Definition and characters of living organisms MCQs With Answer

Definition and characters of living organisms MCQs With Answer — For B.Pharm students, understanding the definition and characters of living organisms is essential for courses in pharmacology, microbiology and physiology. This concise, keyword-rich introduction reviews cellular organization, metabolism, growth, reproduction, heredity, homeostasis, response to stimuli, adaptation and evolution. The MCQs cover core concepts such as prokaryote vs eukaryote, energy transformations, anabolism vs catabolism, and distinguishing features of life versus viruses, providing application-focused practice for pharmacology contexts. Each question reinforces conceptual clarity and exam readiness with detailed answers. Answers are provided to help self-assess and identify areas for further study. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which statement best defines a living organism?

• An entity that performs metabolism, growth, reproduction and maintains homeostasis
• A structure made only of repeating crystals
• An object that never changes its internal state
• A collection of non-interacting molecules

Correct Answer: An entity that performs metabolism, growth, reproduction and maintains homeostasis

Q2. Which characteristic is common to all living organisms?

• Metabolism
• Photosynthesis
• Mobility
• Chloroplasts

Correct Answer: Metabolism

Q3. What is the smallest structural and functional unit of life?

• Tissue
• Organ
• Cell
• Organism

Correct Answer: Cell

Q4. Why are viruses often not considered fully living?

• They lack cellular organization and independent metabolism
• They can reproduce independently outside hosts
• They perform photosynthesis
• They have complex organ systems

Correct Answer: They lack cellular organization and independent metabolism

Q5. Which feature distinguishes prokaryotes from eukaryotes?

• Presence of membrane-bound nucleus in prokaryotes
• Absence of membrane-bound organelles in prokaryotes
• Multicellularity in all prokaryotes
• Linear chromosomes in prokaryotes

Correct Answer: Absence of membrane-bound organelles in prokaryotes

Q6. A defining characteristic of eukaryotic cells is:

• Membrane-bound organelles such as mitochondria
• Absence of ribosomes
• Single circular chromosome only
• Inability to synthesize proteins

Correct Answer: Membrane-bound organelles such as mitochondria

Q7. Metabolism in living organisms consists of which two broad processes?

• Anabolism and catabolism
• Osmosis and diffusion
• Transcription and translation
• Mutation and selection

Correct Answer: Anabolism and catabolism

Q8. Homeostasis refers to:

• The maintenance of a stable internal environment
• Rapid external morphological change
• Inability to respond to stimuli
• Permanent change in DNA sequence

Correct Answer: The maintenance of a stable internal environment

Q9. Reproduction in living organisms can be broadly classified as:

• Sexual and asexual
• Photosynthetic and chemosynthetic
• Prokaryotic and eukaryotic
• Catabolic and anabolic

Correct Answer: Sexual and asexual

Q10. How does growth differ from development?

• Growth is increase in size or mass; development includes differentiation and maturation
• Growth only occurs in plants; development only in animals
• Growth reduces cellular number; development reduces specialization
• They are identical processes

Correct Answer: Growth is increase in size or mass; development includes differentiation and maturation

Q11. Which molecule is the primary carrier of hereditary information in most living organisms?

• DNA
• Glucose
• ATP
• Lipid

Correct Answer: DNA

Q12. Major sources of genetic variation include:

• Mutation and genetic recombination
• Homeostasis and metabolism
• Osmosis and diffusion
• Respiration and photosynthesis

Correct Answer: Mutation and genetic recombination

Q13. Organisms that synthesize organic molecules from inorganic carbon using light are called:

• Autotrophs
• Heterotrophs
• Parasites
• Saprotrophs

Correct Answer: Autotrophs

Q14. Chemotrophs obtain energy primarily from:

• Oxidation of inorganic or organic chemicals
• Sunlight
• External electrical currents
• Mechanical motion

Correct Answer: Oxidation of inorganic or organic chemicals

Q15. Which process requires molecular oxygen as the final electron acceptor?

