Preparing for board exams becomes easier when students practice well-structured and accurate questions. This article provides Class 12 Biology MCQs with Answers to help learners strengthen their understanding of important concepts such as genetics, human physiology, ecology, evolution, plant physiology, and biotechnology. These multiple-choice questions are designed to match the latest exam pattern and improve problem-solving skills. By reviewing these MCQs along with their correct answers, students can quickly revise key chapters, assess their knowledge, and boost their confidence for competitive exams and final board exams. Start practicing these biology mcqs now to score high in Biology.
Class 12 Biology MCQs with Answers
Q1. The genetic material in most viruses is:
A) DNA
B) RNA
C) Either DNA or RNA
D) Protein
Answer: C) Either DNA or RNA
Q2. Mendel’s law of independent assortment applies to:
A) Genes on the same chromosome
B) Genes on different chromosomes
C) Only dominant traits
D) Only recessive traits
Answer: B) Genes on different chromosomes
Q3. In a dihybrid cross of AaBb × AaBb, the expected phenotypic ratio is:
A) 9:3:3:1
B) 3:1
C) 1:2:1
D) 1:1:1:1
Answer: A) 9:3:3:1
Q4. A plasmid used in genetic engineering is:
A) Linear DNA
B) Circular DNA
C) RNA molecule
D) Protein molecule
Answer: B) Circular DNA
Q5. Polymerase Chain Reaction (PCR) is used to:
A) Amplify DNA
B) Transcribe RNA
C) Translate protein
D) Cut DNA
Answer: A) Amplify DNA
Q6. Restriction enzymes are used to:
A) Join DNA fragments
B) Cut DNA at specific sequences
C) Amplify DNA
D) Synthesize RNA
Answer: B) Cut DNA at specific sequences
Q7. Which of the following is a vector used in gene cloning?
A) Bacteriophage
B) Plasmid
C) Cosmid
D) All of the above
Answer: D) All of the above
Q8. RNA interference is used to:
A) Suppress gene expression
B) Amplify DNA
C) Increase protein synthesis
D) Replicate RNA viruses
Answer: A) Suppress gene expression
Q9. Which hormone initiates seed germination?
A) Auxin
B) Gibberellin
C) Cytokinin
D) Ethylene
Answer: B) Gibberellin
Q10. Bt cotton is genetically modified to resist:
A) Fungi
B) Insects
C) Viruses
D) Drought
Answer: B) Insects
Q11. The functional unit of kidney is:
A) Neuron
B) Nephron
C) Glomerulus
D) Tubule
Answer: B) Nephron
Q12. Which hormone regulates blood calcium levels?
A) Insulin
B) Parathormone
C) Thyroxine
D) Cortisol
Answer: B) Parathormone
Q13. The pacemaker of the heart is:
A) AV node
B) SA node
C) Bundle of His
D) Purkinje fibers
Answer: B) SA node
Q14. Which blood cells are involved in immunity?
A) RBC
B) WBC
C) Platelets
D) Plasma proteins
Answer: B) WBC
Q15. Oxygen transport in blood is primarily by:
A) Plasma
B) Hemoglobin
C) Platelets
D) WBC
Answer: B) Hemoglobin
Q16. The hormone responsible for fight-or-flight response:
- A) Cortisol
B) Adrenaline
C) Thyroxine
D) Insulin
Answer: B) Adrenaline
Q17. The enzyme responsible for starch digestion in humans:
A) Pepsin
B) Amylase
C) Lipase
D) Trypsin
Answer: B) Amylase
Q18. Which organ stores bile?
A) Liver
B) Gall bladder
C) Pancreas
D) Stomach
Answer: B) Gall bladder
Q19. Insulin is secreted by:
A) Alpha cells
B) Beta cells
C) Delta cells
D) Acinar cells
Answer: B) Beta cells
Q20. RBCs lack:
A) Nucleus
B) Cytoplasm
C) Hemoglobin
D) Cell membrane
Answer: A) Nucleus
Q21. The genetic material in most viruses is:
A) DNA
B) RNA
C) Either DNA or RNA
D) Protein
Answer: C) Either DNA or RNA
Q22. Mendel’s law of independent assortment applies to:
A) Genes on the same chromosome
B) Genes on different chromosomes
C) Only dominant traits
D) Only recessive traits
Answer: B) Genes on different chromosomes
Q23. In a dihybrid cross of AaBb × AaBb, the expected phenotypic ratio is:
A) 9:3:3:1
B) 3:1
C) 1:2:1
D) 1:1:1:1
Answer: A) 9:3:3:1
Q24. A plasmid used in genetic engineering is:
A) Linear DNA
B) Circular DNA
C) RNA molecule
D) Protein molecule
Answer: B) Circular DNA
Q25. Polymerase Chain Reaction (PCR) is used to:
A) Amplify DNA
B) Transcribe RNA
C) Translate protein
D) Cut DNA
Answer: A) Amplify DNA
Q26. Restriction enzymes are used to:
A) Join DNA fragments
B) Cut DNA at specific sequences
C) Amplify DNA
D) Synthesize RNA
Answer: B) Cut DNA at specific sequences
Q27. Which of the following is a vector used in gene cloning?
