All Free Biology MCQs with Answers

• A. Community
• B. Ecosystem
• C. Biosphere
• D. Microhabitat

Explanation: A community is a group of interacting species, which live in the same location.

• A. Lithosphere
• B. Hydrosphere
• C. Community
• D. Biosphere

Explanation: The biosphere is the part of an ecosystem which integrates all living organisms and their relationship with one another.

• A. Commensalism
• B. Parasitism
• C. Mutualism
• D. Predation

Explanation: A symbiotic relationship, or symbiosis, is a close and long-term biological interaction between two different species.

• A. Primary successions
• B. Secondary successions
• C. Seres
• D. Xeroses

Explanation: The term specifically used for each individual succession in animal or plant is called seres. Therefore this is the right option here.

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

Explanation: The given statement is the definition of Niche given by Grinnell. Therefore opt A is the right choice here.

• A. T1
• B. T2
• C. T3
• D. T4

Explanation: Herbivores which are the primary consumers belong to trophic level 2.

• A. 5
• B. 3
• C. 6
• D. 4

Explanation: A series of organisms each dependent on the next as a source of food is called a food chain.

• A. Mutualism
• B. Commensalism
• C. Predation
• D. Parasitism

Explanation: The relationship in which one organism gets benefit and the other is not affected is called commensalism.

• A. Lichens
• B. Shrubs
• C. Moss
• D. Herbs

Explanation: Lichens: This option is the correct answer. Lichens are the first organisms that typically colonize and establish on bare rock during…

• A. 1
• B. 3
• C. 4
• D. 2

Explanation: D option is the correct answer. The trophic level of a herbivore is generally at the second level.

• A. Primary consumer
• B. Primary producer
• C. Tertiary consumer
• D. Secondary consumer

Explanation: Secondary consumers belong to trophic level three, they feed on primary consumers.

• A. Photosynthesis
• B. Sun
• C. Plants
• D. Water

Explanation: Sun is the ultimate source of energy because it is the source of most of the energies on Earth.

• A. Detritus
• B. Herbivores
• C. Green plants
• D. Omnivores

Explanation: The living part of the food chain always begins with plant life, as plants are the only organisms that get their energy from a nonliving…

• A. Pioneers
• B. Xerosere
• C. Succession
• D. Secondary succession

Explanation: A broad definition of succession states: 'Ecological succession is the process by which the mix of species and habitat in an area changes…

• A. Bacterial reduction of NO3- ions to N2 gas.
• B. Active uptake of Nitrate ions by plant roots
• C. Drainage of manure from fields
• D. Leaching of nitrate ions

Explanation: Denitrification is a natural soil microbial process where nitrate ions are converted to nitrogen gas which is then lost to the atmosphere.

• A. Nutritional Cause
• B. Hormonal Causes
• C. Skeleton Damage
• D. Genetic Defect

Explanation: Explanation: Microcephaly, the small-sized skull, is usually due to a genetic defect.

• A. Hensen's Node
• B. Primitive Ridge
• C. Gastrocoel
• D. Primitive Gut

Explanation: Explanation:At the cephalic end of the primitive streak, closely packed cells form a locai thickening known as Hensen's node.

• A. Muscle cells
• B. Gut
• C. Notochord and neural tube
• D. Larval epidermis

Explanation: [A]Sarcoplasm is the cytoplasm of muscle cell which is yellow in colour[B] Gut is produced by grey vegetal cytoplasm[C] Notochord and…

• A. Mesoderm
• B. Ectoderm
• C. Endoderm
• D. Mesoderm and Endoderm

Explanation: Option [A]Mesoderm gives rise to muscular,skeletal and reproductive systemsOption [B] After embryonic development the body layers[…

• A. Non-competitive
• B. Competitive
• C. Irreversible
• D. Isosteric

Explanation: In noncompetitive inhibition, the inhibitor binds at an allosteric site separate from the active site of substrate binding.