Biology Practice Questions | Biology MCQs
Test your biology knowledge with these 100 Biology MCQ Practice Questions with answers and explanations. This collection covers important topics such as human anatomy, cells, plants, genetics, diseases, nutrition, ecology, microorganisms, reproduction and basic biology. These biology questions are useful for students, general science practice, competitive exams and quick revision.
Q1. What is the basic structural and functional unit of life?
A. Tissue
B. Organ
C. Cell
D. Nucleus
View Answer
The cell is the basic structural and functional unit of all living organisms.
Q2. Which organelle is known as the powerhouse of the cell?
A. Ribosome
B. Mitochondrion
C. Nucleus
D. Golgi apparatus
View Answer
Mitochondria produce most of the cell’s ATP through cellular respiration and are therefore commonly called the powerhouse of the cell.
Q3. Which part of the human body pumps blood throughout the body?
A. Liver
B. Heart
C. Kidney
D. Lung
View Answer
The heart is a muscular organ that pumps blood through the circulatory system.
Q4. Which pigment gives plants their green colour?
A. Haemoglobin
B. Chlorophyll
C. Melanin
D. Keratin
View Answer
Chlorophyll is the main green pigment in plants and plays a central role in photosynthesis.
Q5. Which organ is primarily responsible for filtering waste products from the blood?
A. Heart
B. Kidney
C. Stomach
D. Pancreas
View Answer
The kidneys filter the blood and remove metabolic wastes by forming urine.
Q6. Which gas is released by green plants during photosynthesis?
A. Carbon dioxide
B. Oxygen
C. Nitrogen
D. Hydrogen
View Answer
Oxygen is released as a by-product of photosynthesis.
Q7. Which blood cells help fight infections?
A. Red blood cells
B. White blood cells
C. Platelets
D. Plasma cells only
View Answer
White blood cells are important components of the immune system and help defend the body against infections.
Q8. Which blood cells carry oxygen?
A. White blood cells
B. Red blood cells
C. Platelets
D. Lymphocytes only
View Answer
Red blood cells contain haemoglobin, which enables them to transport oxygen.
Q9. Which protein in red blood cells carries oxygen?
A. Insulin
B. Haemoglobin
C. Keratin
D. Collagen
View Answer
Haemoglobin is an iron-containing protein that binds oxygen in red blood cells.
Q10. Which organ is the largest internal organ of the human body?
A. Heart
B. Liver
C. Kidney
D. Lung
View Answer
The liver is the largest internal organ and performs many important metabolic and detoxification functions.
Q11. Which organ produces insulin?
A. Liver
B. Pancreas
C. Kidney
D. Stomach
View Answer
The beta cells of the pancreatic islets produce insulin, a hormone that helps regulate blood glucose.
Q12. Which vitamin is mainly produced in the skin when exposed to sunlight?
A. Vitamin A
B. Vitamin B12
C. Vitamin C
D. Vitamin D
View Answer
Exposure to ultraviolet B radiation helps the skin synthesize vitamin D3.
Q13. Which vitamin is important for normal blood clotting?
A. Vitamin A
B. Vitamin C
C. Vitamin K
D. Vitamin D
View Answer
Vitamin K is essential for the synthesis of several proteins involved in blood clotting.
Q14. Which vitamin is also known as ascorbic acid?
A. Vitamin A
B. Vitamin B1
C. Vitamin C
D. Vitamin D
View Answer
Ascorbic acid is the chemical name commonly used for vitamin C.
Q15. Deficiency of vitamin C can cause:
A. Rickets
B. Scurvy
C. Night blindness
D. Beriberi
View Answer
Severe vitamin C deficiency causes scurvy, which can lead to bleeding gums and impaired wound healing.
Q16. Deficiency of vitamin D can cause:
A. Scurvy
B. Rickets
C. Beriberi
D. Pellagra
View Answer
Vitamin D deficiency in children can cause rickets, affecting normal bone mineralization.
Q17. Which vitamin is important for normal vision?
A. Vitamin A
B. Vitamin C
C. Vitamin K
D. Vitamin B12
View Answer
Vitamin A is important for normal vision and the maintenance of healthy epithelial tissues.
Q18. Which disease is associated with severe vitamin B1 deficiency?
A. Scurvy
B. Beriberi
C. Rickets
D. Goitre
View Answer
Severe deficiency of thiamine, or vitamin B1, can cause beriberi.
Q19. Which mineral is essential for the formation of haemoglobin?
A. Calcium
B. Iron
C. Sodium
D. Potassium
View Answer
Iron is an essential component of haemoglobin and is required for normal oxygen transport.