A) Bacteriophage
B) Plasmid
C) Cosmid
D) All of the above
Answer: D) All of the above
Q28. RNA interference is used to:
A) Suppress gene expression
B) Amplify DNA
C) Increase protein synthesis
D) Replicate RNA viruses
Answer: A) Suppress gene expression
Q29. Which hormone initiates seed germination?
A) Auxin
B) Gibberellin
C) Cytokinin
D) Ethylene
Answer: B) Gibberellin
Q30. Bt cotton is genetically modified to resist:
A) Fungi
B) Insects
C) Viruses
D) Drought
Answer: B) Insects
Q31. Transgenic plants are produced by:
A) Cross-pollination
B) Gene transfer
C) Budding
D) Grafting
Answer: B) Gene transfer
Q32. Which type of RNA carries amino acids to ribosomes?
A) mRNA
B) rRNA
C) tRNA
D) snRNA
Answer: C) tRNA
Q33. Gene cloning is important because it helps in:
A) Producing insulin
B) Producing antibodies
C) Developing GM crops
D) All of the above
Answer: D) All of the above
Q34. Which enzyme converts RNA to DNA in retroviruses?
A) Reverse transcriptase
B) DNA polymerase
C) RNA polymerase
D) Ligase
Answer: A) Reverse transcriptase
Q35. Golden rice is enriched with:
A) Vitamin C
B) Vitamin A
C) Vitamin D
D) Vitamin B12
Answer: B) Vitamin A
Q36. The functional unit of kidney is:
A) Neuron
B) Nephron
C) Glomerulus
D) Tubule
Answer: B) Nephron
Q37. Which hormone regulates blood calcium levels?
A) Insulin
B) Parathormone
C) Thyroxine
D) Cortisol
Answer: B) Parathormone
Q38. The pacemaker of the heart is:
A) AV node
B) SA node
C) Bundle of His
D) Purkinje fibers
Answer: B) SA node
Q39. Which blood cells are involved in immunity?
A) RBC
B) WBC
C) Platelets
D) Plasma proteins
Answer: B) WBC
Q40. Oxygen transport in blood is primarily by:
A) Plasma
B) Hemoglobin
C) Platelets
D) WBC
Answer: B) Hemoglobin
Q42. The hormone responsible for fight-or-flight response:
A) Cortisol
B) Adrenaline
C) Thyroxine
D) Insulin
Answer: B) Adrenaline
Q43. The enzyme responsible for starch digestion in humans:
A) Pepsin
B) Amylase
C) Lipase
D) Trypsin
Answer: B) Amylase
Q44. Which organ stores bile?
A) Liver
B) Gall bladder
C) Pancreas
D) Stomach
Answer: B) Gall bladder
Q45. Insulin is secreted by:
A) Alpha cells
B) Beta cells
C) Delta cells
D) Acinar cells
Answer: B) Beta cells
Q46. RBCs lack:
A) Nucleus
B) Cytoplasm
C) Hemoglobin
D) Cell membrane
Answer: A) Nucleus
Q47. The site of aerobic respiration in cells:
A) Cytoplasm
B) Nucleus
C) Mitochondria
D) Ribosome
Answer: C) Mitochondria
Q48. Which of the following is part of the endocrine system?
A) Thyroid
B) Heart
C) Lungs
D) Kidney
Answer: A) Thyroid
Q49. Deficiency of which vitamin causes rickets?
A) Vitamin A
B) Vitamin C
C) Vitamin D
D) Vitamin K
Answer: C) Vitamin D
Q50. Which part of the brain controls balance?
A) Cerebrum
B) Cerebellum
C) Medulla oblongata
D) Hypothalamus
Answer: B) Cerebellum
Q51. The functional unit of nervous system is:
A) Axon
B) Neuron
C) Dendrite
D) Synapse
Answer: B) Neuron
Q52. The hormone responsible for cell elongation in plants is:
A) Cytokinin
B) Auxin
C) Gibberellin
D) Ethylene
Answer: B) Auxin
Q53. Photosynthesis primarily occurs in:
A) Roots
B) Stems
C) Leaves
D) Flowers
Answer: C) Leaves
Q54. Xylem transports:
A) Water and minerals
B) Food
C) Hormones
D) Enzymes
Answer: A) Water and minerals
Q55. Phloem transports:
A) Water
B) Minerals
C) Food (sucrose)
D) Oxygen
Answer: C) Food (sucrose)
Q56. The process of opening and closing of stomata is controlled by:
A) Auxin
B) Guard cells
C) Xylem
D) Phloem
Answer: B) Guard cells
Q57. The primary pigment involved in photosynthesis is:
A) Carotene
B) Xanthophyll
C) Chlorophyll
D) Anthocyanin
Answer: C) Chlorophyll
Q58. The plant hormone that promotes seed germination is:
A) Gibberellin
B) Auxin
C) Cytokinin
D) ABA
Answer: A) Gibberellin
Q59. Which part of the plant is responsible for transpiration?