• Aerobic respiration
• Fermentation
• Photophosphorylation in some anaerobes
• Substrate-level phosphorylation without O2

Correct Answer: Aerobic respiration

Q16. An example of anaerobic metabolism in many microorganisms is:

• Fermentation
• Oxidative phosphorylation
• Photorespiration
• Beta-oxidation requiring oxygen

Correct Answer: Fermentation

Q17. The main functional property of the plasma membrane is:

• Selective permeability and regulation of substance exchange
• Providing rigid support like a cell wall in all cells
• Storing genetic information
• Generating ribosomes

Correct Answer: Selective permeability and regulation of substance exchange

Q18. Osmoregulation in organisms controls:

• Water and solute balance across membranes
• The rate of transcription only
• Atmospheric pressure around the organism
• External temperature exclusively

Correct Answer: Water and solute balance across membranes

Q19. The ability of an organism to respond to changes in its environment is termed:

• Irritability or responsiveness
• Homeostasis
• Autotrophy
• Catabolism

Correct Answer: Irritability or responsiveness

Q20. Adaptation in biological terms primarily refers to:

• Heritable traits that increase fitness in a given environment
• Short-term acclimatization that is not inherited
• Random movement of molecules
• Immediate behavioral changes only

Correct Answer: Heritable traits that increase fitness in a given environment

Q21. Which of the following is NOT a characteristic of living organisms?

• Crystallization without metabolism
• Reproduction
• Metabolism
• Growth

Correct Answer: Crystallization without metabolism

Q22. Which organism is typically unicellular?

• Yeast (Saccharomyces)
• Human
• Oak tree
• Earthworm

Correct Answer: Yeast (Saccharomyces)

Q23. Cellular differentiation means:

• Cells become specialized in structure and function
• All cells remain identical throughout life
• Cells lose the ability to metabolize
• Cells fuse to form crystals

Correct Answer: Cells become specialized in structure and function

Q24. An emergent property is best described as:

• A new function arising from interactions at a higher level of organization
• A property visible only at the molecular level
• A feature inherent to isolated atoms only
• A reversible chemical bond

Correct Answer: A new function arising from interactions at a higher level of organization

Q25. Saprotrophic organisms obtain nutrients by:

• Decomposing dead organic matter
• Capturing live prey exclusively
• Photosynthesis from sunlight
• Directly converting inorganic minerals to proteins

Correct Answer: Decomposing dead organic matter

Q26. The concept of autopoiesis in biology refers to:

• Self-maintaining and self-producing systems
• Complete dependence on external manufacture
• Immediate death upon damage
• Random assembly of molecules into life

Correct Answer: Self-maintaining and self-producing systems

Q27. Which mode of reproduction typically reduces genetic variation?

• Asexual reproduction
• Sexual reproduction
• Meiosis with crossing over
• Genetic recombination

Correct Answer: Asexual reproduction

Q28. Binary fission is a common reproductive method in:

• Bacteria
• Ferns
• Mammals
• Flowering plants

Correct Answer: Bacteria

Q29. A pluripotent stem cell can:

• Differentiate into many but not all cell types
• Differentiate into only one cell type
• Not divide at all
• Immediately die upon division

Correct Answer: Differentiate into many but not all cell types

Q30. Which organelle is primarily associated with ATP production in eukaryotic cells?

• Mitochondrion
• Ribosome
• Golgi apparatus
• Lysosome

Correct Answer: Mitochondrion

Q31. In plant cells, photosynthesis mainly occurs in the:

• Chloroplast
• Endoplasmic reticulum
• Golgi apparatus
• Lysosome

Correct Answer: Chloroplast

Q32. Which cellular structure is the site of protein synthesis?

