Practice the most important Biology MCQ Questions with Answers for SSC, Railway, Banking, Police, Defence and other competitive exams. These carefully selected multiple choice questions cover Cell, Human Body, Plant Biology, Nutrition, Diseases, Genetics, Ecology and other important Biology topics. Every question includes four options, the correct answer and a brief explanation for quick revision.
Q1. The basic structural and functional unit of life is:
A. Tissue
B. Organ
C. Cell
D. Organism
View Answer
The cell is the basic structural and functional unit of all living organisms.
Q2. Who is known as the Father of Biology?
A. Aristotle
B. Charles Darwin
C. Gregor Mendel
D. Carl Linnaeus
View Answer
Aristotle is regarded as the Father of Biology because of his pioneering work in the study of living organisms.
Q3. Who discovered the cell?
A. Robert Hooke
B. Antonie van Leeuwenhoek
C. Louis Pasteur
D. Robert Koch
View Answer
Robert Hooke discovered cells in 1665 while observing a thin slice of cork under a microscope.
Q4. Which organelle is known as the ‘Powerhouse of the Cell’?
A. Nucleus
B. Ribosome
C. Mitochondria
D. Golgi Body
View Answer
Mitochondria produce ATP through cellular respiration and are called the powerhouse of the cell.
Q5. Which organelle controls all activities of the cell?
A. Lysosome
B. Nucleus
C. Vacuole
D. Chloroplast
View Answer
The nucleus contains genetic material and controls all cellular activities.
Q6. Which organelle is called the ‘Kitchen of the Cell’?
A. Mitochondria
B. Chloroplast
C. Ribosome
D. Golgi Apparatus
View Answer
Chloroplasts prepare food through photosynthesis and are therefore called the kitchen of plant cells.
Q7. Which organelle is known as the ‘Suicide Bag of the Cell’?
A. Ribosome
B. Lysosome
C. Vacuole
D. Centrosome
View Answer
Lysosomes contain digestive enzymes that can break down worn-out cell components.
Q8. Photosynthesis takes place in:
A. Mitochondria
B. Chloroplast
C. Nucleus
D. Ribosome
View Answer
Chloroplasts contain chlorophyll, which captures sunlight for photosynthesis.
Q9. The green pigment present in plants is:
A. Haemoglobin
B. Chlorophyll
C. Melanin
D. Carotene
View Answer
Chlorophyll absorbs sunlight and enables plants to prepare food.
Q10. Plants prepare food by the process of:
A. Respiration
B. Digestion
C. Photosynthesis
D. Transpiration
View Answer
Photosynthesis uses sunlight, water and carbon dioxide to produce glucose and oxygen.
Q11. Which gas is released during photosynthesis?
A. Nitrogen
B. Oxygen
C. Carbon Dioxide
D. Hydrogen
View Answer
Oxygen is released as a by-product during photosynthesis.
Q12. Which gas is absorbed by plants during photosynthesis?
A. Oxygen
B. Hydrogen
C. Carbon Dioxide
D. Nitrogen
View Answer
Plants absorb carbon dioxide from the atmosphere to prepare food.
Q13. The study of plants is called:
A. Zoology
B. Botany
C. Ecology
D. Genetics
View Answer
Botany is the branch of biology that deals with the study of plants.
Q14. The study of animals is called:
A. Botany
B. Genetics
C. Zoology
D. Microbiology
View Answer
Zoology is the scientific study of animals.
Q15. Which tissue transports water in plants?
A. Phloem
B. Xylem
C. Epidermis
D. Cortex
View Answer
Xylem transports water and minerals from the roots to other parts of the plant.
Q16. Which tissue transports food in plants?
A. Xylem
B. Phloem
C. Cambium
D. Epidermis
View Answer
Phloem carries food prepared in the leaves to different parts of the plant.
Q17. The largest organ in the human body is:
A. Liver
B. Brain
C. Skin
D. Heart
View Answer
Skin is the largest organ of the human body and protects internal organs.
Q18. The largest internal organ of the human body is:
A. Kidney
B. Liver
C. Lungs
D. Stomach
View Answer
The liver is the largest internal organ and performs numerous metabolic functions.
Q19. The smallest bone in the human body is:
A. Femur
B. Tibia
C. Stapes
D. Fibula
View Answer
The stapes, located in the middle ear, is the smallest bone in the human body.
