Competitive Exam Biology MCQs Set 2 | UPSC, PSC, SSC Practice Questions with Detailed Explanations

Set 2: Biology MCQs for Competitive Exams (Questions 51–100)

51. What is the main function of the nucleus in a cell?

a) Energy production
b) Protein synthesis
c) Genetic control and cell regulation
d) Waste removal

Correct Answer: c) Genetic control and cell regulation
Explanation: The nucleus contains the cell’s genetic material (DNA) and controls all cellular activities by regulating gene expression. It directs protein synthesis and ensures proper cell function.

52. Which process ensures genetic diversity in sexually reproducing organisms?

a) Mitosis
b) Meiosis
c) Binary fission
d) Budding

Correct Answer: b) Meiosis
Explanation: Meiosis introduces genetic diversity through crossing over and independent assortment of chromosomes, resulting in unique gametes each time.

53. What is the function of the Golgi apparatus?

a) Synthesizes proteins
b) Produces ATP
c) Modifies, sorts, and packages proteins for secretion
d) Breaks down cellular waste

Correct Answer: c) Modifies, sorts, and packages proteins for secretion
Explanation: The Golgi apparatus receives proteins from the endoplasmic reticulum, modifies them, and packages them into vesicles for transport within or outside the cell.

54. Which structure is responsible for cell movement in some unicellular organisms?

a) Vacuole
b) Flagellum
c) Nucleus
d) Ribosome

Correct Answer: b) Flagellum
Explanation: Flagella are whip-like structures that enable cell movement in organisms such as sperm cells and some bacteria.

55. What is the primary function of chloroplasts?

a) Cellular respiration
b) Photosynthesis
c) Protein synthesis
d) Lipid synthesis

Correct Answer: b) Photosynthesis
Explanation: Chloroplasts contain chlorophyll and are the sites of photosynthesis, converting light energy into chemical energy (glucose).

56. Which of the following is NOT a function of the liver?

a) Detoxification
b) Bile production
c) Storage of glycogen
d) Production of insulin

Correct Answer: d) Production of insulin
Explanation: The pancreas, not the liver, produces insulin. The liver detoxifies chemicals, produces bile, and stores glycogen.

57. What is the function of the small intestine in digestion?

a) Absorption of water
b) Absorption of most nutrients
c) Storage of food
d) Production of saliva

Correct Answer: b) Absorption of most nutrients
Explanation: The small intestine is adapted for nutrient absorption with its large surface area provided by villi and microvilli.

58. Which blood vessels carry blood away from the heart?

a) Veins
b) Arteries
c) Capillaries
d) Venules

Correct Answer: b) Arteries
Explanation: Arteries carry oxygenated blood away from the heart, except for the pulmonary artery, which carries deoxygenated blood to the lungs.

59. What is the function of white blood cells?

a) Oxygen transport
b) Immune defense
c) Blood clotting
d) Glucose transport

Correct Answer: b) Immune defense
Explanation: White blood cells protect the body against infections and foreign invaders.

60. Which hormone regulates the sleep-wake cycle?

a) Melatonin
b) Insulin
c) Thyroxine
d) Adrenaline

Correct Answer: a) Melatonin
Explanation: Melatonin, produced by the pineal gland, regulates the sleep-wake cycle and circadian rhythms.

61. Which part of the brain is responsible for balance and coordination?

a) Cerebrum
b) Cerebellum
c) Medulla oblongata
d) Hypothalamus

Correct Answer: b) Cerebellum
Explanation: The cerebellum coordinates voluntary movements, maintains posture, and ensures balance.

62. What is the function of the nephron in the kidney?

a) Filtration of blood
b) Production of urine
c) Both a and b
d) Storage of urine

Correct Answer: c) Both a and b
Explanation: The nephron is the functional unit of the kidney, responsible for filtering blood and forming urine.

63. Which is the largest artery in the human body?

a) Aorta
b) Pulmonary artery
c) Coronary artery
d) Carotid artery

Correct Answer: a) Aorta
Explanation: The aorta is the largest artery, carrying oxygenated blood from the heart to the body.

64. What is the main function of the respiratory system?

a) Digestion
b) Circulation
c) Gas exchange
d) Excretion

Correct Answer: c) Gas exchange
Explanation: The respiratory system facilitates the exchange of oxygen and carbon dioxide between the body and the environment.