• Ribosome
• Peroxisome
• Centrosome
• Cell wall

Correct Answer: Ribosome

Q33. Lysosomes function primarily in:

• Digestion of macromolecules and cellular debris
• Photosynthetic carbon fixation
• Synthesizing DNA
• Conducting nerve impulses

Correct Answer: Digestion of macromolecules and cellular debris

Q34. In eukaryotic cells, DNA replication occurs mainly in the:

• Nucleus
• Cell membrane
• Golgi apparatus
• Vacuole

Correct Answer: Nucleus

Q35. The central dogma of molecular biology describes flow of information as:

• DNA → RNA → Protein
• Protein → RNA → DNA
• RNA → DNA → Protein
• Lipid → Carbohydrate → Protein

Correct Answer: DNA → RNA → Protein

Q36. Which class of viruses stores its genetic information as RNA?

• RNA viruses
• Bacteriophages with DNA only
• Organelles like mitochondria
• Prions

Correct Answer: RNA viruses

Q37. A molecular characteristic important for life is the ability of some molecules to:

• Self-replicate and template information
• Remain chemically inert forever
• Prevent any form of catalysis
• Absorb unlimited heat without change

Correct Answer: Self-replicate and template information

Q38. True growth at the cellular level usually involves:

• Cell division and cell enlargement
• Only increase in water content without biosynthesis
• Immediate loss of DNA
• Complete shutdown of metabolism

Correct Answer: Cell division and cell enlargement

Q39. Which of the following is primarily a catabolic pathway?

• Glycolysis
• Protein synthesis
• DNA replication
• Photosynthetic carbon fixation

Correct Answer: Glycolysis

Q40. An anabolic biological process example is:

• Protein synthesis from amino acids
• Glycogen breakdown
• Lipid oxidation for energy
• RNA degradation

Correct Answer: Protein synthesis from amino acids

Q41. Living organisms maintain low internal entropy by:

• Constant energy input and metabolic work
• Isolating themselves from all energy sources
• Increasing internal disorder without energy use
• Converting energy into mass only

Correct Answer: Constant energy input and metabolic work

Q42. Which statement about metabolism is FALSE?

• Metabolism is unidirectional and cannot be regulated
• Metabolism includes both anabolic and catabolic reactions
• Enzymes regulate metabolic pathways
• Metabolism is essential for growth and maintenance

Correct Answer: Metabolism is unidirectional and cannot be regulated

Q43. The physiological process enabling organisms to regulate internal temperature is:

• Thermoregulation
• Osmosis
• Photosynthesis
• Meiosis

Correct Answer: Thermoregulation

Q44. A hallmark of evolution in populations is:

• Change in allele frequencies over generations
• Immediate transformation of individuals into new species
• Uniform genomes in all members of a species forever
• Instant adaptation without selection

Correct Answer: Change in allele frequencies over generations

Q45. One limitation of the classical cell theory was that it did not account for:

• Acellular entities like viruses
• The existence of cells
• Basic metabolic reactions
• Genetic inheritance

Correct Answer: Acellular entities like viruses

Q46. The typical prokaryotic genome is organized as:

• A single circular DNA molecule
• Multiple linear chromosomes with histones
• Only RNA molecules encoding proteins
• Chromosomes enclosed in a nucleus

Correct Answer: A single circular DNA molecule

Q47. Which hormonal pair is primarily involved in mammalian blood glucose homeostasis?

• Insulin and glucagon
• Thyroxine and adrenaline only
• Estrogen and progesterone
• Aldosterone and renin

Correct Answer: Insulin and glucagon

Q48. Which property most clearly distinguishes living cells from inanimate matter?

• Metabolism with energy transformation and self-maintenance
• Being composed of carbon atoms only
• Having blue color under the microscope
• Remaining chemically unchanged indefinitely

Correct Answer: Metabolism with energy transformation and self-maintenance

Q49. The Golgi apparatus is primarily involved in:

• Modification, sorting and packaging of proteins
• ATP synthesis by oxidative phosphorylation
• Storing genetic information
• Breaking down fatty acids via beta-oxidation

Correct Answer: Modification, sorting and packaging of proteins

Q50. Fecundity in biological terms refers to:

• Reproductive capacity or potential reproductive output
• Ability to maintain constant temperature
• Rate of photosynthetic carbon fixation only
• Capacity to digest cellulose only

Correct Answer: Reproductive capacity or potential reproductive output