Q20. The longest bone in the human body is:
A. Humerus
B. Radius
C. Femur
D. Tibia
View Answer
The femur (thigh bone) is the longest and strongest bone in the human body.
Q21. How many chambers are there in the human heart?
A. 2
B. 3
C. 4
D. 5
View Answer
The human heart has four chambers: two atria and two ventricles.
Q22. Which organ pumps blood throughout the human body?
A. Brain
B. Liver
C. Heart
D. Kidney
View Answer
The heart is a muscular organ that pumps blood through the circulatory system.
Q23. Which blood vessel carries oxygenated blood from the heart to the body?
A. Vein
B. Artery
C. Capillary
D. Venule
View Answer
Arteries generally carry oxygen-rich blood away from the heart, except the pulmonary artery.
Q24. Which blood vessel carries blood towards the heart?
A. Artery
B. Vein
C. Capillary
D. Aorta
View Answer
Veins carry blood back to the heart. Most veins carry deoxygenated blood except the pulmonary vein.
Q25. Which is the largest artery in the human body?
A. Pulmonary Artery
B. Aorta
C. Carotid Artery
D. Coronary Artery
View Answer
The aorta is the main artery that carries oxygenated blood from the left ventricle.
Q26. Which blood group is known as the universal donor?
A. A
B. B
C. AB
D. O Negative
View Answer
O negative blood can be transfused to people of all blood groups in emergencies.
Q27. Which blood group is known as the universal recipient?
A. A Positive
B. B Positive
C. AB Positive
D. O Positive
View Answer
AB positive individuals can receive blood from all blood groups.
Q28. Which blood cells help in fighting infections?
A. Red Blood Cells
B. White Blood Cells
C. Platelets
D. Plasma
View Answer
White blood cells protect the body against infections and diseases.
Q29. Which blood cells transport oxygen?
A. White Blood Cells
B. Platelets
C. Red Blood Cells
D. Plasma
View Answer
Red blood cells contain haemoglobin, which transports oxygen throughout the body.
Q30. Which blood component helps in blood clotting?
A. Plasma
B. Platelets
C. RBCs
D. WBCs
View Answer
Platelets help stop bleeding by forming blood clots at the site of injury.
Q31. Haemoglobin contains which metal?
A. Copper
B. Iron
C. Calcium
D. Magnesium
View Answer
Iron is an essential component of haemoglobin, enabling oxygen transport.
Q32. Which organ is primarily responsible for purification of blood?
A. Liver
B. Heart
C. Kidney
D. Lungs
View Answer
The kidneys filter waste products and excess water from the blood.
Q33. Humans normally have how many kidneys?
A. One
B. Two
C. Three
D. Four
View Answer
Healthy humans normally have two kidneys located on either side of the spine.
Q34. Which organ produces bile?
A. Pancreas
B. Liver
C. Gallbladder
D. Stomach
View Answer
The liver produces bile, which helps in the digestion of fats.
Q35. Bile is stored in the:
A. Pancreas
B. Gallbladder
C. Stomach
D. Small Intestine
View Answer
The gallbladder stores and concentrates bile produced by the liver.
Q36. Which organ secretes insulin?
A. Liver
B. Pancreas
C. Kidney
D. Thyroid
View Answer
The pancreas secretes insulin, which helps regulate blood sugar levels.
Q37. Which disease is caused by deficiency of insulin?
A. Tuberculosis
B. Diabetes Mellitus
C. Malaria
D. Cholera
View Answer
Diabetes occurs when the body produces insufficient insulin or cannot use it effectively.
Q38. Which organ is mainly responsible for digestion?
A. Heart
B. Stomach
C. Brain
D. Lungs
View Answer
The stomach plays a major role in digestion by secreting gastric juice and enzymes.
Q39. Most absorption of digested food takes place in the:
A. Large Intestine
B. Small Intestine
C. Stomach
D. Oesophagus
View Answer
The small intestine is the main site for digestion and absorption of nutrients.
Q40. Which is the longest part of the alimentary canal?
A. Oesophagus
B. Stomach
C. Small Intestine
D. Large Intestine
View Answer
The small intestine is about 6 metres long and is the longest part of the digestive system.
Q41. Which organ is the main organ of respiration in humans?
A. Heart
B. Liver
C. Lungs
D. Kidney
View Answer
The lungs exchange oxygen and carbon dioxide between the body and the atmosphere.
