Bipinnaria
• B. Radiolaria
• C. Tornaria
• D. Trochophore

Explanation: Balanoglossus is a genus of ocean-dwelling acorn worms (Enteropneusta).