All Free Biology MCQs with Answers

• A. Littoral
• B. Limnetic
• C. Profundal
• D. Both "a" and "b"

Explanation: It is the open water zone away from the shore and it extends up to the effective light penetration level.

• A. Osmosis
• B. Diffusion
• C. Expansion
• D. Decomposition

Explanation: The swelling of dead bodies in water is primarily due to the process of decomposition.

• A. Social ecology
• B. Synecology
• C. Autoecology
• D. Heteroecology

Explanation: Synecology (or community ecology) refers to the study of groups of organisms in relation to their environment.

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

Explanation: The human gut microbiome includes trillions of commensal bacteria that offer substantial benefits to the host, including aiding digestion…

• A. Cyanobacteria - primary producer
• B. Grasshopper - primary producer
• C. Fungi - Decomposer
• D. Zooplankton - secondary consumer

Explanation: Zooplankton is a primary consumer NOT a secondary consumer.

• A. Foliose lichens
• B. Crustose lichens
• C. Fruticose lichens
• D. Climax stage

Explanation: Due to great exposure to the sun and extreme deficiency of water, the first pioneers in the bare rock area are a few simple organisms.

• A. Always unidirectional
• B. Always bidirectional
• C. In any direction
• D. Always down directional

Explanation: In an ecosystem, energy flows in a unidirectional manner, primarily from producers (such as plants) to consumers (such as herbivores…

• A. Density
• B. Natality
• C. Mortality
• D. Dispersion

Explanation: Natality refers to the rate at which new individuals are added to a population in a unit of time. It is also known as birth rate.

• A. Sand
• B. Water
• C. Forest floor
• D. Bare rocks

Explanation: Lithosere is a specific type of ecological succession that occurs on bare rocks.

• A. Respiration and reproduction
• B. Reproduction and nourishment
• C. Strong of wase products
• D. Respiration and storage of waste products

Explanation: During the development of chick and other vertebrates, there are produced certain tissues or structures that temporarily or permanently do…

• A. Pincer cells
• B. Blastomers
• C. Nephrotome
• D. Parietal

Explanation: Pincer cells are deformed blood cells which are a characteristic feature of hereditary spherocytosis associated with Protein Band-3…

• A. Orgenogenesis
• B. Blastula
• C. Gastrula
• D. Development

Explanation: Zygote develops by a sequence of mitotic division, called cleavage, into a multicellular structure, first a solid ball of cells the…

• A. Cleft palate
• B. Polydactyly
• C. Hard-palate
• D. Microcephaly

Explanation: A cleft palate is a congenital condition often associated with a hare lip, involving an opening or split in the upper lip and/or roof of…

• A. Pericardial fluid
• B. Allantoic fluid
• C. Amniotic fluid
• D. All of these

Explanation: Amniotic fluid plays a crucial role in protecting the developing embryo/fetus against physical trauma.

• A. It occurs only in zygote
• B. It occurs in all body cells
• C. It results in haploid cells only
• D. It results in identical cells

Explanation: Cytokinesis during cleavage results in identical cells as the parent cell divides into two daughter cells.

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

Explanation: Embryonic membranes like the amnion and chorion first appeared in reptiles, making option B the correct answer.

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

Explanation: During embryonic development, the digestive system originates from the endoderm, which is one of the three primary germinal layers.

• A. Area pellucida
• B. Area opaca
• C. Notochord
• D. Primitive streak

Explanation: During the development of a chick embryo, the peripheral part of the blastoderm that remains attached and unseparated from the yolk forms…

• A. Fish
• B. Amphibian
• C. Reptiles
• D. None

Explanation: Extra embryonic membranes like amnion and chorion appeared for the first time in reptiles.

• A. Muscles
• B. Liver
• C. Gonads
• D. Blood vessels

Explanation: GERM LAYERS: A germ layer is a group of cells in an embryo. There are 3 germ layers: the endoderm (inner layer), the ectoderm (outer…