Q42. The functional unit of the kidney is:
A. Neuron
B. Nephron
C. Alveolus
D. Villus
View Answer
The nephron filters blood and forms urine. Each kidney contains about one million nephrons.
Q43. The functional unit of the lung is:
A. Alveolus
B. Nephron
C. Villus
D. Axon
View Answer
Alveoli are tiny air sacs where the exchange of oxygen and carbon dioxide takes place.
Q44. The largest gland in the human body is:
A. Pancreas
B. Thyroid
C. Liver
D. Pituitary
View Answer
The liver is the largest gland and performs many metabolic and detoxification functions.
Q45. The largest endocrine gland in the human body is:
A. Thyroid
B. Pituitary
C. Adrenal
D. Pineal
View Answer
The thyroid gland is the largest endocrine gland and produces thyroxine.
Q46. Which gland is known as the ‘Master Gland’?
A. Thyroid
B. Pituitary
C. Adrenal
D. Pancreas
View Answer
The pituitary gland controls the activity of many other endocrine glands.
Q47. Which hormone regulates blood sugar levels?
A. Thyroxine
B. Adrenaline
C. Insulin
D. Estrogen
View Answer
Insulin helps lower blood glucose levels by promoting its uptake into cells.
Q48. Deficiency of iodine causes:
A. Diabetes
B. Goitre
C. Rickets
D. Scurvy
View Answer
Iodine deficiency enlarges the thyroid gland, leading to goitre.
Q49. Which vitamin helps in blood clotting?
A. Vitamin A
B. Vitamin C
C. Vitamin D
D. Vitamin K
View Answer
Vitamin K is essential for the synthesis of clotting factors in the blood.
Q50. Deficiency of Vitamin C causes:
A. Rickets
B. Night Blindness
C. Scurvy
D. Beriberi
View Answer
Scurvy is caused by a deficiency of Vitamin C and results in bleeding gums and poor wound healing.
Q51. Deficiency of Vitamin D causes:
A. Beriberi
B. Rickets
C. Pellagra
D. Anaemia
View Answer
Vitamin D deficiency leads to weak bones and rickets in children.
Q52. Deficiency of Vitamin A causes:
A. Night Blindness
B. Scurvy
C. Beriberi
D. Goitre
View Answer
Vitamin A is essential for vision, especially in dim light.
Q53. Deficiency of Vitamin B₁ causes:
A. Rickets
B. Beriberi
C. Scurvy
D. Pellagra
View Answer
Beriberi is caused by a deficiency of Vitamin B₁ (Thiamine).
Q54. Deficiency of Niacin (Vitamin B₃) causes:
A. Pellagra
B. Beriberi
C. Anaemia
D. Goitre
View Answer
Pellagra is characterized by dermatitis, diarrhoea and dementia.
Q55. Deficiency of iron causes:
A. Diabetes
B. Anaemia
C. Tuberculosis
D. Malaria
View Answer
Iron deficiency reduces haemoglobin production and causes anaemia.
Q56. Which disease is caused by the bite of an infected female Anopheles mosquito?
A. Dengue
B. Malaria
C. Chikungunya
D. Typhoid
View Answer
Malaria is caused by Plasmodium parasites transmitted by female Anopheles mosquitoes.
Q57. Dengue is transmitted by:
A. Housefly
B. Female Anopheles Mosquito
C. Aedes Mosquito
D. Tsetse Fly
View Answer
Dengue virus is spread by the bite of infected Aedes mosquitoes.
Q58. Cholera is caused by:
A. Virus
B. Fungus
C. Bacterium
D. Protozoa
View Answer
Cholera is caused by the bacterium Vibrio cholerae.
Q59. Tuberculosis is caused by:
A. Virus
B. Bacterium
C. Fungus
D. Protozoa
View Answer
Tuberculosis is caused by Mycobacterium tuberculosis.
Q60. AIDS is caused by:
A. Bacteria
B. Virus
C. Fungus
D. Protozoa
View Answer
AIDS is caused by the Human Immunodeficiency Virus (HIV), which attacks the immune system.
Q61. Which disease is caused by a virus?
A. Cholera
B. Tuberculosis
C. Measles
D. Typhoid
View Answer
Measles is a highly contagious viral disease caused by the measles virus.
Q62. Which disease is caused by bacteria?
A. Malaria
B. Typhoid
C. Dengue
D. AIDS
View Answer
Typhoid is caused by the bacterium Salmonella typhi.
