All Free Biology MCQs with Answers

• A. Roundworms
• B. Flatworms
• C. Hookworms
• D. Threadworms
• E. Pinworms

Explanation: The phylum Platyhelminthes consists of flatworms, which are named for their flat, dorsoventrally flattened bodies.

• A. Fishes
• B. Reptiles
• C. Birds
• D. Amphibians
• E. A B and C

Explanation: The skin of most fishes is covered with scales. Placoid scales in sharks and rays, cosmoid scales in lungfishes and some fossil fishes…

• A. Pisces
• B. Aves
• C. Reptiles
• D. Amphibians

Explanation: Amphibia is a class of vertebrates that includes frogs, toads, newts, and salamanders.

• A. They have a vertebral column
• B. The brain is enclosed by the skull
• C. The embryos have gills
• D. All of these

Explanation: Vertebrates belong to phylum Chordata primarily because they exhibit several defining features, including a vertebral column (backbone), a…

• A. Nematodes
• B. Arthropods
• C. Molluscs
• D. None of these

Explanation: Arthropods are believed to have a common origin with annelids. Arthropods, which include insects, spiders, crustaceans, and other…

• A. Head
• B. Dorsal muscular foot
• C. Dorsal visceral body
• D. Both A and B

Explanation: The correct option is C. The mantle in molluscs is a significant anatomical feature that forms a protective layer over the dorsal visceral…

• A. Haemoglobin
• B. None
• C. Hemocyanin
• D. Hemolymph

Explanation: Haemoglobin is an oxygen carrying respiratory pigment found in chordates. It is found in the erythrocytes of these animals.

• A. Pidgeon
• B. Elephant
• C. Sheep
• D. Humans

Explanation: Option A is correct since oviparous animals are animals that produce young using eggs that are hatched after they have been laid by the…

• A. Amphibians
• B. Birds
• C. Mammals
• D. Reptiles

Explanation: Reptile eggs, including those of snakes and many turtles, are characterized by their leathery shells, which are flexible and often adhere…

• A. Earthworm
• B. Cockroach
• C. Butterfly
• D. Sting ray

Explanation: Option D is correct since stingray is a deuterostome.Option A is incorrect since the earthworm is an annelid that belongs to the…

• A. Muscles
• B. Hydrostatic skeleton
• C. Parapodia
• D. Setae
• E. A,C and D

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

• A. Mollusca
• B. Echinoderms
• C. Flatworms
• D. Sponges

Explanation: Echinoderms exhibit both radial and bilateral symmetry. During larval stages, echinoderms have bilateral symmetry whereas they have…

• A. They show bilateral symmetry
• B. They show both radial and bilateral symmetry
• C. They are all protostomes
• D. They are all deuterostomes

Explanation: Triploblastic animals are characterized by having three primary germ layers: ectoderm, mesoderm, and endoderm.

• A. Prawn has one pairs of antennae
• B. Nematocysts are characteristics of the phylum cnidaria
• C. Millepedes have two pairs of appendages in each segment of the body
• D. Animals belonging to phylum porifera are marine and fresh water

Explanation: Prawns have two pairs of antennae, one on either side, just below the antennules. They are sensory, excretory, and balancing in function.

• A. Running birds
• B. Migratory birds
• C. Flightless birds
• D. Four-toed birds

Explanation: The ostrich, penguin, and kiwi are all flightless birds. This category best captures their shared trait of being unable to fly, though…

• A. Sac type digestive system
• B. Well-developed respiratory system
• C. Parenchyma fills the body space
• D. Well-developed excretory system

Explanation: The correct answer is Option B: Well-developed respiratory system. Acoelomates, such as those in Phylum Platyhelminthes, lack a…

• A. Coelom
• B. Gastrocoel
• C. Pseudocoelom
• D. Spongocoel

Explanation: The coelom is a true body cavity that is entirely lined by mesodermal tissue, providing space for the development and suspension of…

• A. Pinworm
• B. Starfish
• C. Cake urchin
• D. Amphioxus

Explanation: Spiral and determinate cleavage is a feature of protostomes, a group that includes organisms such as annelids, mollusks, and nematodes.

• A. Bilaterally symmetrical
• B. Triploblastic metazoan
• C. Dorsoventrally compressed body
• D. Radially symmetrical body

Explanation: The correct answer is 'Radially symmetrical body'. Phylum Platyhelminthes is characterized by bilateral symmetry, meaning there is only…

• A. Flat worms
• B. Roundworms
• C. Segmented worms
• D. None

Explanation: Word Platyhelminthes (derived from the Greek platy, meaning "flat" while helminth meaning "worm") are a phylum of relatively simple…