All Free Biology MCQs with Answers

• A. All mammals are viviparous
• B. All cyclostomes do not possess jaws and paired fins
• C. All reptiles have a three chambered heart
• D. All pisces have gills covered by an operculum

Explanation: All cyclostomes lack true jaws and paired fins. Cyclostomes are jawless fish characterized by their round, sucker-like mouths for feeding…

• A. Hydra
• B. Obelia
• C. Aurelia
• D. All of these

Explanation: Metagenesis or alternation between polyp and medusa forms is a characteristic feature of phylum cnidaria.

• A. Dugesia
• B. Fasciola
• C. Taenia
• D. All of these

Explanation: Option Ais correct.Yes, Dugesia is a free-living example of Platyhelminthes.

• A. polyps
• B. Medusae
• C. Both A and B
• D. None of these

Explanation: Polyps are sessile, or attached, zooids in cnidarians. They are typically cup-shaped and have tentacles that they use to capture prey.

• A. Excretory system
• B. Digestive system
• C. Circulatory system
• D. Nervous system

Explanation: The circulatory system in annelids is segmentally arranged with segmental vessels distributing blood along the body segments.

• A. The alimentary canal is formed from the endodermal cells
• B. The alimentary canal has a single opening
• C. The alimentary canal is sac-like
• D. All of these

Explanation: All three statements correctly describe the alimentary canal of Hydra.

• A. Tentacles
• B. Palps
• C. Eyes
• D. Both B and C

Explanation: This is correct as polychaetes have sensory palps and they have well developed eyes with photoreceptors.

• A. Pseudocoelom
• B. Enterocoelom
• C. Schizocoelom
• D. Both a and b

Explanation: An enterocoelom is a true coelom that develops from the archenteron during embryonic development.

• A. Separate layer of cells
• B. Structure formed from them
• C. Their function in body
• D. Structure associated with them

Explanation: 3 different structures are formed the 3 layers in triploblast after embryonic developement.

• A. Penguin is homeothermic while the remaining three are poikilothermic
• B. Leech is a freshwater form while all others are marine
• C. Spongilla has special collared cells called choanocytes which are not found in the remaining three
• D. All are bilaterally symmetrical.

Explanation: Spongilla is a common, widely distributed fresh water sponge belonging to phylum porifera.

• A. Diploblastic
• B. Acoelomate
• C. Triploblastic
• D. Pseudocoelomate

Explanation: Grade radiata animals, such as those in the phylum Cnidaria, are diploblastic, meaning they develop from two primary germ layers: the…

• A. Coelomic Epithelium
• B. Ectoderm
• C. Visceral mesoderm
• D. Parietal Mesoderm

Explanation: In coelomates, the mesoderm splits to form the coelom. The visceral layer of mesoderm surrounds the endoderm (gut), while the parietal…

• A. Porifera
• B. Platyhelminthes
• C. Arthropoda
• D. Chordates

Explanation: Platyhelminthes has flat worms. They are triploblastic and have mouth which opens into a gut but no anus so their digestive system is…

• A. Homeothermic
• B. Poikilothermic
• C. Hair
• D. Four chambered heart

Explanation: Hair is a defining characteristic of mammals. Most mammals have hair or fur covering some or all of their bodies.

• A. To increase the size of the animals
• B. To help in the functioning of reproductive system
• C. To provide space for the development of organs and systems
• D. All of these options are correct

Explanation: Coelom is the fluid-filled body cavity of an animal that contains all the organs.

• A. Digestive system
• B. Reproductive system
• C. Respiratory system
• D. Excretory system

Explanation: Flame cells function like the kidney, removing waste materials throug filteration.

• A. Hydra
• B. Obelia
• C. Aurellia
• D. All of these options are correct

Explanation: Hydra does not show alternation of generation in its life cycle. It also does not have any larval stage during its life cycle.

• A. Goat
• B. Whale
• C. Shark
• D. Seal

Explanation: Mammals are a group of warm-blooded animals that give birth to their offspring such that the young are fed with milk produced in their…

• A. Aname
• B. Anemia
• C. Anima
• D. None of these

Explanation: The word animal comes from the Latin word anima or animalis, meaning 'having breath', 'having soul', or 'living being'.

• A. Flatworms
• B. Roundworms
• C. Cnidarians
• D. Chordates

Explanation: Option A: Flatworms, also known as Platyhelminthes, have three germinal layers (ectoderm, mesoderm, and endoderm) but do not possess a…