Q63. Which disease is caused by a protozoan?
A. Tuberculosis
B. Malaria
C. Cholera
D. Influenza
View Answer
Malaria is caused by the protozoan parasite Plasmodium.
Q64. Which disease is prevented by the BCG vaccine?
A. Polio
B. Tuberculosis
C. Hepatitis B
D. Measles
View Answer
The BCG vaccine provides protection against tuberculosis, especially in children.
Q65. Which vaccine is given to prevent polio?
A. BCG
B. OPV
C. DPT
D. MMR
View Answer
Oral Polio Vaccine (OPV) protects children against poliomyelitis.
Q66. Which vitamin is mainly obtained from sunlight?
A. Vitamin A
B. Vitamin B₁₂
C. Vitamin C
D. Vitamin D
View Answer
The skin synthesizes Vitamin D when exposed to sunlight.
Q67. Which mineral is essential for healthy bones and teeth?
A. Iron
B. Calcium
C. Sodium
D. Potassium
View Answer
Calcium is the primary mineral required for strong bones and teeth.
Q68. Which nutrient is the main source of energy for the human body?
A. Proteins
B. Vitamins
C. Carbohydrates
D. Minerals
View Answer
Carbohydrates are the body’s primary and quickest source of energy.
Q69. Which nutrient is known as the body-building food?
A. Carbohydrates
B. Proteins
C. Fats
D. Vitamins
View Answer
Proteins are essential for growth, repair and maintenance of body tissues.
Q70. Which nutrient provides the maximum energy per gram?
A. Carbohydrates
B. Proteins
C. Fats
D. Minerals
View Answer
Fats provide about 9 kcal of energy per gram, which is more than carbohydrates and proteins.
Q71. Which blood cells are produced in the bone marrow?
A. Red Blood Cells
B. White Blood Cells
C. Platelets
D. All of the Above
View Answer
Bone marrow produces red blood cells, most white blood cells and platelets.
Q72. Which is the largest part of the human brain?
A. Cerebellum
B. Cerebrum
C. Medulla Oblongata
D. Pons
View Answer
The cerebrum controls thinking, memory, intelligence and voluntary actions.
Q73. Which part of the brain controls balance of the body?
A. Cerebrum
B. Cerebellum
C. Medulla
D. Hypothalamus
View Answer
The cerebellum coordinates muscle movements and maintains posture and balance.
Q74. Which organ controls all voluntary activities of the body?
A. Heart
B. Cerebrum
C. Kidney
D. Liver
View Answer
The cerebrum is responsible for conscious thought and voluntary movements.
Q75. The human body has how many pairs of ribs?
A. 10
B. 11
C. 12
D. 13
View Answer
Humans normally have 12 pairs (24) of ribs.
Q76. How many chambers are present in the human heart?
A. 2
B. 3
C. 4
D. 5
View Answer
The human heart has two atria and two ventricles.
Q77. Which is the largest bone in the human body?
A. Tibia
B. Humerus
C. Femur
D. Radius
View Answer
The femur, or thigh bone, is the longest and strongest bone in the human body.
Q78. The normal body temperature of a healthy human is approximately:
A. 35°C
B. 36°C
C. 37°C
D. 39°C
View Answer
The average normal human body temperature is about 37°C (98.6°F).
Q79. Which blood vessel carries oxygenated blood from the lungs to the heart?
A. Pulmonary Artery
B. Pulmonary Vein
C. Aorta
D. Vena Cava
View Answer
The pulmonary vein carries oxygen-rich blood from the lungs to the left atrium of the heart.
Q80. Which blood vessel carries deoxygenated blood from the heart to the lungs?
A. Pulmonary Vein
B. Aorta
C. Pulmonary Artery
D. Coronary Artery
View Answer
The pulmonary artery is the only artery that carries deoxygenated blood from the heart to the lungs for oxygenation.
Q81. Who is known as the Father of Genetics?
A. Charles Darwin
B. Gregor Mendel
C. Louis Pasteur
D. Robert Hooke
View Answer
Gregor Mendel discovered the basic principles of heredity through experiments on pea plants.
Q82. DNA stands for:
A. Deoxyribonucleic Acid
B. Dioxyribonucleic Acid
C. Deoxyribose Nucleic Acid
D. Dynamic Nucleic Acid
View Answer
DNA carries the genetic information responsible for heredity in living organisms.