65. Which of the following is a function of the skin?

a) Protection
b) Sensation
c) Temperature regulation
d) All of the above

Correct Answer: d) All of the above
Explanation: The skin protects against pathogens, senses stimuli, and helps regulate body temperature.

66. What is the primary function of the skeletal system?

a) Movement
b) Support
c) Protection of organs
d) All of the above

Correct Answer: d) All of the above
Explanation: The skeletal system supports the body, protects internal organs, and enables movement with muscles.

67. Which vitamin is essential for blood clotting?

a) Vitamin A
b) Vitamin D
c) Vitamin K
d) Vitamin C

Correct Answer: c) Vitamin K
Explanation: Vitamin K is necessary for the synthesis of clotting factors in the blood.

68. What is the function of the endocrine system?

a) Rapid response to stimuli
b) Slow, long-term regulation via hormones
c) Digestion of food
d) Excretion of waste

Correct Answer: b) Slow, long-term regulation via hormones
Explanation: The endocrine system releases hormones that regulate growth, metabolism, and other long-term processes.

69. Which gland is known as the “master gland”?

a) Thyroid
b) Pituitary
c) Adrenal
d) Pancreas

Correct Answer: b) Pituitary
Explanation: The pituitary gland regulates other endocrine glands and is often called the “master gland.”

70. What is the function of the ribosome?

a) Energy production
b) Protein synthesis
c) Lipid synthesis
d) DNA replication

Correct Answer: b) Protein synthesis
Explanation: Ribosomes are the sites where proteins are synthesized using instructions from mRNA.

71. Which of the following is NOT a part of the human digestive system?

a) Esophagus
b) Trachea
c) Stomach
d) Small intestine

Correct Answer: b) Trachea
Explanation: The trachea is part of the respiratory system, not the digestive system.

72. What is the main function of the large intestine?

a) Absorption of nutrients
b) Absorption of water
c) Digestion of proteins
d) Production of bile

Correct Answer: b) Absorption of water
Explanation: The large intestine absorbs water and electrolytes, forming solid feces from indigestible material.

73. Which of the following is a function of the nervous system?

a) Rapid response to stimuli
b) Long-term regulation
c) Digestion
d) Excretion

Correct Answer: a) Rapid response to stimuli
Explanation: The nervous system enables rapid communication and response to environmental changes.

74. What is the function of the thyroid gland?

a) Regulates calcium levels
b) Regulates metabolism
c) Produces insulin
d) Produces adrenaline

Correct Answer: b) Regulates metabolism
Explanation: The thyroid gland produces hormones that regulate metabolism, growth, and development.

75. Which of the following is a function of the immune system?

a) Oxygen transport
b) Defense against pathogens
c) Blood clotting
d) Digestion

Correct Answer: b) Defense against pathogens
Explanation: The immune system protects the body from infections and diseases.

76. What is the function of the urethra?

a) Transport of urine from the kidney to the bladder
b) Transport of urine from the bladder to the outside
c) Filtration of blood
d) Storage of urine

Correct Answer: b) Transport of urine from the bladder to the outside
Explanation: The urethra carries urine from the bladder to the exterior during urination.

77. Which of the following is NOT a function of the pancreas?

a) Produces digestive enzymes
b) Produces insulin
c) Produces bile
d) Regulates blood sugar

Correct Answer: c) Produces bile
Explanation: The liver produces bile; the pancreas produces digestive enzymes and hormones like insulin.

78. What is the main function of the circulatory system?

a) Transport of nutrients and oxygen
b) Removal of waste products
c) Both a and b
d) Digestion of food

Correct Answer: c) Both a and b
Explanation: The circulatory system transports nutrients, oxygen, and removes waste products.

79. Which of the following is a function of the muscular system?

a) Movement
b) Support
c) Heat production
d) All of the above

Correct Answer: d) All of the above
Explanation: Muscles enable movement, support the body, and generate heat.

80. Which hormone is responsible for regulating blood sugar levels?

a) Insulin
b) Thyroxine
c) Adrenaline
d) Estrogen

Correct Answer: a) Insulin
Explanation: Insulin, produced by the pancreas, lowers blood sugar levels.

81. What is the function of the alveoli in the lungs?

a) Oxygen transport
b) Carbon dioxide transport
c) Gas exchange
d) Blood filtration

Correct Answer: c) Gas exchange
Explanation: Alveoli are tiny air sacs where oxygen and carbon dioxide are exchanged between the lungs and blood.