Q20. Which mineral is important for strong bones and teeth?
A. Calcium
B. Sodium
C. Chlorine
D. Iron
View Answer
Calcium is an important mineral for bone and tooth structure and many other physiological functions.
Q21. Where does digestion of carbohydrates begin?
A. Stomach
B. Mouth
C. Small intestine
D. Large intestine
View Answer
Salivary amylase begins the digestion of starch in the mouth.
Q22. Which organ produces bile?
A. Pancreas
B. Liver
C. Stomach
D. Kidney
View Answer
The liver produces bile, which helps in the digestion and absorption of fats.
Q23. Where is bile stored?
A. Pancreas
B. Gallbladder
C. Stomach
D. Spleen
View Answer
The gallbladder stores and concentrates bile produced by the liver.
Q24. Which organ is the main site of nutrient absorption?
A. Stomach
B. Small intestine
C. Large intestine
D. Oesophagus
View Answer
Most digestion and absorption of nutrients takes place in the small intestine.
Q25. Which structures increase the absorptive surface area of the small intestine?
A. Alveoli
B. Villi
C. Nephrons
D. Neurons
View Answer
Villi and their microscopic projections greatly increase the surface area available for nutrient absorption.
Q26. Which enzyme begins the digestion of proteins in the stomach?
A. Amylase
B. Pepsin
C. Lipase only
D. Maltase
View Answer
Pepsin is a stomach enzyme that begins the digestion of proteins into smaller peptides.
Q27. Which organ removes carbon dioxide from the blood?
A. Kidney
B. Lung
C. Liver
D. Stomach
View Answer
The lungs exchange gases, removing carbon dioxide from the blood and adding oxygen.
Q28. What are the tiny air sacs in the lungs called?
A. Nephrons
B. Alveoli
C. Villi
D. Bronchi
View Answer
Alveoli are tiny air sacs where oxygen and carbon dioxide are exchanged between air and blood.
Q29. Which organ controls most activities of the human body?
A. Heart
B. Brain
C. Liver
D. Kidney
View Answer
The brain coordinates many voluntary and involuntary functions and processes information from the body and environment.
Q30. Which part of the brain maintains balance and coordinates movement?
A. Cerebrum
B. Cerebellum
C. Medulla
D. Hypothalamus
View Answer
The cerebellum plays an important role in balance, posture and coordination of movement.
Q31. Which part of the nervous system connects the brain with most of the body?
A. Spinal cord
B. Retina
C. Cerebellum
D. Skull
View Answer
The spinal cord carries nerve signals between the brain and much of the body.
Q32. What is the basic functional unit of the nervous system?
A. Nephron
B. Neuron
C. Alveolus
D. Platelet
View Answer
A neuron is a specialized cell that receives and transmits nerve signals.
Q33. Which hormone helps regulate blood glucose levels by lowering blood sugar?
A. Adrenaline
B. Insulin
C. Thyroxine
D. Growth hormone
View Answer
Insulin promotes glucose uptake and storage, helping lower blood glucose levels.
Q34. Which gland produces thyroxine?
A. Pituitary gland
B. Thyroid gland
C. Adrenal gland
D. Pancreas
View Answer
The thyroid gland produces thyroid hormones, including thyroxine (T4).
Q35. Which mineral is required for the production of thyroid hormones?
A. Iron
B. Iodine
C. Calcium
D. Sodium
View Answer
Iodine is an essential component of thyroid hormones.
Q36. Deficiency of iodine can cause:
A. Goitre
B. Scurvy
C. Rickets
D. Beriberi
View Answer
Iodine deficiency can cause enlargement of the thyroid gland, known as goitre.
Q37. Which gland is often called the master gland?
A. Thyroid
B. Pituitary
C. Adrenal
D. Pancreas
View Answer
The pituitary gland regulates several other endocrine glands and is therefore commonly called the master gland.
Q38. Which hormone is commonly known as the emergency hormone?
A. Insulin
B. Adrenaline
C. Thyroxine
D. Melatonin
View Answer
Adrenaline, or epinephrine, prepares the body for rapid action during stressful or emergency situations.
Q39. Which organelle contains most of the genetic material of a eukaryotic cell?
A. Ribosome
B. Nucleus
C. Golgi apparatus
D. Lysosome
View Answer
The nucleus contains most of the DNA in a eukaryotic cell.
Q40. Which organelle is responsible for protein synthesis?
A. Ribosome
B. Lysosome
C. Vacuole
D. Golgi apparatus
View Answer
Ribosomes are cellular structures where proteins are synthesized.
Q41. Which organelle is known for packaging and modifying proteins?
