All Free Biology MCQs with Answers

1721. Which is not a category of classification in biology.

• A. ecotype
• B. Species
• C. Genus
• D. Order

Explanation: Species, genus and order are formal ranks in the taxonomic hierarchy. An ecotype is a genetically adapted population within a species, not a standard taxonomic rank; students may choose species because it is the smallest common rank, but species is definitely a classification category.

1722. Study of impact of extra-terrestrial environments on organisms belonging to earth is component of

• A. Ecology
• B. Cosmology
• C. Exobiology
• D. None of These

Explanation: Exobiology, also called astrobiology, studies life beyond Earth and the effects of extraterrestrial environments on terrestrial organisms or possible life forms. Cosmology deals mainly with the origin and structure of the universe, so it is the likely distractor.

1723. Which of the following animals do not have jaws?

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

Explanation: Protochordates do not possess true jaws, whereas mammals, reptiles and birds are jawed vertebrates. Mammals may be selected because they are familiar vertebrates, but the absence of jaws is associated with primitive chordate groups rather than mammals.

1724. A species inhabiting different geographical areas is known as_________ ?

• A. Hetropatric Specie
• B. Allopatric Specie
• C. Homopatric Specie
• D. Astroparic specie

Explanation: Allopatric populations or species occupy different geographical regions and are separated by a physical barrier or distance. Students may choose heteropatric because it resembles the word in the stem, but “hetropatric” and “astroparic” are not the standard terms used here.

1725. New alleles can be introduced into a population's gene pool by:_________?

• A. Mutation
• B. Natural selection
• C. Gene flow
• D. Both A & C

Explanation: Mutation creates new alleles, while gene flow can introduce alleles from another population. Natural selection changes the frequencies of existing alleles but does not itself create new alleles, so both A and C are correct.

1726. Linnaeus published the list of names of plants in___________?

• A. 1752
• B. 1753
• C. 1754
• D. 1755

Explanation: Linnaeus published Species Plantarum in 1753, establishing a major standard for binomial naming of plants. Students may choose 1752 or 1754 because the surrounding development of his classification system occurred over several years, but the important publication date is 1753.

1727. Coelom is divided into septa in case of:__________?

• A. Molluscs
• B. Annelids
• C. Sponges
• D. Cniderians

Explanation: Annelids have a true coelom divided by transverse septa into repeated compartments, matching their segmented body plan. Molluscs have an unsegmented coelom that is greatly reduced, while sponges and cnidarians do not possess a true coelom, so students may choose molluscs because they also have a coelom.

1728. Study of interaction of living organisms with other organisms and their environment relates with ___________ ?

• A. Botany
• B. Ecology
• C. Social biology
• D. Pharmacology

Explanation: Ecology studies interactions among organisms and between organisms and their physical environment. Botany focuses on plants and pharmacology on drugs, while social biology is not the standard name for this field; students may choose social biology because the stem mentions interactions among living organisms.

1729. The first ever vascular plants are_________?

• A. Cooksonia
• B. Selaginella
• C. Adiantum
• D. Dryopteris

Explanation: Cooksonia is generally regarded as one of the earliest known vascular land plants, appearing in the Silurian Period. Selaginella, Adiantum and Dryopteris are later vascular plants, so students may choose Selaginella because it is also a primitive-looking vascular plant.

1730. Which one of the following is referred as the species occupation?

• A. Autecology
• B. Niche
• C. Ecosystem
• D. Biome

Explanation: A niche is the functional role or occupation of a species, including how it uses resources and interacts with its environment. An ecosystem includes organisms plus their physical environment, while a biome is a large regional ecological unit; students may choose ecosystem because both terms describe organism-environment relationships.