Q83. RNA stands for:
A. Ribonucleic Acid
B. Ribose Nuclear Acid
C. Reactive Nucleic Acid
D. Ribonitric Acid
View Answer
RNA plays an important role in protein synthesis and gene expression.
Q84. The hereditary unit is called:
A. Chromosome
B. Gene
C. Cell
D. Tissue
View Answer
Genes are the basic units of heredity and are located on chromosomes.
Q85. Humans normally have how many chromosomes?
A. 44
B. 46
C. 48
D. 52
View Answer
Human body cells contain 46 chromosomes arranged in 23 pairs.
Q86. Human beings have how many pairs of chromosomes?
A. 22
B. 23
C. 24
D. 46
View Answer
Humans inherit 23 chromosomes from each parent, making 23 pairs.
Q87. Which blood group is called the universal donor?
A. A+
B. B+
C. AB+
D. O−
View Answer
O negative blood can be donated to individuals of all blood groups in emergencies.
Q88. Which blood group is called the universal recipient?
A. O+
B. A+
C. AB+
D. B−
View Answer
AB positive individuals can receive blood from all ABO and Rh blood groups.
Q89. Which scientist developed the theory of evolution by natural selection?
A. Gregor Mendel
B. Charles Darwin
C. Robert Hooke
D. Louis Pasteur
View Answer
Charles Darwin proposed the theory of evolution through natural selection in his book On the Origin of Species.
Q90. Which scientist developed the first successful vaccine against rabies?
A. Robert Koch
B. Edward Jenner
C. Louis Pasteur
D. Alexander Fleming
View Answer
Louis Pasteur developed the rabies vaccine and made significant contributions to microbiology.
Q91. Who discovered penicillin?
A. Alexander Fleming
B. Edward Jenner
C. Robert Koch
D. Louis Pasteur
View Answer
Alexander Fleming discovered penicillin in 1928, the world’s first antibiotic.
Q92. Who developed the first successful smallpox vaccine?
A. Louis Pasteur
B. Edward Jenner
C. Robert Koch
D. Joseph Lister
View Answer
Edward Jenner is known as the Father of Immunology for developing the smallpox vaccine.
Q93. Which microorganism is used in the preparation of curd?
A. Virus
B. Bacteria
C. Fungus
D. Algae
View Answer
Lactic acid bacteria convert milk into curd by fermentation.
Q94. Which microorganism is used in bread making?
A. Amoeba
B. Yeast
C. Virus
D. Bacteria
View Answer
Yeast ferments sugar and releases carbon dioxide, making bread soft and fluffy.
Q95. Which ecosystem is the largest on Earth?
A. Forest
B. Grassland
C. Ocean
D. Desert
View Answer
Oceans cover about 71% of the Earth’s surface and form the largest ecosystem.
Q96. Which layer of the atmosphere contains the ozone layer?
A. Troposphere
B. Stratosphere
C. Mesosphere
D. Thermosphere
View Answer
The ozone layer in the stratosphere absorbs harmful ultraviolet (UV) radiation from the Sun.
Q97. Which gas is mainly responsible for the greenhouse effect?
A. Oxygen
B. Nitrogen
C. Carbon Dioxide
D. Helium
View Answer
Carbon dioxide is one of the major greenhouse gases contributing to global warming.
Q98. Which process converts atmospheric nitrogen into usable nitrogen compounds?
A. Photosynthesis
B. Nitrogen Fixation
C. Respiration
D. Transpiration
View Answer
Nitrogen-fixing bacteria convert atmospheric nitrogen into compounds that plants can use.
Q99. Which branch of biology deals with the study of microorganisms?
A. Botany
B. Zoology
C. Microbiology
D. Ecology
View Answer
Microbiology is the branch of biology that studies microorganisms such as bacteria, fungi, viruses and protozoa.
Q100. Which branch of biology deals with the relationship between organisms and their environment?
A. Genetics
B. Physiology
C. Ecology
D. Anatomy
View Answer
Ecology studies the interactions between living organisms and their physical environment.
These 100 Biology MCQ Questions with Answers cover the most important topics for SSC, Railway, Banking, Police, Defence and other competitive examinations. The questions include cell biology, human body systems, nutrition, vitamins, diseases, blood, genetics, microorganisms, ecology and environmental science. Regular practice of these MCQs will strengthen your concepts, improve your accuracy and help you score higher in the General Science section of competitive exams.