A. Mitochondrion
B. Golgi apparatus
C. Ribosome
D. Nucleus
View Answer
The Golgi apparatus modifies, sorts and packages proteins and other cellular materials.
Q42. Which organelle contains digestive enzymes that break down cellular waste?
A. Lysosome
B. Ribosome
C. Chloroplast
D. Centriole
View Answer
Lysosomes contain hydrolytic enzymes that help break down cellular waste and worn-out components.
Q43. Which structure controls what enters and leaves the cell?
A. Cell membrane
B. Nucleus
C. Ribosome
D. Chromosome
View Answer
The cell membrane is selectively permeable and regulates movement of substances into and out of the cell.
Q44. Which structure is present in plant cells but generally absent in animal cells?
A. Cell membrane
B. Nucleus
C. Cell wall
D. Mitochondria
View Answer
Plant cells have a rigid cell wall outside the cell membrane, whereas animal cells do not.
Q45. Which organelle is responsible for photosynthesis?
A. Mitochondrion
B. Chloroplast
C. Ribosome
D. Lysosome
View Answer
Chloroplasts contain chlorophyll and are the main sites of photosynthesis in plant cells.
Q46. What is the process by which green plants make food using sunlight?
A. Respiration
B. Photosynthesis
C. Transpiration
D. Digestion
View Answer
Photosynthesis uses light energy to convert carbon dioxide and water into carbohydrates, releasing oxygen as a by-product.
Q47. Which gas do plants mainly absorb from the atmosphere for photosynthesis?
A. Oxygen
B. Carbon dioxide
C. Nitrogen
D. Hydrogen
View Answer
Carbon dioxide provides the carbon used to synthesize carbohydrates during photosynthesis.
Q48. Which tiny openings on leaves help in gas exchange?
A. Villi
B. Stomata
C. Nephrons
D. Alveoli
View Answer
Stomata are small pores on plant surfaces that regulate gas exchange and water loss.
Q49. What is the loss of water vapour from plant leaves called?
A. Respiration
B. Transpiration
C. Photosynthesis
D. Germination
View Answer
Transpiration is the loss of water vapour from plant surfaces, mainly through stomata.
Q50. Which tissue transports water from roots to other parts of a plant?
A. Phloem
B. Xylem
C. Epidermis
D. Cambium only
View Answer
Xylem transports water and dissolved minerals from the roots to the aerial parts of the plant.
Q51. Which tissue transports food in plants?
A. Xylem
B. Phloem
C. Epidermis
D. Cortex
View Answer
Phloem transports sugars and other organic nutrients produced by the plant.
Q52. Which part of a plant absorbs water and minerals from the soil?
A. Flower
B. Roots
C. Fruit
D. Stem only
View Answer
Roots anchor the plant and absorb water and mineral nutrients from the soil.
Q53. Which part of a flower develops into a fruit after fertilization?
A. Ovary
B. Anther
C. Stigma
D. Sepal
View Answer
After fertilization, the ovary generally develops into the fruit while the ovules develop into seeds.
Q54. Which part of a flower produces pollen?
A. Stigma
B. Anther
C. Ovary
D. Sepal
View Answer
The anther is part of the stamen and produces pollen grains.
Q55. What is the transfer of pollen from anther to stigma called?
A. Fertilization
B. Pollination
C. Germination
D. Transpiration
View Answer
Pollination is the transfer of pollen from the anther to the stigma of a flower.
Q56. What is the fusion of male and female gametes called?
A. Pollination
B. Fertilization
C. Germination
D. Budding
View Answer
Fertilization occurs when male and female gametes fuse to form a zygote.
Q57. Which molecule carries genetic information in most living organisms?
A. ATP
B. DNA
C. Glucose
D. Protein
View Answer
DNA stores hereditary genetic information in most organisms.
Q58. What is the full form of DNA?
A. Deoxyribonucleic Acid
B. Dinucleic Acid
C. Deoxyribose Nuclear Acid
D. Double Nucleic Acid
View Answer
DNA stands for deoxyribonucleic acid.
Q59. What is the basic unit of heredity?
A. Cell
B. Gene
C. Tissue
D. Protein
View Answer
A gene is a segment of genetic material that contributes to a hereditary trait or encodes a functional product.
Q60. Which scientist is known as the father of genetics?
A. Charles Darwin
B. Gregor Mendel
C. Louis Pasteur
D. Robert Hooke
View Answer
Gregor Mendel established fundamental principles of inheritance through experiments with pea plants.
Q61. How many pairs of chromosomes are normally present in human body cells?