82. Which of the following is a function of the excretory system?

a) Removal of metabolic wastes
b) Digestion of food
c) Transport of oxygen
d) Production of hormones

Correct Answer: a) Removal of metabolic wastes
Explanation: The excretory system eliminates metabolic wastes such as urea and excess salts.

83. Which of the following is a function of the reproductive system?

a) Production of gametes
b) Production of hormones
c) Both a and b
d) Digestion of food

Correct Answer: c) Both a and b
Explanation: The reproductive system produces gametes and hormones necessary for reproduction.

84. Which of the following is NOT a function of the integumentary system?

a) Protection
b) Sensation
c) Temperature regulation
d) Digestion

Correct Answer: d) Digestion
Explanation: The integumentary system (skin) protects, senses, and regulates temperature but does not digest food.

85. What is the main function of the lymphatic system?

a) Transport of oxygen
b) Immune defense
c) Digestion
d) Excretion

Correct Answer: b) Immune defense
Explanation: The lymphatic system is part of the immune system and helps defend against infections.

86. Which of the following is a function of the endocrine system?

a) Rapid response to stimuli
b) Slow, long-term regulation
c) Digestion
d) Excretion

Correct Answer: b) Slow, long-term regulation
Explanation: The endocrine system uses hormones to regulate long-term processes such as growth and metabolism.

87. What is the function of the cornea in the eye?

a) Focuses light
b) Detects color
c) Produces tears
d) Transmits nerve impulses

Correct Answer: a) Focuses light
Explanation: The cornea is the transparent outer layer of the eye that helps focus light onto the retina.

88. Which of the following is a function of the ear?

a) Hearing
b) Balance
c) Both a and b
d) None of the above

Correct Answer: c) Both a and b
Explanation: The ear detects sound (hearing) and helps maintain balance.

89. What is the function of the spleen?

a) Blood filtration
b) Storage of blood
c) Immune function
d) All of the above

Correct Answer: d) All of the above
Explanation: The spleen filters blood, stores blood, and plays a role in immune defense.

90. Which of the following is a function of the thymus?

a) Production of T-cells
b) Storage of calcium
c) Digestion
d) Excretion

Correct Answer: a) Production of T-cells
Explanation: The thymus is a lymphoid organ where T-cells mature, playing a key role in immunity.

91. What is the function of the adrenal gland?

a) Produces adrenaline
b) Produces cortisol
c) Both a and b
d) None of the above

Correct Answer: c) Both a and b
Explanation: The adrenal gland produces hormones such as adrenaline and cortisol, which regulate stress responses and metabolism.

92. Which of the following is a function of the testis in males?

a) Production of sperm
b) Production of testosterone
c) Both a and b
d) None of the above

Correct Answer: c) Both a and b
Explanation: The testes produce sperm and the hormone testosterone.

93. What is the function of the ovary in females?

a) Production of eggs
b) Production of estrogen and progesterone
c) Both a and b
d) None of the above

Correct Answer: c) Both a and b
Explanation: The ovaries produce eggs (ova) and the hormones estrogen and progesterone.

94. Which of the following is a function of the placenta?

a) Nutrient and gas exchange
b) Waste removal
c) Hormone production
d) All of the above

Correct Answer: d) All of the above
Explanation: The placenta facilitates nutrient and gas exchange, removes wastes, and produces hormones during pregnancy.

95. What is the function of the fallopian tube?

a) Transport of eggs from the ovary to the uterus
b) Production of eggs
c) Production of hormones
d) None of the above

Correct Answer: a) Transport of eggs from the ovary to the uterus
Explanation: The fallopian tubes transport eggs from the ovaries to the uterus.

96. Which of the following is a function of the uterus?

a) Implantation of the embryo
b) Development of the fetus
c) Both a and b
d) None of the above

Correct Answer: c) Both a and b
Explanation: The uterus provides a site for embryo implantation and fetal development.

97. What is the function of the prostate gland in males?

a) Production of sperm
b) Production of seminal fluid
c) Production of testosterone
d) None of the above

Correct Answer: b) Production of seminal fluid
Explanation: The prostate gland produces seminal fluid, which nourishes and transports sperm.

98. Which of the following is a function of the vagina?

a) Receives sperm during intercourse
b) Birth canal
c) Both a and b
d) None of the above

Correct Answer: c) Both a and b
Explanation: The vagina receives sperm during intercourse and serves as the birth canal during childbirth.

99. What is the function of the seminal vesicles?