All Free Biology MCQs with Answers

• A. Marsupials
• B. Eutherians
• C. Monotremes
• D. Metatherians

Explanation: Monotremes are considered the connecting link between reptiles and mammals because they exhibit both reptilian features, such as laying…

• A. Clam worm
• B. Silver Fish
• C. Leach
• D. Spider

Explanation: book lung, form of respiratory organ found in certain air-breathing arachnid arthropods (scorpions and some spiders).

• A. Parazoa
• B. Metazoa
• C. Sporozoa
• D. Monera

Explanation: The correct answer is Sporozoa. Protozoa are unicellular organisms that lack tissue level organization, while Sporozoa specifically…

• A. Insecta
• B. Annelida
• C. Crustacean
• D. Arachinda

Explanation: Crustacean: This is the correct option. Daphnia belongs to the class Crustacea within the phylum Arthropoda.

• A. Sudoriferous glands
• B. Endocrine glands
• C. Preen gland
• D. Thymus glands

Explanation: The correct answer is the preen gland. Birds use the preen oil secreted by the uropygial gland to waterproof their feathers.

• A. Sponge
• B. Leech
• C. Salamander
• D. Grasshopper

Explanation: The correct answer is Sponge. Sponges have a sedentary adult stage where they are attached to a substratum, while their larval stages…

• A. Bony Fishes
• B. Shark
• C. Carp
• D. Paramecium

Explanation: Sharks are isotonic with sea water, meaning their body fluids have the same concentration of dissolved substances as the water.

• A. Whale
• B. Bat
• C. Camel
• D. Giraffe

Explanation: In most mammals, sperm is capable of fertilizing eggs for only a few days after copulation.

• A. Metatheria
• B. Eutheria
• C. Theria
• D. Prototheria

Explanation: Metatheria: Opossum belongs to the Metatheria, also known as marsupials.

• A. Earth worm
• B. Sponges
• C. Snakes
• D. Grass Hopper

Explanation: Metamerism is the repetition of homologous body segments. This type of development can be seen in the Annelids, which include earthworms…

• A. Nematodes
• B. Coelenterates
• C. Annelids
• D. Sponges

Explanation: Nematocysts are specialized structures found in coelenterates, which are multicellular aquatic animals living in colonies.

• A. middle ear
• B. internal ear
• C. gills
• D. fins

Explanation: Middle ear: Fish do not possess a middle ear like mammals. Instead, they have a unique structure called the swim bladder, which is used…

• A. Lizard
• B. Turtle
• C. Crocodile
• D. Frog

Explanation: Crocodiles are one of the few reptiles that have a four-chambered heart, similar to that of birds and mammals.

• A. Ascaris
• B. Pinworm
• C. Planaria
• D. Tapeworm

Explanation: Tapeworms are parasitic flatworms, they do not possess an alimentary canal.

• A. Sponge
• B. Leech
• C. Salamander
• D. Grasshopper

Explanation: Sponges are animals that belong to the phylum Porifera. They have a sedentary or sessile lifestyle in their adult stage and are active in…

• A. Amphioxus
• B. Sea horse
• C. Cheatopterus
• D. Sea cucumber

Explanation: Cheatopterus is a genus of trilobite, which is a group of extinct arthropods.

• A. Clam worm
• B. Spider
• C. Silverfish
• D. Leech

Explanation: Book lungs are respiratory organs found in certain arachnids, such as spiders.

• A. Spring sleep
• B. Winter Sleep
• C. Autumn sleep
• D. Summer sleep

Explanation: Aestivation is a term used to describe a state of inactivity or dormancy that certain animals enter during hot or dry periods, typically…

• A. Penguin
• B. Ostrich
• C. Hawk
• D. Kiwi

Explanation: Penguins are swimming birds. They are highly adapted to aquatic life and are known for their ability to swim and drive in the ocean.

• A. Acaelomate
• B. ceolomates
• C. Pseudocoelomates
• D. Deuterostomes

Explanation: A pseudocoelomate is an organism with a body cavity called a pseudocoelem that is not derived from the mesoderm, as in a true coelom, or…