A. 22
B. 23
C. 24
D. 46
View Answer
Normal human somatic cells contain 23 pairs of chromosomes, or 46 chromosomes in total.
Q62. How many chromosomes are normally present in a human somatic cell?
A. 23
B. 44
C. 46
D. 48
View Answer
Human somatic cells normally contain 46 chromosomes arranged in 23 pairs.
Q63. Which chromosomes determine biological sex in humans?
A. Autosomes
B. Sex chromosomes
C. Ribosomes
D. Mitochondria only
View Answer
The X and Y chromosomes are the human sex chromosomes and play a major role in sex determination.
Q64. Which chromosome combination is typically associated with a human male?
A. XX
B. XY
C. YY
D. XO only
View Answer
In the typical human chromosomal system, males have one X and one Y sex chromosome.
Q65. Which chromosome combination is typically associated with a human female?
A. XX
B. XY
C. YY
D. XO
View Answer
In the typical human chromosomal system, females have two X chromosomes.
Q66. What is the process by which a cell divides into two genetically similar daughter cells?
A. Meiosis
B. Mitosis
C. Fertilization
D. Mutation
View Answer
Mitosis produces daughter cells that generally have the same chromosome number as the parent cell.
Q67. Which type of cell division produces gametes?
A. Mitosis
B. Meiosis
C. Binary fission
D. Budding
View Answer
Meiosis produces haploid reproductive cells and contributes to genetic variation.
Q68. Which blood group is known as the universal red-cell donor in the ABO and Rh system?
A. AB positive
B. A positive
C. O negative
D. B negative
View Answer
O-negative red blood cells lack A, B and RhD antigens and are commonly used as universal red-cell donor blood in emergencies, although proper blood typing is preferred whenever possible.
Q69. Which blood group is commonly called the universal plasma donor?
A. O
B. AB
C. A
D. B
View Answer
AB plasma does not contain anti-A or anti-B antibodies and is therefore considered universal donor plasma in the ABO system.
Q70. Which blood component helps in clotting?
A. Red blood cells
B. Platelets
C. Plasma only
D. White blood cells
View Answer
Platelets play a major role in forming blood clots and stopping bleeding.
Q71. Which chamber of the heart pumps oxygenated blood to the body?
A. Right atrium
B. Right ventricle
C. Left atrium
D. Left ventricle
View Answer
The left ventricle pumps oxygen-rich blood into the aorta for distribution to the body.
Q72. 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
Pulmonary veins carry oxygenated blood from the lungs to the left atrium of the heart.
Q73. Which artery carries blood from the heart to the lungs?
A. Aorta
B. Pulmonary artery
C. Pulmonary vein
D. Vena cava
View Answer
The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs.
Q74. Which is the largest artery in the human body?
A. Pulmonary artery
B. Aorta
C. Carotid artery
D. Femoral artery
View Answer
The aorta is the largest artery and carries oxygenated blood from the left ventricle to the systemic circulation.
Q75. Which organ is primarily responsible for urine formation?
A. Liver
B. Kidney
C. Heart
D. Spleen
View Answer
The kidneys filter blood and form urine as part of the body’s waste-removal and fluid-regulation system.
Q76. What is the functional unit of the kidney?
A. Neuron
B. Nephron
C. Alveolus
D. Villus
View Answer
The nephron is the functional unit of the kidney and is involved in filtration and urine formation.
Q77. Which organ stores urine before it is excreted?
A. Kidney
B. Urinary bladder
C. Ureter
D. Urethra
View Answer
The urinary bladder temporarily stores urine before it leaves the body.
Q78. Which organs are mainly responsible for removing urea from the blood?
A. Lungs
B. Kidneys
C. Heart
D. Stomach
View Answer
The kidneys filter urea and other nitrogenous wastes from the blood and excrete them in urine.
Q79. Which disease is caused by the bacterium Mycobacterium tuberculosis?
A. Malaria
B. Tuberculosis
C. Dengue
D. Cholera
View Answer
Tuberculosis is an infectious disease caused mainly by Mycobacterium tuberculosis.
Q80. Which organism causes malaria?
A. Virus
B. Plasmodium
C. Bacterium
D. Fungus
View Answer
Malaria is caused by parasites of the genus Plasmodium and is transmitted by infected female Anopheles mosquitoes.
Q81. Which mosquito transmits malaria?
A. Male Anopheles
B. Female Anopheles
C. Female Aedes
D. Male Aedes
View Answer
Malaria parasites are transmitted to humans through the bite of infected female Anopheles mosquitoes.
Q82. Dengue is caused by:
A. Bacterium
B. Virus
C. Fungus
D. Protozoan
View Answer
Dengue is caused by dengue viruses and is primarily transmitted by Aedes mosquitoes.