A) Stomata
B) Xylem
C) Phloem
D) Roots
Answer: A) Stomata
Q60. Photoperiodism in plants refers to:
A) Flowering response to temperature
B) Flowering response to day length
C) Seed germination
D) Leaf fall
Answer: B) Flowering response to day length
Q61. Abscisic acid (ABA) is responsible for:
A) Promoting seed dormancy
B) Promoting growth
C) Flowering
D) Fruit ripening
Answer: A) Promoting seed dormancy
Q62. Fertilization in humans occurs in:
A) Ovary
B) Uterus
C) Fallopian tube
D) Cervix
Answer: C) Fallopian tube
Q63. The male gamete in plants is produced in:
A) Ovule
B) Anther
C) Pistil
D) Sepal
Answer: B) Anther
Q64. Placenta in humans functions for:
A) Excretion
B) Nutrition and gas exchange
C) Hormone secretion
D) All of the above
Answer: D) All of the above
Q65. Spermatogenesis occurs in:
A) Ovary
B) Testis
C) Epididymis
D) Vas deferens
Answer: B) Testis
Q66. Oogenesis results in:
A) One egg and polar bodies
B) Two eggs
C) Three eggs
D) Four eggs
Answer: A) One egg and polar bodies
Q67. The fusion of male and female gametes is called:
A) Pollination
B) Fertilization
C) Germination
D) Meiosis
Answer: B) Fertilization
Q68. In flowering plants, double fertilization produces:
A) Embryo only
B) Endosperm only
C) Embryo and endosperm
D) Seed coat
Answer: C) Embryo and endosperm
Q69. The hormone responsible for uterine contraction during childbirth is:
A) Progesterone
B) Oxytocin
C) Prolactin
D) Estrogen
Answer: B) Oxytocin
Q70. Secondary sexual characteristics in males are developed under:
A) Estrogen
B) Testosterone
C) Progesterone
D) FSH
Answer: B) Testosterone
Q71. The period of development from fertilization to birth is called:
A) Embryonic period
B) Gestation
C) Menstrual cycle
D) Lactation
Answer: B) Gestation
Q72. The primary producers in an ecosystem are:
A) Herbivores
B) Carnivores
C) Plants
D) Decomposers
Answer: C) Plants
Q73. The ultimate source of energy for all ecosystems is:
A) Sun
B) Soil
C) Water
D) Air
Answer: A) Sun
Q74. Nitrogen fixation is carried out by:
A) Cyanobacteria
B) Fungi
C) Earthworms
D) Algae
Answer: A) Cyanobacteria
Q75. The study of interactions among organisms and their environment is:
A) Zoology
B) Botany
C) Ecology
D) Genetics
Answer: C) Ecology
Q76. Biomagnification refers to:
A) Increase of toxin concentration up the food chain
B) Decomposition of biomass
C) Photosynthesis
D) Energy loss in ecosystem
Answer: A) Increase of toxin concentration up the food chain
Q77. Eutrophication is caused due to:
A) Deforestation
B) Excess nutrients in water
C) Air pollution
D) Soil erosion
Answer: B) Excess nutrients in water
Q78. The carbon cycle is essential because:
A) Plants get carbon dioxide for photosynthesis
B) Animals get carbon for respiration
C) Maintains ecological balance
D) All of the above
Answer: D) All of the above
Q79. The layer of Earth where organisms live is called:
A) Lithosphere
B) Biosphere
C) Atmosphere
D) Hydrosphere
Answer: B) Biosphere
Q80. A keystone species is:
A) Dominant predator that maintains ecosystem balance
B) Plant species only
C) Parasite species
D) Any common species
Answer: A) Dominant predator that maintains ecosystem balance
Conclusion
Practicing Class 12 Biology MCQs with Answers is one of the most effective ways to revise important concepts and improve exam performance. These questions help students understand key topics, identify weak areas, and enhance their accuracy and speed. With consistent practice, students become more confident in tackling both board exams and competitive exams. These biology MCQ will be helpful as a quick revision tool to strengthen your fundamentals and ensure better preparedness. Keep practicing, stay focused, and you will be well on your way to scoring excellent marks in Biology.
