1
The largest organ of the human body is the:
Correct answer: C. Skin
The skin is the largest organ by surface area and weight. The liver is the largest internal organ and the largest gland.
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Human Body and Health MCQs
Solved Everyday Science MCQs on the human body: organs, bones, blood, hormones, vitamins, deficiency diseases and common infections, with explanations.
25 MCQsUpdated 27 October 2026
This set covers the human body and common health facts: the largest organ and smallest bone, the heart and blood groups, vitamins and the diseases caused by their deficiency, and vaccines.
Human body questions are among the most frequent in everyday science papers. Keep a one-page list of "largest, smallest and longest" facts and of vitamin deficiencies; together they cover many likely questions.
- 2
The largest gland in the human body is the:
Correct answer: D. Liver
The liver is the largest gland. It produces bile, stores glycogen and removes toxins from the blood.
easy - 3
How many bones are there in the body of an adult human?
Correct answer: B. 206
An adult has 206 bones. A newborn has around 270–300, and many of them fuse together during growth.
easy - 4
The smallest bone in the human body is the:
Correct answer: D. Stapes
The stapes, one of the three tiny bones of the middle ear, is about 3 mm long. The femur (thigh bone) is the longest.
medium - 5
The longest bone in the human body is the:
Correct answer: D. Femur
The femur, or thigh bone, is the longest and strongest bone in the body.
easy - 6
Insulin is produced by the:
Correct answer: B. Pancreas
Beta cells in the pancreas produce insulin, which lowers blood sugar. A lack of insulin, or resistance to it, causes diabetes.
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How many chambers does the human heart have?
Correct answer: C. 4
The heart has two atria (upper chambers) and two ventricles (lower chambers).
easy - 8
Which blood cells carry oxygen around the body?
Correct answer: C. Red blood cells
Red blood cells contain haemoglobin, an iron-rich protein that binds oxygen in the lungs and releases it in the tissues.
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Which part of the blood helps it to clot?
Correct answer: D. Platelets
Platelets clump together at a wound and, with clotting factors, form a clot that stops bleeding.
easy - 10
A person with which blood group is known as the universal donor for red cells?
Correct answer: A. O negative
O negative red cells have no A, B or Rh(D) antigens, so in emergencies they can be given to patients of any blood group.
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Which blood group is called the universal recipient?
Correct answer: D. AB positive
People with AB positive blood have no anti-A or anti-B antibodies, so they can receive red cells from any ABO and Rh group.
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Scurvy is caused by a deficiency of:
Correct answer: B. Vitamin C
Lack of vitamin C causes scurvy, with bleeding gums and slow wound healing. Citrus fruits are a good source.
easy - 13
Rickets in children is caused by a deficiency of:
Correct answer: A. Vitamin D
Vitamin D is needed to absorb calcium. Without it, bones become soft and weak, causing rickets.
easy - 14
Night blindness is caused by a deficiency of:
Correct answer: C. Vitamin A
Vitamin A is needed to make rhodopsin, the pigment that lets the eyes see in dim light.
easy - 15
Beriberi is caused by a deficiency of:
Correct answer: D. Vitamin B1 (thiamine)
Lack of thiamine (B1) causes beriberi, which affects the nerves and the heart. It was common where people ate mostly polished rice.
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Which vitamin is essential for normal blood clotting?
Correct answer: C. Vitamin K
Vitamin K is needed to make several clotting factors. Newborns are often given a vitamin K injection.
medium - 17
Goitre, a swelling of the thyroid gland, is commonly caused by a lack of:
Correct answer: B. Iodine
The thyroid needs iodine to make its hormones. Iodized salt is used in Pakistan to prevent iodine deficiency.
easy - 18
Malaria is caused by:
Correct answer: A. A Plasmodium parasite
Malaria is caused by Plasmodium parasites and spread by the bite of infected female Anopheles mosquitoes.
medium - 19
Dengue fever is spread by which mosquito?
Correct answer: A. Aedes
The dengue virus is spread mainly by Aedes aegypti mosquitoes, which bite during the day and breed in clean standing water.
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Tuberculosis (TB) is caused by:
Correct answer: B. A bacterium
TB is caused by the bacterium Mycobacterium tuberculosis and spreads through the air when an infected person coughs.
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