Q83. Which mosquito is a major vector of dengue?
A. Aedes
B. Anopheles
C. Culex only
D. Housefly
View Answer
Aedes aegypti is a major mosquito vector for dengue virus transmission.
Q84. Which disease is caused by the bacterium Vibrio cholerae?
A. Cholera
B. Malaria
C. Influenza
D. Measles
View Answer
Cholera is an intestinal infection caused by Vibrio cholerae and can cause severe watery diarrhoea.
Q85. Which microorganism is used in the production of bread?
A. Yeast
B. Virus
C. Algae
D. Protozoa
View Answer
Yeast ferments sugars and produces carbon dioxide, which helps bread dough rise.
Q86. Which microorganism is commonly used to make curd?
A. Lactobacillus
B. Plasmodium
C. Amoeba
D. Yeast only
View Answer
Lactic acid bacteria such as Lactobacillus help convert milk sugars into lactic acid during curd formation.
Q87. Which scientist developed the first successful smallpox vaccine?
A. Louis Pasteur
B. Edward Jenner
C. Robert Koch
D. Alexander Fleming
View Answer
Edward Jenner demonstrated the protective effect of cowpox vaccination against smallpox in the late 18th century.
Q88. Who discovered penicillin?
A. Alexander Fleming
B. Louis Pasteur
C. Edward Jenner
D. Robert Hooke
View Answer
Alexander Fleming discovered the antibacterial properties of penicillin in 1928.
Q89. Which microorganism is responsible for fermentation of sugar into alcohol?
A. Yeast
B. Virus
C. Algae
D. Amoeba
View Answer
Yeast can ferment sugars anaerobically, producing ethanol and carbon dioxide.
Q90. Which group of organisms can make their own food using photosynthesis?
A. Autotrophs
B. Parasites
C. Carnivores
D. Decomposers only
View Answer
Autotrophs can produce organic food from inorganic substances using energy from light or chemical reactions.
Q91. Which organisms break down dead organic matter?
A. Producers
B. Decomposers
C. Herbivores
D. Primary consumers
View Answer
Fungi and many bacteria act as decomposers by breaking down dead organic matter and recycling nutrients.
Q92. Which organisms are usually the first trophic level in a food chain?
A. Carnivores
B. Producers
C. Decomposers
D. Secondary consumers
View Answer
Producers form the first trophic level because they make organic food and provide energy to higher trophic levels.
Q93. Which gas is essential for aerobic respiration?
A. Nitrogen
B. Oxygen
C. Carbon dioxide
D. Hydrogen
View Answer
Aerobic cellular respiration uses oxygen to help release energy from nutrients.
Q94. What is the process by which cells release energy from food?
A. Photosynthesis
B. Cellular respiration
C. Transpiration
D. Diffusion
View Answer
Cellular respiration breaks down energy-rich molecules such as glucose to produce usable cellular energy, mainly ATP.
Q95. Which molecule is commonly called the energy currency of the cell?
A. DNA
B. ATP
C. RNA
D. Glucose only
View Answer
ATP stores and transfers usable energy for many cellular processes.
Q96. Which part of the eye controls the amount of light entering it?
A. Retina
B. Iris
C. Cornea
D. Optic nerve
View Answer
The iris controls the size of the pupil and therefore regulates the amount of light entering the eye.
Q97. Which part of the eye contains photoreceptor cells?
A. Retina
B. Iris
C. Cornea
D. Lens
View Answer
The retina contains photoreceptor cells called rods and cones that detect light.
Q98. Which part of the ear is mainly responsible for hearing?
A. Cochlea
B. Cerebellum
C. Retina
D. Eardrum only
View Answer
The cochlea contains sensory structures that convert sound vibrations into nerve signals.
Q99. Which is the largest gland in the human body?
A. Thyroid
B. Liver
C. Pancreas
D. Pituitary
View Answer
The liver is the largest gland in the human body and performs numerous metabolic, digestive and detoxification functions.
Q100. Which branch of biology deals with the study of plants?
A. Zoology
B. Botany
C. Ecology
D. Genetics
View Answer
Botany is the branch of biology concerned with the study of plants.
These 100 Biology Practice Questions with answers and explanations cover important topics including human anatomy, cells, plants, genetics, nutrition, diseases, microorganisms, reproduction and ecology. Regular practice of biology questions can help strengthen your basic concepts, improve general science knowledge and support preparation for competitive examinations. Keep practicing more Biology MCQs on PrepTara to improve your accuracy and build a strong foundation in biology.
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